Entire Report - December 2012


National Overview

NCDC transitioned to the nClimDiv dataset on Thursday, March 13, 2014. This was coincident with the release of the February 2014 monthly monitoring report. For details on this transition, please visit our public FTP site and our U.S. Climate Divisional Database site.

Maps and Graphics

Temperature and Precipitation Ranks
U.S. Percentage Areas
More Information

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Note: GHCN-M Data Notice

An omission in processing a correction algorithm led to some small errors on the Global Historical Climatology Network-Monthly dataset (GHCN-M v3.2.0). This led to small errors in the reported land surface temperatures in the October, November, December and Annual U.S. and global climate reports. On February 14, 2013, NCDC fixed this error in its software, included an additional improvement (described below), and implemented both changes as GHCN-M version 3.2.1. With this update to GHCN-M, the Merged Land and Ocean Surface Temperature dataset also is subsequently revised as MLOST version 3.5.3.

The net result of this new version of GHCN-M reveals very small changes in temperature and ranks. The 2012 U.S. temperature is 0.01°F higher than reported in early January, but still remains approximately 1.0°F warmer than the next warmest year, and approximately 3.25°F warmer than the 20th century average. The U.S. annual time series from version 3.2.1 is almost identical to the series from version 3.2.0 and that the 1895-2012 annual temperature trend remains 0.13°F/decade. The trend for certain calendar months changed more than others (discussed below). For the globe, ranks of individual years changed in some instances by a few positions, but global land temperature trends changed no more than 0.01°C/century for any month since 1880.

NCDC uses two correction processes to remove inhomogeneities associated with factors unrelated to climate such as changes in observer practices, instrumentation, and changes in station location and environment that have occurred through time. The first correction for time of observation changes in the United States was inadvertently disabled during late 2012. That algorithm provides for a physically based correction for observing time changes based on station history information. NCDC also routinely runs a .pairwise correction. algorithm that addresses such issues, but in an indirect manner. It successfully corrected for many of the time of observation issues, which minimized the effect of this processing omission.

The version 3.2.1 release also includes the use of updated data to improve quality control and correction processes of other U.S. stations and neighboring stations in Canada and Mexico.

Compared to analyses released in January 2013, the trend for certain calendar months has changed more than others. This effect is related to the seasonal nature of the reintroduced time-of-observation correction. Trends in U.S. winter temperature are higher while trends in summer temperatures are lower. For the globe, ranks of individual years changed in some instances by a few positions, but global temperature trends changed no more than 0.01°C/century for any month since 1880.

More complete information about this issue is available at this supplemental page.

NCDC will not update the static reports from October through December 2012 and the 2012 U.S and Global annual reports, but will use the current dataset (GHCN-M v. 3.2.1 and MLOST v. 3.5.3) for the January 2013 report and other comparisons to previous months and years.

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National Overview:



December Extreme Weather/Climate Events
  • Climate Highlights — December
  • The average contiguous U.S. temperature for December was 36.4°F, 3.4°F above the 20th century long-term average, and the 10th warmest December on record.
  • Warmer-than-average conditions were present for much of the U.S. east of the Rockies. Twenty states had monthly temperatures that ranked among the ten warmest on record. Near-average conditions were present for the Northern Plains and much of the West. The Pacific Northwest was slightly warmer than average.
  • The nationally-average precipitation for December was 2.74 inches, which was 0.51 inch above average and the 20th wettest December on record.
  • Wetter-than-average conditions were present for the interior West, where Nevada and Utah both had a top ten wet month. The Northeast and parts of the Ohio Valley had a wetter-than-average December. Maine, New York, Ohio, and Pennsylvania also had a top ten wet month. The Southern Plains were drier than average during December.
  • According to the January 1st, 2013 U.S. Drought Monitor report, 61.1 percent of the contiguous U.S. was experiencing moderate-to-exceptional drought, smaller than the 62.7 percent at the end of November. Drought conditions improved in parts of the Southeast, Northwest, and northern California and Nevada. Drought conditions worsened in parts of the Southwest and Southern Plains.
  • Several large snow storms traversed the nation during December causing the monthly average snow cover extent to be above average. According to data from the Rutgers Global Snow Lab, the monthly average snow extent of 1.3 million square miles (3.2 million square km) was 100,800 square miles (261,100 square km) above the 1981-2010 average and the 14th largest monthly snow cover extent in the 47-year period of record.

Alaska Temperature and Precipitation:

  • Alaska had its 18th coolest December since records began in 1918, with a temperature 5.9°F (3.3°C) below the 1971–2000 average.
  • Alaska had its 14th coolest October-December since records began in 1918, with a temperature 3.4°F (1.9°C) below the 1971–2000 average.
  • Alaska had its 11th coolest January-December since records began in 1918, with a temperature 2.3°F (1.3°C) below the 1971–2000 average.
  • Alaska had its 31st driest December since records began in 1918, with an anomaly that was 18.0 percent below the 1971–2000 average.
  • Alaska had its 24th driest October-December since records began in 1918, with an anomaly that was 14.4 percent below the 1971–2000 average.
  • Alaska had its 35th wettest January-December since records began in 1918, with an anomaly that was 9.2 percent above the 1971–2000 average.

For additional details about recent temperatures and precipitation across the U.S., see the Regional Highlights section below and visit the Climate Summary page". For information on local temperature and precipitation records during the month, please visit NCDC's Records page. For details and graphics on weather events across the U.S. and the globe please visit NCDC's Global Hazards page.


Regional Highlights:

These regional summaries were provided by the six Regional Climate Centers and reflect conditions in their respective regions. These six regions differ spatially from the nine climatic regions of the National Climatic Data Center.

  • Northeast Region: (Information provided by the Northeast Regional Climate Center)
  • After a cooler than normal November, December returned to the 2012 trend of above normal temperatures. In fact, with an average temperature of 33.6 degrees F (0.9 degrees C), 4.8 degrees F (2.7 degrees C) above normal, it was the 7th warmest December on record in the Northeast. All states were warmer than normal with all but one placing December 2012 as one their top 15 warmest. Delaware had their warmest December on record averaging 7.0 degrees F (3.9 degrees C) above normal. Departures for the rest of the states ranged from +5.7 degrees F (3.2 degrees C) in Vermont, their 6th warmest, to +3.2 degrees F (1.8 degrees C) in Maine, their 21st warmest. With an average temperature of 50.2 degrees F (10.1 degrees C), 2.7 degrees F (1.5 degrees C) above normal, preliminary data indicates the Northeast region had its warmest year on record. Preliminary data also indicates that eight of twelve of the Northeast states had their warmest year on record while the other four states had one of their top 5 warmest. Departures among the states ranged from +2.0 degrees F (1.1 degrees C) in West Virginia to +3.1 degrees F (1.7 degrees C) in Delaware.
  • On the heels of one of the driest months on record, December turned out to be wetter than normal. With 5.27 inches (133.86 mm) of precipitation (151 percent of normal), it was the 9th wettest December in 118 years in the Northeast. All states reported wetter than normal conditions, with December in nine of twelve states ranked within the 2nd to 23rd wettest. Departures among the states ranged from 103 percent of normal in Connecticut and Maryland to 170 percent of normal in Pennsylvania. Despite a wet end to the year, the Northeast’s annual precipitation total of 42.78 inches (1086.61 mm) was only 96 percent of normal. Delaware, even after being poured on by Hurricane Sandy in October, was the driest of the states. The state was down 11.33 inches (287.78 mm) of precipitation, making it the 6th driest year since 1895. Of the dry states, departures ranged from 75 percent of normal in Delaware to 99 percent of normal in Pennsylvania. Maine was the only state to report above average annual precipitation at 110 percent of normal, their 28th wettest.
  • At the beginning of the month, warm air ahead of an advancing cold front helped several cities set new maximum temperature records. Highs on the 3rd and 4th reached up to 72 degrees F (22.2 degrees C) in the Northeast. A series of storms moved through the region from the 16th to the 19th. Nearly 2 feet (61.0 cm) of snow fell in northern Maine while eastern Pennsylvania had ¼ inch (6.35 mm) hail and parts of Massachusetts had up to ¾ inch (19.05 mm) of ice accumulation. Another storm moved through from the 20th through the 22nd. Two to three inches (50.8 to 76.2 mm) of rain fell in New Jersey, Pennsylvania and Delaware causing flooding and road closures. A Nor’easter on the 26th created difficulties for holiday travelers. The storm dropped over 20 inches (50.8 cm) of snow on parts of upstate New York and Maine. Sections of Interstate 84 and the Taconic State Parkway in New York were closed for several hours due to accidents. Heavy rain, over 3 inches (76.2 mm), and high winds with gusts to 70 mph (31 m/s) affected coastal areas. About 7,000 customers on Long Island lost power. A quick, hard-hitting snowstorm moved through on the 29th bringing another 12 to 20 inches (30.5 to 50.8 cm) to parts of the Northeast. The storm caused a 20-car pileup on Interstate 93 in New Hampshire and a regional jet to skid into a snow bank in Albany, NY.
  • For more information, please go to the Northeast Regional Climate Center Home Page.
  • Midwest Region: (Information provided by the Midwest Regional Climate Center)
  • December temperatures ranged from near normal in northwest Minnesota to as much as 7 degrees F (4 C) above normal in Illinois and Indiana. The first two-thirds of the month were well above normal with the warmest days on the 3rd and 4th recording hundreds of record high temperatures across the Midwest. Cooler temperatures in the final week of the month were not enough to drag the monthly values back down to normal. Six of the nine Midwest states (Illinois, Indiana, Kentucky, Michigan, Missouri, and Ohio) ranked among the ten warmest dating back to 1895 but the region as a whole fell just outside the top ten.
  • Despite the warm temperatures, December had multiple significant snows affect parts of the region. Heavy snows on the 9th and 10th brought up to 13 inches (33 cm) of snow to southern Minnesota. Blizzard conditions extended from Iowa to northern Michigan on the 19th and 20th dropping up to 15 inches (38 cm) of snow in parts of southern Wisconsin. Two storms followed similar paths from southeast Missouri to Lake Erie in the last week of December. The first storm brought blizzard conditions and together they dropped more than 10 inches (25 cm) of snow along the 4-state path. December precipitation totals ranged from less than half normal in northwest Minnesota and western Missouri to more than twice normal in southwest Minnesota and southeast Ohio. Statewide Ohio precipitation of 4.77 inches (121 mm) ranked as the 4th wettest December since 1895.
  • Annual temperatures set records across the Midwest in 2012 based on records that date back to 1895. The region as a whole set a new record of 52.1 degrees F (11.2 C) breaking the 1931 record of 51.9 F (11.1 C). Missouri set a new statewide record of 58.5 F (14.7 C) topping the 1938 record of 57.6 F (14.2 C) while statewide records were tied in Illinois (1921) and Ohio (1998). Each of the six remaining states in the region ranked as the second or third warmest in the last 118 years. Each state had at least one major city, with records dating back prior to 1900, set or tie their annual temperature record: Illinois (Chicago), Indiana (Indianapolis and South Bend), Iowa (Des Moines), Kentucky (Louisville), Michigan (Detroit, Grand Rapids, Lansing, and Muskegon), Minnesota (Minneapolis-St. Paul), Missouri (Columbia and St. Louis), Ohio (Cleveland and Columbus), and Wisconsin (Green Bay, Madison, and Milwaukee).
  • In 2012, the Midwest ranked as the 12th driest calendar year since 1895. Missouri (7th), Illinois (10th), Indiana (11th), and Iowa (11th) all ranked among the driest 10 percent of years and Kentucky and Michigan ranked among the driest 25 percent of years. Drought conditions were widespread in 2012. Drought expanded from 20 percent or less of the region than in the first five months of 2012 to more than 70 percent in July before dropping to around 55 percent by the end of the year. Areas in extreme drought topped 10 percent in July and climbed to more than a third of the region in August before dropping back below 10 percent in November. Drought conditions were most severe in the western third of the Midwest at the end of the year.
  • For details on the weather and climate events of the Midwest, see the weekly summaries in the Midwest Climate Watch page.
  • Southeast Region: (Information provided by the Southeast Regional Climate Center)
  • Monthly average temperatures for December were above normal across the Southeast region. The greatest departures were found across the Carolinas and Virginia, as well as parts of Alabama and Georgia where monthly temperatures were between 5 and 7 degrees F (2.8 to 3.9 degrees C) above normal, while monthly temperatures were between 1 and 3 degrees F (0.5 and 1.6 degrees C) above normal across much of the Florida Peninsula, Puerto Rico, and the U.S. Virgin Islands. The warmest weather occurred during the first half of the month, with temperatures exceeding 70 degrees F (21.1 degrees C) as far north as northern Virginia from the 3rd to the 5th of the month. Temperatures reached 80 degrees F (26.7 degrees C) across eastern sections of Georgia in advance of a cold front from the 10th to the 12th of the month. Overnight temperatures were also warm during this period, with over 150 daily high minimum temperature records tied or broken across the Southeast. The passage of two strong cyclones brought cooler weather to the region during the final two weeks of the month. Subfreezing temperatures were reported as far south as Fort Myers, FL on the 23rd of the month, while maximum temperatures failed to reach 60 degrees F (15.6 degrees C) across parts of central Florida between the 27th and 30th of the month.
  • Precipitation was variable across the Southeast region in December. Monthly totals were between 100 and 200 percent of normal across northern and central parts of Alabama, Georgia, and South Carolina, as well as across portions of North Carolina and the Florida Peninsula. Tuscaloosa, AL recorded 7.61 inches (193.3 mm) of precipitation for the month, which was nearly 3 inches (76.2 mm) above normal, while Atlanta, GA recorded 5.93 inches (150.6 mm) for the month, or more than 2 inches (50.8 mm) above normal. Much of this precipitation was connected with the passage of several strong frontal boundaries, particularly over the Christmas holiday. Newberry, SC, located to the northwest of Columbia, recorded 4.2 inches (106.7 mm) of precipitation on the 25th of the month, which set a monthly record 24-hour rainfall total (period of record: 1893-2012). In contrast, the driest locations were found across South Florida, where monthly rainfall totals were less than 1 inch (25.4 mm), or about 25 percent of normal. Precipitation in December was also variable across Puerto Rico, with above normal rainfall across the southern and western slopes and below normal rainfall across much of the interior and eastern portions of the island. Monthly precipitation was generally below normal across the U.S. Virgin Islands. The storm system that brought heavy rain across southern parts of the region over the Christmas holiday also contributed between 2 and 5 inches (50.8 and 127 mm) of snowfall across northern and western sections of Virginia and the higher elevations of western North Carolina. An additional 3 to 4 inches (76.2 and 101.6 mm) of snow was reported across the mountains of North Carolina and Virginia on the 21st of the month, while trace amounts of snow were reported across northern Alabama in the wake of a departing cyclone on the 29th of the month.
  • There were 118 reports of severe weather across the Southeast in December, including 22 confirmed tornadoes. Two tornadoes touched down near Edgewater, FL in Volusia County on the 10th of the month. The strongest, an EF-1, caused major damage to as many as 45 homes and either snapped or uprooted over 100 trees. Two minor injuries were reported. Three tornadoes were confirmed across central Georgia in Telfair and Wheeler Counties on the 17th of the month, two of which were rated EF-1. Most of the damage was minor. On the 19th of the month, an EF-1 tornado tracked across Mobile, AL during the early morning hours. Numerous trees were snapped or blown down and large sections of roofing were blown off of several homes and businesses. On the 25th of the month, a total of 15 tornadoes were confirmed across central and southern Alabama, making it one of the largest Christmas Day outbreaks on record in the Southeast. Five of these tornadoes were rated EF-2 and resulted in extensive damage to trees, electrical poles, and numerous structures, including collapsed brick walls and cracked cement foundations. Numerous mobile homes were destroyed when the anchors holding them down were ripped from the ground. In some instances, the resulting debris was blown several hundred yards into nearby neighborhoods causing damage to other homes and structures. In one case, two occupants remained inside their home and sustained major injuries. In Mobile, AL, significant damage was reported at Murphy High School where several windows were blown out and some automobiles were flipped onto their sides. In addition, on the 26th of the month, an EF-1 tornado was confirmed near Beaufort, NC in Carteret County.
  • Drought conditions continued to persist across the Southeast in December, as roughly 50 percent of the region was experiencing at least moderate drought (D1 and greater), according to the U.S. Drought Monitor by the end of the month. Areas of severe drought (D2) expanded across northern sections of South Carolina and parts of southwestern North Carolina, while the lack of rainfall across south Florida contributed to the re-emergence of abnormally dry (D0) conditions by the end of December. The dry weather across South Florida forced some citrus farmers to begin irrigating their groves, while warm temperatures aided in the growth of winter vegetables and the harvesting of some early winter crops. Farmers were also beginning to assess whether the subfreezing temperatures experienced towards the end of the month damaged any of their crops. In Georgia, all boat ramps on Lake Lanier were closed indefinitely on the 13th of the month due to low lake levels. However, beneficial rains across North Georgia helped raise the lake level nearly 18 inches (0.5 m) over the last two weeks of the month.
  • For the second straight year, mean annual temperatures in 2012 were exceptionally warm across a large portion of the Southeast region. Several locations recorded their warmest (or tied their warmest) year, including Atlanta, GA, Columbus, GA, Columbia, SC, Norfolk, VA, Richmond, VA, and Washington D.C. Several other locations recorded one of their top 5 warmest years on record, including San Juan, PR, Tampa, FL, Fort Myers, FL, Tallahassee, FL, Montgomery, AL, Birmingham, AL, Huntsville, AL, Charleston, SC, Greenville-Spartanburg, SC, Greensboro, NC, Raleigh-Durham, NC, Cape Hatteras, NC, and Roanoke, VA. In terms of precipitation, it was the fourth driest year on record in Macon, GA and Columbus, GA, with preliminary annual totals of 32.41 and 35.21 inches (823.2 and 894.3 mm), respectively. In contrast, it was the second wettest year on record in Miami, FL with 86.94 inches (2208.3 mm), just 2.4 inches (61 mm) short of the record set in 1959.
  • For more information, please go to the Southeast Regional Climate Center Home Page.
  • High Plains Region: (Information provided by the High Plains Regional Climate Center)
  • December 2012 average temperatures were within 2.0 degrees F (1.1 degrees C) of normal for most of the High Plains Region. Warmer areas included the eastern halves of Nebraska and Kansas, as well as central Wyoming, southern South Dakota, and the panhandle of Nebraska. Monthly average temperatures were generally 2.0-4.0 degrees F (1.1-2.2 degrees C) above normal in those areas, with a few areas ranging from 4.0-8.0 degrees F (2.2-4.4 degrees C) above normal. These temperatures were not record breaking. Cooler areas of the Region included northern North Dakota and south-central Colorado where average temperatures were 2.0-6.0 degrees F (1.1-3.3 degrees C) below normal. Although these temperatures were not low enough to break records, there were some locations that squeezed their way into the top 10 list. Alamosa, Colorado had its 10th coolest December with an average temperature of 11.6 degrees F (-11.3 degrees C), which was 6.3 degrees F (3.5 degrees C) below normal. The record of 5.1 degrees F (-14.9 degrees C) was set in 1991 (period of record 1906-2012). Even though Decem¬ber temperatures were below normal, 2012 ended as one of the warmest years on record in Alamosa. With an aver¬age temperature of 43.2 degrees F (6.2 degrees C), Alamosa had its 7th warmest year on record. The warmest year occurred in 1934 with an average temperature of 44.5 degrees F (6.9 degrees C).
  • There were several storm systems that passed through the High Plains Region this month bringing much needed precipitation. Areas that received above normal precipitation included western portions of Wyoming and Colorado, a swath from eastern Colorado into northern Kansas and up through eastern Nebraska, and also eastern South Dakota. These areas generally received at least 150 percent of normal precipitation and localized areas received upwards of 400 percent of normal precipitation. The most significant storm systems to affect the Region occurred December 8-9, December 19-20, and December 31. The December 8-9 blizzard affected eastern South Dakota bringing localized heavy snow of up to 8.0-14.0 inches (20.0-36.0 cm) and high winds of 40-55 mph (64-89 km/h). This blizzard closed portions of I-29 and I-90. The December 19-20 blizzard brought heavy snow and high winds to much of Nebraska and northern Kansas. This blizzard caused many challenges to travelers as white out conditions closed many roads throughout both states and portions of I-80 in Nebraska. Finally, a New Year’s Eve winter storm blanketed Kansas with snow, the heaviest of which fell in the western part of the state with 6.0-10.0 inches (15-25 cm). Although there was above normal precipitation in many areas of the Region this month, it was not enough to improve the ongoing drought. The highlighted station this month was Grand Island, Nebraska which received 9.5 inches (24 cm) of snow and 1.66 inches (42 mm) of liquid equivalent precipitation. This precipitation amount ranked as the 13th wettest December on record (period of record 1895-2012). What was interesting about December’s precipitation total was that it was the highest precipitation total in one month since May. Although there were many areas which received above normal precipitation, there were also large areas of the Region which did not receive much precipitation this month, including a large area of southeastern Kansas, eastern North Dakota, and eastern Wyoming. These areas received less than 50 percent of normal precipitation. Mean¬while, much of southeastern Kansas received less than 25 percent of normal precipitation.
  • According to the U.S. Drought Monitor, widespread drought conditions continued. Although much of the Region received rain and snow over the past month, this precipitation was only enough to stave off further deterioration of the drought. Overall, about 93 percent of the Region was still in moderate (D1) to exceptional (D4) drought. This was down slightly from the end of last month when 94 percent of the Region was in D1-D4. There were slight improvements in west-central North Dakota where a small section of abnormally dry conditions (D0) were erased and in southwestern Wyoming where a small section of extreme drought (D3) was downgraded to severe drought (D2). Drought conditions worsened slightly in Colorado and other areas of Wyoming. In Wyoming, D3 filled in the central part of the state and a small section of D4 developed in the southwest. In Colorado, D2 expanded in the north, and D3 and D4 conditions expanded slightly in the south. According to the U.S. Seasonal Drought Outlook released January 1st, drought conditions were expected to improve in North Dakota and far northwestern Wyoming. Drought was expected to persist elsewhere through March 2013.
  • For more information, please go to the High Plains Regional Climate Center Home Page.
  • Southern Region: (Information provided by the Southern Regional Climate Center)
  • December was a much warmer month than normal over the entire Southern Region. Most stations averaged approximately 4 to 8 degrees F (2.22 to 4.44 degrees C) above normal. Temperatures in northern Texas, western Oklahoma and southern Louisiana typically averaged between 2 to 4 degrees F (1.11 to 2.22 degrees C) above normal. The highest anomalies were observed in northern Tennessee, where stations averaged between 6 to 8 degrees F (3.33 to 4.44 degrees C) above normal. All six states reported warmer than normal temperatures for the month. The statewide average temperatures for December are as follows: Arkansas reported 46.00 degrees F (7.78 degrees C), Louisiana reported 55.00 degrees F (12.78 degrees C), Mississippi reported 51.40 degrees F (10.78 degrees C), Oklahoma reported 41.80 degrees F (5.44 degrees C), Tennessee reported 45.30 degrees F (7.39 degrees C), and Texas reported 51.00 degrees F (10.56 degrees C). For Tennessee, it was the ninth warmest December on record (1895-2012), while Texas experienced its eleventh warmest on record (1895-2012). The remaining state rankings are as follows: Arkansas with its thirteenth warmest on record (1895-2012), Mississippi with its fourteenth warmest on record (1895-2012), Louisiana with its eighteenth warmest on record (1895-2012), and Oklahoma with its twenty-seventh warmest on record (1895-2012). Two states in the Southern Region also reported 2012 as its warmest year on record (1895-2012). These states are Oklahoma and Texas. Oklahoma's annual temperature average was 62.99 degrees F (17.22 degrees C), while in Texas, the state annual average temperature was 67.48 degrees F (19.71 degrees C). Arkansas reported its second warmest year on record (1895-2012) with an annual temperature average of 63.39 degrees F (17.44 degrees C).
  • December was a drier than normal month for the western half of the Southern Region, while the eastern half experienced a wetter than normal month. The wettest portions of the region were observed in southern Mississippi, where precipitation totals averaged between 150-200 percent of normal. Conversely, much of southern and eastern Texas reported less than half the expected precipitation for the month. This was also the case for much of central Oklahoma. For Oklahoma, it was the thirty-second driest December on record (1895-2012), with a state monthly precipitation total of only 0.93 inches (23.62 mm). Texas experienced its twenty-fourth driest December on record (1895-2012) with a state precipitation total of 1.00 inches (25.40 mm). In contrast, Mississippi averaged 7.05 inches (179.10 mm), which was their twenty-seventh wettest December on record (1895-2012). Conditions were also wet across much of Louisiana. The state averaged 6.32 inches (160.50 mm), and it was their twenty-fifth wettest December (1895-2012). Other state average precipitation totals were as follows: Arkansas with 3.79 inches (96.27 mm), and Tennessee with 5.71 inches (145.00 mm). Ranks for both states fell in the middle two quartiles.
  • Because much of the drought in the Southern Region is confined to Texas, Arkansas and Oklahoma, where precipitation was below average for the month, drought conditions remained relatively unchanged. There is a slightly larger area of extreme and severe drought in central Texas. In addition, the heavy rains in Louisiana helped remove drought conditions in the west central parishes. Some improvement also occurred in western Tennessee.
  • Several tornadoes were reported on Christmas day. The outbreak spanned from southeastern Texas, across southern Louisiana and into southern Mississippi. In Louisiana, one person was reported injured in Rapides Parish. In Mississippi, several tornado injuries were reported. One person was injured in Wilkinson County, four people were injured in Forrest County, while seven were injured in Lawrence County.
  • With state-wide reservoir storage in a declining trend, new water usage restrictions are in place in Austin, Corpus Christi, and several places in north central Texas. Other places are developing new plans for water conservation and storage. The North Texas and Upper Trinity water districts have seen significant declines in reservoir storage in recent months, with the latter planning on adding new lakes to its draw pool to increase total supply storage. Older plans are being further developed, such as the San Angelo plan to develop piping to the Hickory Aquifer, which is expected to see completion by September, 2014. Above average temperatures and low short-term rainfall are also driving concerns over potential wildfires, as evidenced by Bastrop's requesting an additional $7 million for fire response and grassland fires causing strain on some fire response teams (Information provided by the Texas Office of State Climatology).
  • Several frontal passages resulted in strong winds and storms, causing damage in multiple events. Power outages were numerous, with over 60,000 and 70,000 in two separate events in Houston, with an additional 42,000 in Dallas and 4,900 in Austin from the latter event. A system late in the month brought snow and power outages to North Texas and Longview for Christmas, to the tune of 8,000 people without power, and tornadoes in Houston and Beaumont though with much less damage. Minor reports from wind and fog-driven traffic and landscaping damage were common as well in other parts of the state (Information provided by the Texas Office of State Climatology).
  • Dryland crops in central Texas continue to struggle with concerns that winter wheat will not have significant yields. Farmers in the Panhandle are feeling the same concerns, though slightly higher precipitation accumulations are buoying their crops for the time being. Farmers all over the state are concerned about their fiscal future, as the 2008 farm bill allocating $300 billion in farm subsidies expired this year and progress on a new bill has been slow; suggested cuts to the bill between 20 to 30 billion dollars over 10 years is another cause for concern (Information provided by the Texas Office of State Climatology).
  • For more information, please go to the Southern Regional Climate Center Home Page.
  • Western Region: (Information provided by the Western Regional Climate Center)
  • Much of the West saw a continuation of the above normal temperatures that have dominated this calendar year. Positive anomalies were seen throughout the month until the final week, when clear skies, persistent snow cover, and inversions produced cold temperatures that moderated the monthly average to near-normal values at many valley and basin locations. Precipitation was abundant throughout much of the West as an active pattern in the North Pacific brought a series of storms and moderate to heavy precipitation.
  • Following a warm November, the Inland Northwest continued to be anomalously warm in December, with temperatures 3-6 F (1-3 C) above normal. Temperatures for the 2012 calendar year as a whole were above average for this area, especially throughout Montana. Billings saw its warmest year in a 78-year record with an average annual temperature of 51 F (10.5 C), and Missoula recorded its 4th warmest year at 45.3 F (7.4 C). To the south, Riverton, Wyoming saw its second warmest year since records began in 1940 at 48.7 F (9.3 C). In California’s Central Valley, Fresno tied for the 7th warmest December on record, which helped to seal 2012 as the warmest calendar year at an average temperature of 66.7 F (19.3 C). Records in Fresno began in 1948. In the desert Southwest, Tucson, Arizona had only a slightly warmer than average December, but still clinched the title of warmest calendar year in an 82-year record at an average 71.4 F (21.9 C). Phoenix, Arizona recorded its 2nd warmest year with an average annual temperature of 76.7 F (24.8 C). In contrast, central Alaska continued to follow a trend of cooler than normal temperatures that have persisted through the fall. Fairbanks was 13.2 F (7.3 C) cooler than normal this month at an average -17.3 F (-27.4 C), the 14th coldest December in a 63-year record. As Arctic sea ice extent increases after September’s all time low, the positive temperature anomalies present along Alaska’s North Slope throughout summer and fall finally gave way to cooler than normal December averages.
  • A heavy precipitation event that began in the last week of November in the Northwest carried over into the first few days of December. Eight-day precipitation totals for November 28-December 5 exceeded 20 in (508 mm) at Honeydew and Brandy Creek in Northern California. Over 9 in (229 mm) of precipitation was recorded at several other northern California locations, and minor flooding occurred along creeks and rivers. Just before the Christmas holiday, another series of storms brought heavy precipitation to the Pacific Coast and Intermountain West. Storm totals for isolated locations in Northern California exceeded 10 in (254 mm) of rainfall, and locations along the Sierra Nevada crest received over 5 ft (152.4 cm) of snowfall. Another weaker shot of snowfall over the last few days of the month brought Sierra Nevada snowpack to nearly 140% of normal by December 31. In contrast, on the same date last year, the Sierra snowpack stood at 14-28% of normal. These storms also brought 15.8 in (40.1 cm) of snow to Elko, in eastern Nevada, making for the 8th snowiest December there since records began in 1888 with a total snowfall of 22.1 in (56.1cm). The Pacific Northwest received above normal precipitation in December as well, sealing several top-ten wettest year titles for 2012. Seattle-Tacoma Airport in Washington saw its 7th wettest year in a 65-year record with 48.26 in (1225 mm), 130% of normal. In eastern Washington, Spokane recorded its 12th wettest year in a record that began in 1881. In western Oregon, Medford saw its 7th wettest year on record and 146% of normal annual precipitation. Further inland, though wet conditions prevailed for December, 2012 as a whole was a dry. In Billings, Montana, 2012 was driest in a 78-year record at only 7.13 in (181 mm) of precipitation, 52% of normal. Persistent dry conditions led to an extended fire season in Montana that burned over 1 million acres in 2012. Wyoming also saw a dry 2012 with locations throughout the state recording top 10 driest years. In the Pacific, dry conditions continued in Hawaii. Honolulu received only 0.01 in (0.25 mm) rainfall this month, the location’s driest December in a record that began in 1949. Precipitation during the last three months has been below 50% of normal throughout the state with the exception of the west side of Kauai and Hilo on the windward side of the Big Island.
  • December (all month): Fern Lake Fire, Rocky Mountain National Park, Colorado: The Fern Lake fire began on October 9 and was in inaccessible terrain until winds over 70 mph (112 kph) November 30-December 1 doubled the size of the fire and forced evacuations of outlying areas of Estes Park, Colorado. On December 8 and 9, cold temperatures forced firefighters off the fire. The fire is only 88% contained. At year’s end, the number of fires in the United States in 2012 was well below the 10-year average, while the acreage burned ranked third amongst the last 10 years.
  • December 24: Sierra Avalanches: A rain event followed by over 3 ft (91.4 cm) of snow December 22-24 in the Sierra created unstable snow packs. Several avalanches occurred both in the backcountry and at Lake Tahoe area resorts. Two people were killed and two injured in avalanches at ski resorts on the 24th.
  • December 13-14: King Tide Flooding in Coastal California: Astronomical high tides combined with a large swell and moderate precipitation caused minor flooding in low-lying coastal areas of California. Damages were minimal.
  • For more information, please go to the Western Regional Climate Center Home Page.

See NCDC's Monthly Records web-page for weather and climate records for the most recent month. For additional national, regional, and statewide data and graphics from 1895-present, for any period, please visit the Climate at a Glance page.


PLEASE NOTE: All of the temperature and precipitation ranks and values are based on preliminary data. The ranks will change when the final data are processed, but will not be replaced on these pages. Graphics based on final data are provided on the Temperature and Precipitation Maps page and the Climate at a Glance page as they become available.

Global Analysis

Contents of this Section:


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Note: GHCN-M Data Notice

An omission in processing a correction algorithm led to some small errors on the Global Historical Climatology Network-Monthly dataset (GHCN-M v3.2.0). This led to small errors in the reported land surface temperatures in the October, November, December and Annual U.S. and global climate reports. On February 14, 2013, NCDC fixed this error in its software, included an additional improvement (described below), and implemented both changes as GHCN-M version 3.2.1. With this update to GHCN-M, the Merged Land and Ocean Surface Temperature dataset also is subsequently revised as MLOST version 3.5.3.

The net result of this new version of GHCN-M reveals very small changes in temperature and ranks. The 2012 U.S. temperature is 0.01°F higher than reported in early January, but still remains approximately 1.0°F warmer than the next warmest year, and approximately 3.25°F warmer than the 20th century average. The U.S. annual time series from version 3.2.1 is almost identical to the series from version 3.2.0 and that the 1895-2012 annual temperature trend remains 0.13°F/decade. The trend for certain calendar months changed more than others (discussed below). For the globe, ranks of individual years changed in some instances by a few positions, but global land temperature trends changed no more than 0.01°C/century for any month since 1880.

NCDC uses two correction processes to remove inhomogeneities associated with factors unrelated to climate such as changes in observer practices, instrumentation, and changes in station location and environment that have occurred through time. The first correction for time of observation changes in the United States was inadvertently disabled during late 2012. That algorithm provides for a physically based correction for observing time changes based on station history information. NCDC also routinely runs a .pairwise correction. algorithm that addresses such issues, but in an indirect manner. It successfully corrected for many of the time of observation issues, which minimized the effect of this processing omission.

The version 3.2.1 release also includes the use of updated data to improve quality control and correction processes of other U.S. stations and neighboring stations in Canada and Mexico.

Compared to analyses released in January 2013, the trend for certain calendar months has changed more than others. This effect is related to the seasonal nature of the reintroduced time-of-observation correction. Trends in U.S. winter temperature are higher while trends in summer temperatures are lower. For the globe, ranks of individual years changed in some instances by a few positions, but global temperature trends changed no more than 0.01°C/century for any month since 1880.

More complete information about this issue is available at this supplemental page.

NCDC will not update the static reports from October through December 2012 and the 2012 U.S and Global annual reports, but will use the current dataset (GHCN-M v. 3.2.1 and MLOST v. 3.5.3) for the January 2013 report and other comparisons to previous months and years.

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Global Highlights

  • The average combined global land and ocean surface temperature for December 2012 was the 18th warmest December since records began in 1880, at 0.41°C (0.74°F) above the 20th century average of 12.2°C (54.0°F).

  • The globally-averaged land surface temperature for December 2012 was the 49th warmest December on record, at 0.21°C (0.38°F) above average. The globally-averaged ocean surface temperature was the sixth warmest December on record, at 0.47°C (0.85°F) above average.

  • The average combined global land and ocean surface temperature for January–December 2012 was the 10th warmest such period on record, at 0.57°C (1.03°F) above the 20th century average.


==global-temps-errata==

Introduction

Temperature anomalies and percentiles are shown on the gridded maps below. The anomaly map on the left is a product of a merged land surface temperature (Global Historical Climatology Network, GHCN) and sea surface temperature (ERSST.v3b) anomaly analysis developed by Smith et al. (2008). Temperature anomalies for land and ocean are analyzed separately and then merged to form the global analysis. For more information, please visit NCDC's Global Surface Temperature Anomalies page. The December 2012 Global State of the Climate report introduces percentile maps that complement the information provided by the anomaly maps. These new maps on the right provide additional information by placing the temperature anomaly observed for a specific place and time period into historical perspective, showing how the most current month, season or year compares with the past.

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Temperatures

In the atmosphere, 500-millibar height pressure anomalies correlate well with temperatures at the Earth's surface. The average position of the upper-level ridges of high pressure and troughs of low pressure—depicted by positive and negative 500-millibar height anomalies on the December 2012 height and anomaly mapDecember 2012 map—is generally reflected by areas of positive and negative temperature anomalies at the surface, respectively.

December

The December 2012 globally-averaged temperature across land and ocean surfaces was 0.41°C (0.74°F) above the 20th century average of 12.2°C (54.0°F), tying with 1990 and 1994 as the 18th warmest December since records began in 1880 and the coolest December since 2000. This anomaly is significantly lower than the record December warmth of 2003 and 2006, which was 0.75°C (1.35°F) above average.

The global land surface temperature anomaly was 0.21°C (0.38°F) higher than average, the 49th warmest on record for the month of December. It was the coolest December for land surfaces since 1986 and the largest cool temperature anomaly of any month since November 2000. There was sharp contrast between the Northern and Southern Hemisphere land temperatures, with the Southern Hemisphere record warm and the Northern Hemisphere colder than average (-0.07°C / -0.13°F anomaly) for the first time since November 2000, ranking 64th coolest (70th warmest) in the 133-year period of record. For comparison, the average land surface temperature in the Northern Hemisphere for each of the previous eight months (April–November) ranked among the top eight for their respective months. The Northern Hemisphere mid-latitudes (30°N–60°N)—where the majority of the world's human population resides—was 0.70°C (1.26°F) below the 20th century average, the 31st coldest December on record and the coldest December in this latitude belt since 1984.

It was notably colder than average across much of Eurasia, western Canada, and Alaska. As shown by the temperature anomalies map above, December temperatures were more than 5°C (9°F) below the 1981–2010 average across central Asia, parts of western Canada, and eastern Alaska.

Select national information is highlighted below:
  • Through December, Russia experienced its coldest winter to date since 1938, with temperatures as much as 10°–15°C (18°–27°F) below average. Temperatures fell to as low as -50°C (-58°F) in Siberia.

  • According to the China's National Climate Center, from late November through early January, northern and eastern China experienced its coldest temperatures in 28 years for this time of year. The capital city of Beijing observed its lowest average temperature for the period (-6.4°C / 20.4°F) since at least 1951.

  • December was colder than average across all of Sweden. The far north experienced its coldest December since 1986, according to the Swedish Meteorological and Hydrological Institute.

  • The Finish Meteorological Institute reported that December temperatures were well below average, with anomalies ranging from -3° to -5°C (-5.4° to -9°F) across most of the country. The eastern central region experienced temperatures more than 5.5°C (9.9°F) below average.

  • Norway experienced its 11th coolest December since national records began in 1900, at 2.6°C (4.7°F) below average, according to Meteorologisk institutt. The coolest anomalies occurred in the mountains of southern Norway where temperatures were 5°–7°C (9.0°–12.6°F) colder than average.

  • In contrast with November, which had above-average temperatures engulfing the country, most of Hungary was colder than average during December. Temperatures were up to 3°C (5.4°F) below the 1971–2000 average.

  • Average December temperatures across the Republic of Moldova were 2°–4°C (3.6°–7.2°F) below the long-term average. According to Serviciul Hidrometeorlogic de Stat, this is an event that occurs every 5 to 10 years.

  • The U.S. state of Alaska observed its 18th coolest December since records began in 1918. The average monthly temperature was 3.3°C (5.9°F) below the 1971–2000 average.

It was warmer than average across eastern North America, most of South America, southern Asia, Australia, and southern Greenland. Record warmth was observed in southern Brazil, parts of northwestern Australia, and some regions near the equator. The average December temperature was more than 5°C (9°F) above average in part of southeastern Greenland.

  • For the second month in a row, the nationally-averaged monthly maximum temperature across Australia was the fourth highest in the 103-year period of record, with the December temperature 1.23°C (2.21°F) above the 1961–1990 average. Also for the second month in a row, no state or territory reported below-average maximum or minimum average temperatures.

  • The average December temperature across New Zealand was 1.1°C (2.0°F) above the 1971–2000 average, according to the National Institute of Water and Atmospheric Research (NIWA). Many record or near-record monthly temperatures were observed across the North Island, around Nelson, and parts of the eastern South Island.

The December 2012 globally-averaged ocean temperature anomaly of 0.47°C (0.85°F) was the sixth warmest on record for December. For the ninth straight month, ENSO-neutral conditions persisted in the central and eastern equatorial Pacific Ocean, with sea surface temperatures slightly above average in the western Pacific, near average in the central Pacific, and slightly below average in the eastern Pacific. According to NOAA's Climate Prediction Center, neutral conditions are favored to continue through the Northern Hemisphere spring 2013. In other regions, it was notably warmer than average in the north central and northwestern Pacific Ocean, most of the Indian Ocean, the eastern and central Atlantic Ocean, and parts of the mid-latitude southern oceans. Associated with a persistent negative phase of the Pacific Decadal Oscillation, temperatures were cooler than average across the northeastern Pacific Ocean. Images of sea surface temperature conditions are available for all weeks during 2012 from the weekly SST page.

December Anomaly Rank
(out of 133 years)
Records
°C °F Year(s) °C °F
Global
Land +0.21 ± 0.12 +0.38 ± 0.22 Warmest 49th 2003 +1.41 +2.54
Coolest 85th 1929 -1.28 -2.30
Ocean +0.47 ± 0.04 +0.85 ± 0.07 Warmest 6th 1997, 2009 +0.58 +1.04
Coolest 128th 1909 -0.53 -0.95
Land and Ocean +0.41 ± 0.09 +0.74 ± 0.16 Warmest 18th 2003, 2006 +0.75 +1.35
Coolest 116th 1916 -0.57 -1.03
Ties: 1990, 1994
Northern Hemisphere
Land -0.07 ± 0.11 -0.13 ± 0.20 Warmest 70th 1939 +1.78 +3.20
Coolest 64th 1929 -1.60 -2.88
Ocean +0.52 ± 0.06 +0.94 ± 0.11 Warmest 5th 2009 +0.60 +1.08
Coolest 129th 1909 -0.58 -1.04
Land and Ocean +0.30 ± 0.10 +0.54 ± 0.18 Warmest 32nd 2006 +0.99 +1.78
Coolest 102nd 1917 -0.76 -1.37
Southern Hemisphere
Land +0.96 ± 0.12 +1.73 ± 0.22 Warmest 1st 2012 +0.96 +1.73
Coolest 133rd 1909 -0.76 -1.37
Ocean +0.44 ± 0.04 +0.79 ± 0.07 Warmest 11th 1997 +0.62 +1.12
Coolest 123rd 1910 -0.48 -0.86
Land and Ocean +0.52 ± 0.06 +0.94 ± 0.11 Warmest 6th 1997 +0.65 +1.17
Coolest 128th 1909 -0.51 -0.92
Ties: 2004
Year-to-date (January–December)

The January-December 2011 Blended Land and Ocean Surface Temperature Anomalies in degree CelsiusJanuary–December map of temperature anomalies shows that warmer-than-average temperatures occurred across much of the globe during 2012. Global temperatures were influenced by a weak-to-moderate La Niña event at the beginning of the year that transitioned to ENSO-neutral conditions by April, along with global land surface temperatures from April to November that ranked among the top eight for their respective months. Overall, the worldwide combined land and ocean surface temperature was 0.57°C (1.03°F) above the 20th century average, ranking 2012 as the 10th warmest year on record. This temperature anomaly is 0.09°C (0.16°F) less than the record warmth of 2010. Separately, the 2012 average global land surface temperature ranked as the seventh warmest on record and the ocean surface tied with 2001 as the 10th warmest.

Record warmth was observed across much of central North America, central South America, parts of southern and eastern Europe, much of the northeastern coastal Atlantic Ocean, part of the southern Arctic Seas, and sections of the mid-latitude Southern oceans. Also noteworthy, it was much warmer than average across most of North and South America, central and southern Europe, much of northern and coastal Africa, and western, southern, and far northeastern Asia. Temperatures were cooler than average across most of Alaska, part of the northeastern and east central Pacific Ocean, and the Southern Ocean off the southern tip of South America. No record cold regions were observed for the January–December 2012 period. Please refer to the NCDC State of the Climate Annual Global Analysis report for more detailed information.

January–December Anomaly Rank
(out of 133 years)
Records
°C °F Year(s) °C °F
Global
Land +0.90 ± 0.19 +1.62 ± 0.34 Warmest 7th 2007 +1.09 +1.96
Coolest 127th 1884, 1907 -0.59 -1.06
Ocean +0.45 ± 0.03 +0.81 ± 0.05 Warmest 10th 1998, 2003 +0.52 +0.94
Coolest 124th 1909, 1910 -0.45 -0.81
Ties: 2001
Land and Ocean +0.57 ± 0.08 +1.03 ± 0.14 Warmest 10th 2010 +0.66 +1.19
Coolest 124th 1911 -0.44 -0.79
Northern Hemisphere
Land +0.96 ± 0.24 +1.73 ± 0.43 Warmest 8th 2007 +1.22 +2.20
Coolest 126th 1884 -0.70 -1.26
Ocean +0.47 ± 0.04 +0.85 ± 0.07 Warmest 8th 2005 +0.55 +0.99
Coolest 126th 1910 -0.47 -0.85
Land and Ocean +0.65 ± 0.13 +1.17 ± 0.23 Warmest 8th 2010 +0.77 +1.39
Coolest 126th 1912 -0.47 -0.85
Ties: 2004
Southern Hemisphere
Land +0.76 ± 0.11 +1.37 ± 0.20 Warmest 5th 2005 +0.93 +1.67
Coolest 129th 1917 -0.62 -1.12
Ties: 2003
Ocean +0.45 ± 0.03 +0.81 ± 0.05 Warmest 11th 1998 +0.54 +0.97
Coolest 123rd 1911 -0.46 -0.83
Land and Ocean +0.50 ± 0.06 +0.90 ± 0.11 Warmest 9th 1998 +0.59 +1.06
Coolest 125th 1911 -0.46 -0.83
Ties: 1997

The most current data may be accessed via the Global Surface Temperature Anomalies page.

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Images of sea surface temperature conditions are available for all weeks during 2012 from the weekly SST page.


Precipitation

The maps below represent precipitation percent of normal (left) and precipitation percentiles (right) based on the GHCN dataset of land surface stations using a base period of 1961–1990. As is typical, precipitation anomalies during December 2012 varied significantly around the world.

  • Averaged across the country, the Netherlands received 125 mm (4.92 inches) of rainfall during December, 160 percent of normal for the month.

  • December rainfall in Norway was 70 percent of average, marking the 15th driest December on record for the country.

  • According to the UK Met Office, precipitation totals for the UK on average were 150% of the long-term average, making this the wettest December since 1999 and the eighth wettest since records began in 1910.

  • Tropical cyclones rarely hit the southern Philippines; however, Category 5 Super Typhoon Bopha struck southern Mindanao Island in early December, dumping copious rainfall over the region, killing more than 900 residents, and leaving more than 600 missing. This is the same region where Tropical Storm Washi hit just one year earlier, in December 2011, killing more than 1300 people.

Additional details on flooding and drought events around the world can also be found on the December 2012 Global Hazards page.

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References

Peterson, T.C. and R.S. Vose, 1997: An Overview of the Global Historical Climatology Network Database. Bull. Amer. Meteorol. Soc., 78, 2837-2849.

Quayle, R.G., T.C. Peterson, A.N. Basist, and C. S. Godfrey, 1999: An operational near-real-time global temperature index. Geophys. Res. Lett., 26, 333-335.

Smith, T.M. and R.W. Reynolds, 2005: A global merged land air and sea surface temperature reconstruction based on historical observations (1880-1997), J. Clim., 18, 2021-2036.

Smith et al., 2008, Improvements to NOAA's Historical Merged Land-Ocean Surface Temperature Analysis (1880-2006), J. Climate., 21, 2283-2293.

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Global Hazards

Please note: Material provided in this report is chosen subjectively and included at the discretion of the National Climatic Data Center (NCDC). The ability to report on a given event is limited by the amount of information available to NCDC at the time of publication. Inclusion of a particular event does not constitute a greater importance in comparison with an event that has not been incorporated into the discussion. Data included in this report are preliminary unless otherwise stated. Links to supporting information are valid at the time of publication, but they are not maintained or changed after publication.


Updated 29 January 2013

December 2012Wildfires sparked in dry areas of Chile and Australia. read more December 2012Persistent drought worsened in Brazil. read more December 2012Bitter cold led to hypothermia deaths in India and Nepal. read more December 2012Torrential rains inundated parts of Honduras, United Kingdom, and Sri Lanka. read more December 6thTwisters made rare appearances in New Zealand. read more December 2012Storms lashed the Philippines as well as South Pacific islands. read more December 2012Blizzards struck across Eurasia, China, and the U.S. read more

Drought and Wildfires

The advent of the summer season for the Southern Hemisphere brought an increase of wildfires across central and southern Chile. Over 70 acres of meadow, brush, and eucalyptus near Casablanca were ablaze on December 14th, while forest fires burned in other areas of the Valparaiso region. Aerial support boosted the Chilean firefighting efforts to prevent loss of the threatened homes, according to media reports.

Eastern Australian Bushfires on 06 December 2012
Eastern Australian Bushfires
on 06 December 2012
Source: NASA

During December, numerous bushfires sparked in the dry and hot conditions of Queensland as rainfall deficits expanded along the eastern Australian coast. Queensland's monthly maximum temperature anomaly of 1.70°C (3.06°F) was its fifth highest for any month in the 103-year period of record. Overall, the country's average December maximum temperature was the fourth highest on record. More than 50 fires raged in Queensland early in the month. Of four fires were burning in the western region of Darling Down, a massive blaze near Halliford consumed almost 52,000 acres and threatened around a dozen properties. A large fire erupted on North Stradbroke Island, which resulted in the evacuation of residents, and the loss of some structures as well as a recreational vehicle. Heavy smoke was produced by the burning grass and scrub. Large losses of grazing land due to bushfires in northern Queensland posed the threat of starvation for thousands of cattle, according to media reports. In central Victoria, winds drove a large bushfire across more than 4,400 acres, destroying a blue gum plantation and threatening about 20 homes near Seymour. Twenty sheep perished and 100 livestock were injured in the flames. Later in the month, a New South Wales bushfire near Murringo, which burned over 11,000 acres, resulted in the overnight closure of a roadway due to fallen trees and smoke.

Drought conditions worsened in northeastern Brazil where some areas had received almost no rainfall in two years. In the state of Pernambuco, the town reservoir in Sao Jose do Egito ran dry. Annual sugar cane production in the region decreased nearly 30 percent, according to media accounts. In the state of Bahia, officials sought federal resources for close to 20 million residents during December. Farming communities suffered devastating losses of livestock (cattle, goats) and crops (corn, cotton). Reduced water levels resulted in lowered hydro-power generation of electricity as dams contained only 32 percent of their capacity. During 2012, black-outs adversely impacted the region's petrochemical industry, which was forced to import liquefied natural gas for its operations.

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Extreme Temperatures

Bitter cold gripped the South Asian countries of India and Nepal as well as western China in late December. Northern India experienced some of its coldest weather in four decades. Nighttime temperatures hovered near 4.0°C (39.0°F) or lower in the states of Bihar, Uttar Pradesh, and Punjab, accompanied by harsh northwesterly winds. Emergency shelters were established as daily maximum temperatures dropped to below-normal levels by as much as 4.0°C to 10.0°C (7.2°F to 18.0°F). Dense fog disrupted airlines and railway travel on several days. Fatalities among the homeless and the elderly reached 83 persons as of December 31st, which was New Delhi's coldest day of winter through 2012, while colder temperatures continued into January 2013. The death toll tripled by January 10th, according to media reports. Meanwhile, the Red Cross began relief efforts with the distribution of 10,000 blankets.

Thick fog and low temperatures across southern Nepal resulted in at least 13 fatalities from hypothermia by month's end. Distribution of firewood and blankets to residents were the initial assistance as the country's government secured humanitarian aid from UNICEF in early January 2013. Under a five-year program, health care and education support to Nepal's Terai districts will be funded at a value of $144 million U.S. dollars. At least 48 deaths from freezing were reported by Relief Web through January 10th in Nepal.

Snow-covered Chinese Desert on 02 January 2013
Snow-covered Chinese Desert
on 02 January 2013
Source: NASA Earth Observatory

A rare snow fell over the Taklimakan Desert in western China in late December. Heavy snow and strong winds ushered in lower temperatures by up to 8.0°C (14.0°F) across Xinjiang Province. Fog shrouded the cities of Inner Mongolia, lowering visibility to less than 10 meters (33 feet) and temperatures plummeted to near -40.0°C (-40.0°F). Across northern China the extreme cold and snow resulted in increased prices for farm produce and meat. Over 2 million residents were affected by the blizzard conditions, according to media reports.

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Flooding

Central America Hazards Outlook during Nov 29–Dec 5, 2012
Central America Hazards Outlook
during Nov 28–Dec 5, 2012
Source: NOAA Climate Prediction Center

Copious amounts of rain saturated southern Central America during November and December. In northern Honduras, three fatalities occurred due to flooding in the Cortez province in late November. At least seven deaths resulted from flooding in eastern Honduras in early December, according to media reports. In the city of Danli, three people were swept into rising river waters while 14 vehicles and 7 bridges were washed away. Around 150 persons were evacuated and 80 homes were damaged. Torrential rains caused flooding and mudslides in Tegucigalpa, where four persons perished.

Heavy rains, which began in mid-November, continued over the United Kingdom and Ireland during December. Flooding occurred along Ireland's southeastern coastal regions from Cork to Dublin at mid-month. A massive storm battered eastern Scotland, as southeasterly winds, low pressure, and high tides combined to create conditions deemed as the worst in more than 100 years, according to media reports. The 150-year old seawall at North Berwick was swept away during the overnight hours of December 14th–15th and at least 55 residents were evacuated across Aberdeenshire. In northern Scotland, large sections of the harbor walls in Lossiemouth and Balintore. A crew member from an oil vessel in the North Sea perished in towering waves of nearly 6 m (20 ft) and 11 others were rescued. The following week, up to 55 mm (2.2 inches) of additional precipitation fell over the country's north and east. Cancellations of the ferry services in the North Isles resulted and roads were flooded as rivers rose. Scottish rail services were disrupted between Dundee and Aberdeen. Parts of southern England and Wales experienced severe flooding in late December as more than 40 mm (1.6 inches) dropped within 24 hours on December 20th. England's rail services in Devon and Berkshire were suspended. At least 30 properties were flooded when the River Exe overflowed its banks. In Wales, at least four homes were damaged by flooding from heavy rains.

Severe flooding impacted over 93,000 people in northern Sri Lanka during December and the heavy rains continued into January 2013. Flooding and landslides resulted in at least 42 fatalities with injuries to 22 persons, while 9 persons were missing at month's end, according to humanitarian agency reports. More than 24,500 Sri Lankans received shelter in about 150 evacuation centers when nearly 15,000 homes were either destroyed or damaged. Drinking water and non-food items (blankets, sheets, towels, soap) were donated to the districts of Mannar and Anuradhapura by Canada as part of relief assistance valued at $18,700 U.S. dollars. Flooding, which inundated the cultivated paddy land, rendered losses of the rice harvest by as much as 30 percent in Mannar.

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Severe Storms

Three fatalities resulted as the deadliest tornado in more than 60 years hit in New Zealand's North Island on December 6th, according to media reports. Seven people were injured. The storm uprooted trees, damaged buildings, and flooded roads while leaving 1,300 homes without power in the suburbs of Auckland. At least 150 homes were destroyed and about 250 residents were evacuated to emergency shelters. A second tornado touched down several hours later in Rotorua, inflicting injuries on livestock. The country experiences an average of seven tornadoes each year that typically produce minor damage. Three people died in a tornado hitting the city of Hamilton in 1948.

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Tropical Cyclones

Heavy rainfall neared Philippines on 25 December 2012
Heavy rainfall neared Philippines
on 25 December 2012
Source: NASA

In the Western Pacific Ocean, two tropical cyclones took a deadly toll in the Philippines during December. The month began with Super Typhoon Bopha's strike in Mindanao on December 4th, leaving more than 1,000 persons dead and over 800 missing in its wake. At the month's end, Tropical Storm Wukong (a.k.a. Quinta, Dec 24th–28th) became the 17th tropical cyclone to lash the islands during 2012. Over 240,000 people were affected by heavy rains and rough seas as Wukong made multiple landfalls across the Visayas Islands in the Philippines on December 25th–26th. The storm resulted in 20 fatalities with three people injured and four persons missing, according to humanitarian reports. Almost 58,000 people received shelter in 60 evacuation centers as over 5,000 homes were damaged in flash floods and landslides. Close to 6,000 passengers were stranded in port cities when sailing across the region was suspended as waves topped 5 meters (15 feet). The cancellation of 45 airline flights impacted thousands of travelers in Manila as Luzon received some of the storm's heaviest precipitation, according to media reports. Please visit NOAA's Hurricanes and Tropical Storms page for detailed information.

Tropical Cyclone Evan neared Fiji on 16 December 2012
Tropical Cyclone Evan neared Fiji
on 16 December 2012
Source: NASA Earth Observatory

In the South Pacific Ocean,Tropical Cyclone Evan (Dec 9th–19th) formed northeast of Samoa, where the storm made landfall near Apia on December 13th, leaving at least five persons dead and 11 missing, including nine fishermen, according to media accounts. Damages inflicted to the Samoan Islands from the strong, slow-moving storm were considered the worst in two decades. In 1993 the region experienced Cyclone Kina, which killed 23 people, and Cyclone Bebe caused 18 deaths in 1972. High winds and heavy rain resulted in flash floods and power outages, while nearly 800 residents remained in evacuation shelters at the month's end. Humanitarian reports indicated widespread disruption in water and utilities. NASA's Tropical Rainfall Measuring Mission (TRMM) detected an extremely tall thunderstorm reaching 17.0 km (10.5 miles) high at the start of Evan's crossing along Fiji's northern coast on December 16th–17th, where the storm rendered further destruction, but no additional fatalities. High winds and flooding damaged homes while landslides and debris necessitated the closure of roads. Meanwhile, Fiji's air travel was grounded. Clean-up efforts and the distribution of relief items (food, water, blankets, and clothing) ensued.

Tropical Storm Freda neared New Caledonia on 30 December 2012
Tropical Storm Freda neared New
Caledonia on 30 December 2012
Source: NASA Earth Observatory

Later in December, another storm formed in the South Pacific Ocean to the east of the Solomon Islands. Tracking to the southwest, Tropical Cyclone Freda (Dec 26th–Jan 4th) battered Rennell Island and Makira with high winds and heavy thunderstorms. The storm continued south then east, to make landfall in New Caledonia on Jan 2nd resulting in one fatality, according to media reports. Flooding and landslides blocked roads and over 3,200 residents lost power.

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Severe Winter Weather

As heavy snows fell over eastern Europe and Russia during the month, the resulting blizzard conditions paralyzed transportation in much of the region. At least 270 people perished in the bitter December cold, according to media reports. Fatalities exceeded 120 lives in Russia, more than 80 deaths in the Ukraine, nearly 50 deaths in Poland, and numerous deaths in the Balkans with an additional few in the Czech Republic, Germany, and the Netherlands. As much as 40 cm (nearing 16 inches) of snow dropped on December 8th in Zagreb, Croatia, forcing closure of the airport and halting tram and bus services. Strong winds caused delays for ferry and catamaran services with the islands along the Adriatic coast. Hundreds of vehicles were stranded in Serbia's deep snowfall, which topped 20 cm (8 inches). During December 11th–12th, the Ukrainian capital city of Kiev received the largest snowfall in its 130-year period of record with a depth of 45 cm (nearing 18 inches). Over 500 Ukrainians were treated for hypothermia as temperatures plunged to -47.0°C (-52.6°F). In Germany, heavy snow and ice forced a brief closure of the Frankfurt airport (270 flight cancelations) and caused delays for the country's high speed trains. Ice-filled pipes in the Saratov region of Russia left residents without water. In the Tyva region, 3,000 residents were evacuated due to burst heating pipes as temperatures lowered to almost -40.0°C (-40.0°F) in southern Siberia. At month's end, temperatures dropped to about -30°C (-22.0°F) in Moscow and -60.0°C (-76.0°F) in eastern Siberia.

Snowfall spanned central U.S. on 22 December 2012
Snowfall spanned central U.S.
on 22 December 2012
Source: NASA

Parts of North America also experienced blizzard conditions during December. In the U.S., heavy snow and wind created brutal conditions from Colorado to Wisconsin, where snow covered up to 65 percent of the country's lower 48 states in late December. The treacherous storm system resulted in at least 16 fatalities, many related to traffic accidents, according to media accounts. A 120-mile section of Interstate 35 was closed due to a major collision involving 25 vehicles near Des Moines, Iowa. A snowfall in excess of 48 cm (19 inches) occurred in Madison, Wisconsin. Power outages in Arkansas left close to 200,000 homes and businesses without utilities for days. Nearly 30 tornadoes spawned along the Gulf Coast. Across the Northeast, a mix of rain and snow posed travel delays on highways and airlines. Power was lost at over 7,000 homes in Maryland and 800 homes in Vermont. In Montreal, Canada, the daily snowfall of 45 cm (17.7 inches) received on December 27th broke the city's all-time record high daily snowfall previously set in 1971 at 41 cm (16 inches).

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National Snow & Ice

NCDC transitioned to the nClimDiv dataset on Thursday, March 13, 2014. This was coincident with the release of the February 2014 monthly monitoring report. For details on this transition, please visit our public FTP site and our U.S. Climate Divisional Database site.


Overview | Notable Events

Overview:

Despite December being warmer than average for the contiguous U.S., numerous storm systems impacted the Pacific Northwest, Great Plains, and Northeast during the month bringing heavy snowfall. According to NOAA’s National Snow Analysis, at the beginning of December, 13.3 percent of the nation had snow on the ground — the high terrain of the West, along the Canadian border, and the Northeast. Monthly snow cover peaked on December 27th at 65.0 percent of the nation. On December 31st, 61.9 percent of the country was snow covered — much of the West, the Northern and Central Plains, the Mid-South, Ohio Valley, Midwest, and Northeast.

Contiguous US snow cover anomalies
U.S. December Snow Cover Extent Anomalies
Source: Rutgers Global Snow Lab

According to data form the Rutgers Global Snow Lab, above-average December snow cover was observed for much of the West, Great Plains, Ohio Valley, and Mid-Atlantic. Below-average snow was observed for the Southern Rockies and Northeast. As a whole, the contiguous United States experienced above-average December snow cover. The monthly average snow extent of 1.3 million square miles (3.2 million square km) was 100,800 square miles (261,100 square km) above the 1981-2010 average and the 14th largest December monthly snow cover extent in the 47-year period of record.

Summary of Notable Snow Events:

Satellite image of Rockies snow
19 December 2012
Source: NASA

Between December 17th and 22nd, a large winter storm traversed the central U.S. dropping heavy snow along its path and causing blizzard conditions for parts of the Midwest. This storm also ended record streaks for longest period without measurable snow for several locations including Milwaukee, Omaha, and Chicago. The storm caused travel disruptions with over 1,000 flights cancelled when a high volume of people were traveling for the holiday season. The heaviest storm accumulations occurred across the Central and Northern Rockies, where snow totals exceeded 35 inches. Along the southern periphery of the storm system, severe weather was observed across the Southeast.

Snow depth 28 December
Eastern U.S. 28 December Snow Depth
Source: NOAA's NNVL

On the heels of the December 17th – 22nd winter storm, another potent low pressure system brought wintery precipitation to a large portion of the nation on December 25th through 28th. The storm brought snowfall from the Rockies, through the Central and Southern Plains, into the Midwest and Northeast. Snowfall totals over one foot were observed from Arkansas to Maine. The National Weather Service issued blizzard warnings for parts of the Lower Mississippi River and Ohio Valleys where the heavy snowfall was accompanied by strong winds. The storm strengthened as it moved into the Northeast, bringing winds in excess of 60 mph to a large portion of the region.

Synoptic Discussion

Note: This Synoptic Discussion describes recent weather events and climate anomalies in relation to the phenomena that cause the weather. These phenomena include the jet stream, fronts and low pressure systems that bring precipitation, high pressure systems that bring dry weather, and the mechanisms which control these features — such as El Niño, La Niña, and other oceanic and atmospheric drivers (PNA, NAO, AO, and others). The report may contain more technical language than other components of the State of the Climate series.


NCDC transitioned to the nClimDiv dataset on Thursday, March 13, 2014. This was coincident with the release of the February 2014 monthly monitoring report. For details on this transition, please visit our public FTP site and our U.S. Climate Divisional Database site.


Synoptic Discussion

Monthly upper-level circulation pattern and anomalies
Monthly upper-level circulation pattern and anomalies.

With low sun angles in the Northern Hemisphere at the time of the winter solstice (December), solar heating is minimal and cold polar air masses expand southward. The polar jet stream marks the boundary between the polar air masses and the warmer subtropical air masses. Winter storm systems moving in the storm track with the jet stream flow normally lay a blanket of snow in the cold air following in their wake. As winter progresses, the polar jet and polar air masses continue their inexorable expansion to the south — unless other atmospheric drivers act in opposition. This was the case in December 2012. The weather patternweather pattern for the first part of the month consisted of a fairly flat westerly flow with weather patternweak storm systems and a contracted polar jet. The result was unusually warm temperatures across the contiguous United States, a mixed precipitation pattern with large dry areas, and well below-normal snow (on December 6th, snow covered only 6 percent of the country). But the circulation pattern shifted at mid-month to a more vigorous flow with stronger storm systems which brought colder air masses further south (weeks 1, 2, 3, 4), laid down an extensive blanket of snow, and triggered outbreaks of severe weather in the Deep South and Southeast. Snow coverage expanded to 31.9 percent of the country by the 10th, then to 49.3 percent by the 22nd, then again to 65.0 percent by the 27th. Beneficial precipitation helped alleviate drought conditions a bit where it fell (weeks 1, 2, 3, 4), yet many of the drought areas still missed out on the rain and snow. A tornado outbreak associated with a strong storm system on Christmas Day brought the monthly total to 51 preliminary reports of tornadoes, which is about twice the average for December. The number of wildfires for this month was the most for December in the 13-year record, but the amount of acres burned was low so the average fire size was the smallest on record for December.

Monthly precipitation anomalies
Monthly precipitation anomalies.

The movement of the weather systems can be seen in the weekly precipitation anomaly patterns (weeks 1, 2, 3, 4). Beneficial rain and snow helped improve drought conditions over parts of the West, especially the Sierra Nevada and Intermountain Basin (69.3 percent of the West was affected by moderate to exceptional drought at the end of December compared to 72.7 percent at the end of November), and precipitation from frequent frontal systems and low pressure centers chipped away at the drought areas in the Southeast (45.7 percent compared to 46.8 percent) before moving northeast. But with the storm track bringing systems to the West and Southeast, they largely missed much of the Plains, where drought intensified (extreme to exceptional drought expanded in the Southern Plains from 26.8 percent at the end of November to 32.8 percent at the end of December and in the Central to Northern Plains from 57.9 percent to 60.3 percent). Six states (two in the West, three in the Northeast, and Ohio) had the tenth wettest, or wetter, December, while three states (Texas, Oklahoma, and Missouri) ranked in the driest third of the historical record for December. Overall, the precipitation helped reduce the national moderate to exceptional drought footprint from 62.7 percent at the end of November to 61.1 percent at the end of December. According to the Palmer Drought Index, which goes back to the beginning of the 20th century, 51.8 percent of the contiguous U.S. was in moderate to extreme drought at the end of December, a decrease of about 8 percent compared to last month. The 2012 Palmer Drought Index percent area values have been exceeded only by the drought of the 1930s.

Monthly temperature anomalies
Monthly temperature anomalies.

The weekly temperature anomaly maps (weeks 1, 2, 3, 4) show how December began on a very warm note and how warmer-than-normal temperatures dominated until the last week, when weather patterndips (troughs) in the jet stream allowed cold polar air to pour into the middle of the country and parts of the West. Twenty states, from the Mississippi River to the East Coast, had the tenth warmest, or warmer, December, with Delaware ranking warmest on record. On a local basis, six times as many record warm highs and lows occurred than record cold highs and lows. About 1800 daily high temperature records and 2100 record warm daily low temperatures were tied or broken. In comparison, about 300 record low temperatures and 340 record cool daily high temperatures were tied or broken. (These numbers are preliminary and are expected to increase as more data arrive.) The unusual warmth contributed to a national Residential Energy Demand Temperature Index (REDTI) for December 2012 that was sixth lowest for December in the 1895-2012 record.

When averaged together, the mixture of temperature and precipitation extremes gave the U.S. the tenth warmest and 20th wettest December in the 118-year record. Averaging extremes tends to cancel them out. But when extremes are combined cumulatively, like in the U.S. Climate Extremes Index (USCEI), they may tell a different story. Nationally, the large spatial extent of drought conditions (fourth largest PDSI component for December 2012), the frequent heavy precipitation in the West and South (14th largest days with precipitation component), and the large spatial extent of very warm minimum (14th largest) and maximum (22nd largest) temperatures combined to give the U.S. a December USCEI that was 29th largest (out of 103 years). The preponderance of unusual warmth and dryness for much of 2012 has ranked the national USCEI for the year (January-December) as second largest and for the last six months (July-December) as 19th largest (both of these ranks include the warm season tropical cyclone component).

Subtropical highs, and cold fronts and low pressure systems moving in the storm track flow, are influenced by the broadscale atmospheric circulation. Five such large-scale atmospheric circulation drivers were potentially influential during December:

  • El Niño Southern Oscillation (ENSO)
    • Status: Ocean temperatures and atmospheric circulation anomalies indicated that the equatorial Pacific continued in an ENSO-neutral state during December.
    • Teleconnections (influence on weather): To the extent teleconnections are known, while in a neutral state, ENSO normally is not a player in the month's weather. Historical data can be analyzed to show typical temperature and precipitation patterns associated with the ENSO episodes. For an El Niño, the typical October-December temperature anomaly pattern is below-normal temperatures for the southern states and above-normal temperatures for the Northwest to Northern Plains. The typical El Niño October-December precipitation anomaly pattern consists of drier-than-normal conditions for much of the country except patchy wetter-than-normal conditions for the Southwest, Southern Plains, and parts of the Southeast to Mid-Atlantic coast. For a La Niña, the typical October-December temperature anomaly pattern consists of warmer-than-normal conditions from the Great Basin to the Mississippi River, and precipitation anomaly pattern is drier than normal across much of the country from the Southwest to Northeast and Great Lakes to Gulf of Mexico coast, with above-normal precipitation mostly in the Pacific Northwest and Northern California.
    • Observed: The October-December 2012 precipitation pattern matches the La Niña teleconnections for much of the country, and the December 2012 precipitation pattern matches for the Southern Plains and Northwest, but not the East. The October-December 2012 temperature pattern agrees with La Niña, especially for the central part of the country. The December 2012 temperature pattern is not a good match to either phase but agrees more with La Niña than El Niño.
  • The Pacific/North American (PNA) pattern
    • Status: The PNA index was negative for the first two-thirds of December then positive for the last third.
    • Teleconnections (influence on weather): To the extent teleconnections are known, the temperature teleconnection map for this time of year (between October and January on the maps) shows that a negative PNA is correlated with warmer-than-normal temperatures in the Southeast and cooler-than-normal temperatures along the west coast of North America, especially in western Canada and Alaska. The precipitation teleconnections become stronger as the season progresses, and show wetter-than-normal conditions for the Northwest and for much of the country east of the Plains with a negative PNA. The upper-level circulation anomalies associated with a negative PNA are below-normal heights over western North America and above-normal heights over southeastern North America. The opposite conditions are associated with a positive PNA.
    • Observed: December 2012 was wetter than normal in the Northwest and much of the country from the Southeast to Northeast, which agrees with a negative PNA. The December 2012 temperature pattern agrees with a negative PNA in the South and East, but more with a positive PNA in the Northwest. Alaska was colder than normal in December, which is consistent with a negative PNA, and generally drier than normal, but PNA teleconnections are weak for Alaska precipitation. The December 2012 upper-level circulation pattern had strong negative anomalies over western North America, which is consistent with a negative PNA, but the neutral anomalies over southeastern North America and strong positive anomalies over northeastern North America are not consistent with a negative PNA.
  • The Arctic Oscillation (AO) pattern
    • Status: The AO index oscillated from a slightly negative to very negative phase throughout the month.
    • Teleconnections (influence on weather): To the extent teleconnections are known, a negative AO this time of year (October-December) is typically associated with cooler-than-normal temperatures from Montana to Florida and eastward to the Canadian border and the Atlantic Coast, dry conditions from the Southeast to portions of the Central and Southern Plains, and patchy wetter-than-normal conditions in Northern California and New England. The October-December averaged upper-level circulation anomalies for a negative AO are below normal 500-millibar (mb) geopotential heights (which translates to stronger trough or weaker ridge, depending on the circulation) over the eastern half of the U.S. and over the North Pacific Ocean, and above-normal 500-mb heights (which translates to stronger ridge or weaker trough, depending on the circulation) over the Arctic. A positive AO is typically associated with the opposite circulation and temperature patterns.
    • Observed: The December 2012 temperature pattern is not characteristic of any AO phase. While the October-December 2012 temperature pattern has the least positive anomalies in the Northern Plains and Southeast, which hints at a negative AO, the temperature anomalies are mostly positive which do not match what is expected with a negative AO. The October-December 2012 precipitation pattern matches the negative AO teleconnection for Northern California and the Southern and Central Plains to Southeast, but the December 2012 precipitation pattern does not match in the Southeast. The October-December 2012 upper-level circulation had an above-normal pattern over the northwestern Atlantic and Bering Sea area with below-normal geopotential heights over the southeastern U.S. and eastern North Pacific into southwestern Canada. This has some resemblance to a negative AO, but the patterns are significantly shifted and the negative heights are not as strong as in the teleconnection maps.
  • The North Atlantic Oscillation (NAO) pattern
    • Status: The NAO index fluctuated near neutral to negative the first half of December, then near neutral to positive the last half of the month.
    • Teleconnections (influence on weather): To the extent teleconnections are known, a negative NAO during this time of year (January on the teleconnection maps) is typically associated with wetter-than-normal conditions in Northern California and the Great Basin, while a positive NAO is typically drier than normal there. Temperatures this time of year are trending toward cooler than normal for much of the country east of the Rockies for a negative NAO (warmer than normal for a positive NAO). The upper-level circulation anomalies for a negative NAO are below-normal 500-mb geopotential heights over the eastern two-thirds of the contiguous U.S. (above-normal heights for a positive NAO).
    • Observed: The December and October-December 2012 precipitation anomaly patterns match that expected with a negative NAO, while the December temperature pattern matches that expected with a positive NAO. The October-December 2012 temperature pattern and December and October-December 2012 upper-level circulation patterns do not match any NAO teleconnections.
  • The East Pacific-North Pacific (EP-NP) pattern relates sea surface temperature (SST) and upper-level circulation patterns over the eastern and northern Pacific to temperature, precipitation, and circulation anomalies downstream over North America.
Map of three-month temperature anomalies
Map of three-month temperature anomalies.
Map of three-month precipitation anomalies
Map of three-month precipitation anomalies.

Upper-level circulation pattern and anomalies averaged for the last three months
Upper-level circulation pattern and anomalies averaged for the last three months.

Examination of these circulation indices and their teleconnection patterns, and comparison to observed December and October-December 2012 temperature, precipitation, and circulation patterns, suggests that no single atmospheric driver dominated the weather during December, but the weather was influenced in part by several of the drivers. ENSO was neutral and, thus, not a player. The AO was negative, which is normally associated with colder-than-normal temperatures over much of the United States. The dominance of December warmth suggests that the negative PNA and positive NAO countered the negative AO for much of the month. While the EP-NP is not considered by CPC to normally be a leading mode of variability in the winter, if the EP-NP were negative then it, too, would have countered a negative AO. A pattern shift occurred during the last third of the month, with the PNA and NAO changing modes and colder-than-normal air pouring into the country. This month illustrates how competing atmospheric drivers can result in a complex weather pattern and how, when the atmospheric circulation drivers are neutral or in a state of transition, their influence can become difficult to trace and can be overwhelmed by other competing forces, including random fluctuations in the atmosphere.

Tornadoes

NCDC transitioned to the nClimDiv dataset on Thursday, March 13, 2014. This was coincident with the release of the February 2014 monthly monitoring report. For details on this transition, please visit our public FTP site and our U.S. Climate Divisional Database site.


According to data from NOAA's Storm Prediction Center, during December, there were 51 preliminary tornado reports. This is more than the 1991-2010 average of 24 for the month, and once the final tornado count is determined will likely rank among the ten most active Decembers in the 1950-present record. This ends a seven month stretch of below-average tornado activity for the nation. Nearly all of the tornadoes during the month occurred across the Gulf Coast states and the Southeast. There were no reported tornado-related fatalities during December. The last tornado-related fatality in the U.S. occurred on June 24th and December 31st was the 190th consecutive day without a tornado-related fatality. According to analysis by the Storm Prediction Center, the longest consecutive day stretch with no tornado fatalities in the 1950-present official record was 197 days between October 15th, 1986 and February 28th, 1987. Longer periods without tornado fatalities have occurred prior to 1950, but inconsistent observing practices make comparisons to current data difficult.

December 25 2012 Tornadoes
25 December Tornadoes
Source: SPC

On Christmas Day, a strong storm system moved through the center of the country, bringing heavy snow from the Southern Plains into the Northeast and tornadoes and severe weather to the Gulf Coast and Southeast. There were 28 confirmed tornadoes on December 25th from Texas to Alabama and one confirmed tornado in North Carolina on the 26th. The 28 tornadoes on the 25th marked the largest Christmas Day outbreak in the 1950-present record and the fourth most active December tornado day. An EF-3 tornado tracked over 60 miles through southern Mississippi destroying 22 homes and injuring eight people. A second, short-lived EF-3 tornado was confirmed in Pennington, Texas. There were no tornado-related fatalities during the outbreak, although there were four fatalities blamed on other impacts from the severe weather.

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Drought

NCDC transitioned to the nClimDiv dataset on Thursday, March 13, 2014. This was coincident with the release of the February 2014 monthly monitoring report. For details on this transition, please visit our public FTP site and our U.S. Climate Divisional Database site.

Issued 15 January 2013
Contents Of This Report:
Map showing Palmer Z Index

Please note that the values presented in this report are based on preliminary data. They will change when the final data are processed, but will not be replaced on these pages.
National Drought Overview

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Detailed Drought Discussion

Overview

Temperatures were unusually warm during the first week of December, but a circulation change at mid-month brought colder-than-normal air masses to the central regions during the last week (weeks 1, 2, 3, 4). Pacific cold fronts and low pressure systems dumped above-normal precipitation on parts of the country (weeks 1, 2, 3, 4), but they mostly missed the central drought areas. The beneficial rain and snow helped improve drought conditions over parts of the West, especially the Sierra Nevada and Intermountain Basin, and precipitation from the frequent frontal systems and low pressure centers chipped away at the drought areas in the Southeast before the systems moved northeast. But drought intensified in the Plains and expanded in Hawaii. When the temperature and precipitation are averaged across the country for the entire month, December 2012 ranked as the tenth warmest and 20th wettest December in the 118-year record. While not enough to significantly reduce the national drought footprint, the December precipitation did arrest further deterioration on a national scale — the national moderate to exceptional drought footprint decreased from 62.7 percent at the end of November to 61.1 percent at the end of December. According to the Palmer Drought Index, which goes back to the beginning of the 20th century, 51.8 percent of the contiguous U.S. was in moderate to extreme drought at the end of December, a decrease of about 8 percent compared to last month.

The U.S. Drought Monitor drought map valid January 1, 2013
The U.S. Drought Monitor drought map valid January 1, 2013.

By the end of the month, the core drought areas in the U.S. included:


Palmer Drought Index

The Palmer drought indices measure the balance between moisture demand (evapotranspiration driven by temperature) and moisture supply (precipitation). The Palmer Z Index depicts moisture conditions for the current month, while the Palmer Hydrological Drought Index (PHDI) and Palmer Drought Severity Index (PDSI) depict the current month's cumulative moisture conditions integrated over the last several months.

Palmer Z Index map Palmer Hydrological Drought Index map

Used together, the Palmer Z Index and PHDI maps show that the December short-term moisture conditions improved long-term drought in the West, Northern Plains, Upper Midwest, and Southeast, but December short-term conditions deteriorated long-term drought in the Central and Southern Plains (December PHDI compared to November PHDI). The combination resulted in a decrease in the total percent area under drought. The Northeast and Northwest also received above-normal precipitation in December, but they were already mostly drought-free.


Standardized Precipitation Index

The Standardized Precipitation Index (SPI) measures moisture supply. The SPI maps here show the spatial extent of anomalously wet and dry areas at time scales ranging from 1 month to 24 months.

1-month Standardized Precipitation Index 2-month Standardized Precipitation Index 3-month Standardized Precipitation Index

The 1-month SPI map shows that the moisture deficiencies in December were moderately dry or worse for only parts of the Central and Southern Plains and Central Rockies. December was moderately to extremely moist for parts of the West and Upper Midwest, a little of the Deep South, and much of the Ohio Valley to Northeast. Much of the West (especially the northern sections) and Northern Plains was wet at 2 and 3 months, parts of the West were wet at 6 and 9 months, and the Northwest was wet at all time scales from 2 to 24 months. Dryness appears in pockets of the Northeast at 2 to 12 months, but the general pattern is wet conditions at most time scales. Dryness in the Mid-Atlantic is obvious at 2 to 12 months, while recent rainfall has helped the Southeast at 1 to 2 months but dryness becomes more pervasive at the longer time scales starting at 3 and going to 24 months. The Central Rockies were dry from 2 to 24 months, with the most extreme dryness at 9 and 12 months. The Southwest was also dry from 2 to 24 months, but the most extreme dryness is evident at the longer time scales. The 2012 drought of the Great Plains and Midwest shows up at time scales as short as 2 months, but is most evident at 6 to 12 months.


6-month Standardized Precipitation Index 12-month Standardized Precipitation Index 24-month Standardized Precipitation Index


Agricultural and Hydrological Indices and Impacts

University of Washington VIC Model soil moisture percentile
University of Washington VIC Model soil moisture percentile
USGS monthly streamflow percentiles
USGS monthly streamflow percentiles

Drought conditions were reflected in numerous agricultural, hydrological, and other meteorological indicators, both observed and modeled.

Agricultural:

According to the U.S. Department of Agriculture (USDA), as of January 1, 62 percent of winter wheat, 64 percent of hay, and 73 percent of cattle were in drought. For the 26th consecutive week (July 10, 2012 - January 1, 2013), drought encompassed more than two-thirds of the domestic cattle inventory and at least 60 percent of the domestic hay acreage.

Map showing NOAA/NCEP NLDAS modeled monthly soil moisture percentiles (top 1 meter)
Map showing NOAA/NCEP NLDAS modeled monthly soil moisture percentiles (top 1 meter).

Hydrological:

Map showing NOAA/NCEP NLDAS modeled monthly streamflow anomaly
Map showing NOAA/NCEP NLDAS modeled monthly streamflow anomaly.

Meteorological:

Map showing number of days with precipitation
Map showing number of days with precipitation.


Regional Discussion

Hawaii: December 2012 was another very dry month for the Hawaiian Islands, especially for the leeward stations. Honolulu was record dry for December with only 0.01 inch of rainfall. The pattern of below-normal rainfall was evident at most time periods (especially the last 2, 3, 6, and 36 months, but also the last 9, 12, and 24 months), and streamflow was below normal, especially on Oahu. Moderate to extreme drought affected almost two-thirds of the state, about ten percent more than last month.

Alaska: Most of the stations in Alaska were drier and cooler than normal during December 2012, giving the state its 31st driest and 18th coolest December in the 1918-2012 record. The dryness is widespread at 2, 3, and 6 months, especially from the central to southeastern stations. But the pattern is mixed at longer time scales (9, 12, 24, and 36 months). An area of abnormal dryness covers the northern and eastern two-thirds of the state on the USDM map, and a spot of moderate drought was added to the Koyukuk Basin where the water content of the snowpack was extremely low (21 percent of average).

Puerto Rico: Eastern Puerto Rico was drier than normal during December. The last 2 to 3 months have been very dry in the southeastern areas, with this dryness evident at longer time scales (6 to 12 months). An area of D0 (abnormally dry) was added to the USDM map where December streamflows were consistently low.

CONUS State Ranks:

Current month state precipitation ranks Current 3-month state precipitation ranks

On a statewide basis, December 2012 ranked in the driest third of the historical record for three states — Texas, Oklahoma, and Missouri. The area of dryness was still centered in the Southern Plains at three months, with Texas (third driest) and Oklahoma (ninth driest) having the tenth driest, or drier, October-December and eleven other states ranking in the direst third of the historical record.

6-month state precipitation ranks Nebraska statewide precipitation, July-December, 1895-2012

At the six-month time scale the Rockies to Great Plains and Upper Midwest were the epicenter of dryness, with Nebraska having the driest July-December in the 1895-2012 record and seven other states ranking in the top ten driest category. It was so dry in Nebraska that the state was driest for all seasons from August-December back to January-December.

12-month state precipitation ranks Wyoming statewide precipitation, January-December, 1895-2012

The spatial pattern of dryness for the year was similar to that for the last 6 months, except the dryness stretched further into the Ohio Valley and from the Southeast to the Mid-Atlantic states. Nebraska and Wyoming had the driest year on record and eight other states ranked in the top ten driest category, including Georgia and Delaware. It was so dry in Wyoming that the state was driest for all seasons from April-December back to January-December.

Western U.S.


Percent area of the Western U.S. in moderate to extreme drought, January 1900 to present, based on the Palmer Drought Index
Percent area of the Western U.S. in moderate to extreme drought, January 1900 to present, based on the Palmer Drought Index.

Beneficial rain and snow fell across much of the West during December. Above-normal temperatures were not as widespread this month, allowing the buildup of a substantial snow pack in places. Water year-to-date (October-present) precipitation was above-normal in the northwestern regions and below-normal in the southeastern areas of the West — especially in the Central and Southern Rockies — as seen in both low elevation and high elevation (SNOTEL) stations. Snow pack snow water content (station percentiles, basin percent of normal) was below-normal in the Central to Southern Rockies, where precipitation was lacking, and also below-normal across parts of the Great Basin to Pacific Northwest, where temperatures have been above normal. Reservoir storage was above average, statewide, in Montana and Washington, where abundant precipitation has fallen so far this water year, near average in Wyoming and Utah, which have received beneficial precipitation recently, but below average in the southwestern states as well as Idaho and Oregon in the northwest. According to the USDM, 69.3 percent of the West was experiencing moderate to exceptional drought at the end of December, a three percent decrease compared to November. The Palmer Drought Index percent area statistic was about 48 percent, a decrease of 18 percent compared to last month.


NOAA Regional Climate Centers:


A more detailed drought discussion, provided by the NOAA Regional Climate Centers and others, can be found below.

SoutheastSouthMidwestNortheastHigh Plains
WestUpper Colorado River BasinPacific Islands

As described by the High Plains Regional Climate Center, several storm systems passed through the High Plains region this month bringing much needed precipitation. Although there were many areas which received above normal precipitation, there were also large areas of the region which did not receive much precipitation this month, including a large area of southeastern Kansas, eastern North Dakota, and eastern Wyoming. These areas received less than 50 percent of normal precipitation. Meanwhile, much of southeastern Kansas received less than 25 percent of normal precipitation. For the areas that received rain and snow this month, the precipitation was only enough to stave off further deterioration of the drought. Overall, about 93 percent of the region was still in moderate (D1) to exceptional (D4) drought. This was down slightly from the end of last month when 94 percent of the region was in D1-D4. There were slight improvements in west-central North Dakota where a small section of abnormally dry conditions (D0) were erased and in southwestern Wyoming where a small section of extreme drought (D3) was downgraded to severe drought (D2). Drought conditions worsened slightly in Colorado and other areas of Wyoming. In Wyoming, D3 filled in the central part of the state and a small section of D4 developed in the southwest. In Colorado, D2 expanded in the north, and D3 and D4 conditions expanded slightly in the south.

As explained by the Southern Regional Climate Center, December was a much warmer month than normal over the entire region, drier than normal for the western half of the region, and wetter than normal in the eastern half. Because much of the drought in the Southern region is confined to Texas, Arkansas and Oklahoma, where precipitation was below average for the month, drought conditions remained relatively unchanged. There is a slightly larger area of extreme and severe drought in central Texas. In addition, the heavy rains in Louisiana helped remove drought conditions in the west central parishes. Some improvement also occurred in western Tennessee. With state-wide reservoir storage in a declining trend, new water usage restrictions are in place in Austin, Corpus Christi, and several places in north central Texas. Other places are developing new plans for water conservation and storage. The North Texas and Upper Trinity water districts have seen significant declines in reservoir storage in recent months, with the latter planning on adding new lakes to its draw pool to increase total supply storage. Older plans are being further developed, such as the San Angelo plan to develop piping to the Hickory Aquifer, which is expected to see completion by September, 2014. Above average temperatures and low short-term rainfall are also driving concerns over potential wildfires, as evidenced by Bastrop's requesting an additional $7 million for fire response and grassland fires causing strain on some fire response teams (Information provided by the Texas Office of State Climatology). Dryland crops in central Texas continue to struggle with concerns that winter wheat will not have significant yields. Farmers in the Panhandle are feeling the same concerns, though slightly higher precipitation accumulations are buoying their crops for the time being. Farmers all over the state are concerned about their fiscal future, as the 2008 farm bill allocating $300 billion in farm subsidies expired this year and progress on a new bill has been slow; suggested cuts to the bill between 20 to 30 billion dollars over 10 years is another cause for concern (Information provided by the Texas Office of State Climatology).

As summarized by the Midwest Regional Climate Center, December temperatures ranged from near normal in northwest Minnesota to as much as 7 degrees F (4 C) above normal in Illinois and Indiana. The first two-thirds of the month were well above normal with the warmest days on the 3rd and 4th recording hundreds of record high temperatures across the Midwest. Cooler temperatures in the final week of the month were not enough to drag the monthly values back down to normal. Despite the warm temperatures, December had multiple significant snows affect parts of the region. December precipitation totals ranged from less than half normal in northwest Minnesota and western Missouri to more than twice normal in southwest Minnesota and southeast Ohio.

In the Midwest, 2012 ranked as the 12th driest calendar year since 1895. Missouri (7th), Illinois (10th), Indiana (11th), and Iowa (11th) all ranked among the driest 10 percent of years and Kentucky and Michigan ranked among the driest 25 percent of years. Drought conditions were widespread in 2012. Drought expanded from 20 percent or less of the region than in the first five months of 2012 to more than 70 percent in July before dropping to around 55 percent by the end of the year. Areas in extreme drought topped 10 percent in July and climbed to more than a third of the region in August before dropping back below 10 percent in November. Drought conditions were most severe in the western third of the Midwest at the end of the year.

As noted by the Southeast Regional Climate Center, monthly average temperatures for December were above normal across the Southeast region, including Puerto Rico and the U.S. Virgin Islands. Precipitation was variable across the region. The driest locations were found across South Florida, where monthly rainfall totals were less than 1 inch (25.4 mm), or about 25 percent of normal. Precipitation in December was also variable across Puerto Rico, with above normal rainfall across the southern and western slopes and below normal rainfall across much of the interior and eastern portions of the island. Monthly precipitation was generally below normal across the U.S. Virgin Islands.

Drought conditions continued to persist across the Southeast in December, as roughly 50 percent of the region was experiencing at least moderate drought (D1 and greater), according to the USDM by the end of the month. Areas of severe drought (D2) expanded across northern sections of South Carolina and parts of southwestern North Carolina, while the lack of rainfall across south Florida contributed to the re-emergence of abnormally dry (D0) conditions by the end of December. The dry weather across South Florida forced some citrus farmers to begin irrigating their groves, while warm temperatures aided in the growth of winter vegetables and the harvesting of some early winter crops. Farmers were also beginning to assess whether the subfreezing temperatures experienced towards the end of the month damaged any of their crops. In Georgia, all boat ramps on Lake Lanier were closed indefinitely on the 13th of the month due to low lake levels. However, beneficial rains across North Georgia helped raise the lake level nearly 18 inches (0.5 m) over the last two weeks of the month.

As explained by the Northeast Regional Climate Center, after a cooler than normal November, December returned to the 2012 trend of above normal temperatures. On the heels of one of the driest months on record, December turned out to be wetter than normal. With 5.27 inches (133.86 mm) of precipitation (151 percent of normal), it was the 9th wettest December in 118 years in the Northeast. All states reported wetter than normal conditions. Despite a wet end to the year, the Northeast's annual precipitation total of 42.78 inches (1086.61 mm) was only 96 percent of normal. Delaware, even after being poured on by Hurricane Sandy in October, was the driest of the states. The state was down 11.33 inches (287.78 mm) of precipitation, making it the 6th driest year since 1895.

As summarized by the Western Regional Climate Center, much of the West saw a continuation of the above normal temperatures that have dominated this calendar year. Positive anomalies were seen throughout the month until the final week, when clear skies, persistent snow cover, and inversions produced cold temperatures that moderated the monthly average to near-normal values at many valley and basin locations. Precipitation was abundant throughout much of the West as an active pattern in the North Pacific brought a series of storms and moderate to heavy precipitation. In contrast, central Alaska continued to follow a trend of cooler than normal temperatures that have persisted through the fall. As Arctic sea ice extent increases after September's all time low, the positive temperature anomalies present along Alaska's North Slope throughout summer and fall finally gave way to cooler than normal December averages. A series of winter storms brought Sierra Nevada snowpack to nearly 140 percent of normal by December 31. In contrast, on the same date last year, the Sierra snowpack stood at 14 to 28 percent of normal. The Pacific Northwest received above normal precipitation in December as well, sealing several top-ten wettest year titles for 2012. Further inland, though wet conditions prevailed for December, 2012 as a whole was a dry. In Billings, Montana, 2012 was driest in a 78-year record at only 7.13 in (181 mm) of precipitation, 52 percent of normal. Persistent dry conditions led to an extended fire season in Montana that burned over 1 million acres in 2012. Wyoming also saw a dry 2012 with locations throughout the state recording top 10 driest years. In the Pacific, dry conditions continued in Hawaii. Honolulu received only 0.01 in (0.25 mm) rainfall this month, the location's driest December in a record that began in 1949. Precipitation during the last three months has been below 50 perent of normal throughout the state with the exception of the west side of Kauai and Hilo on the windward side of the Big Island.

Upper Colorado River Basin: As reported by the Colorado Climate Center, the January 1st NIDIS (National Integrated Drought Information System) assessment for the Upper Colorado River Basin (UCRB) indicated that, for the month of December, the UCRB has received around a half inch to inch of precipitation in the lower elevations and more in the higher elevations. Areas of the northern and central Colorado mountains, the higher elevations in western Wyoming, and along the Wasatch and Uintah ranges in Utah have received between 2 and 6 inches of precipitation for the month. This is about average for this time of year, but has been a welcome relief for areas that were much drier than average during October and November. East of the basin, the rest of Colorado received between 0.25 and 1.00 inches for the month. Accumulated snowpack is currently less than normal on the east side of the UCRB and near to above normal on the west side of the basin. Sub-basins in western CO are all between 70 percent and 85 percent of normal snowpack. Northeast UT and southwest WY basins are around 100 percent of normal snowpack (with a few sub-basins in UT greater than 110 percent of normal). Snowpack in western CO has seen large improvements since the beginning of December, with all sub-basins improving by 30 percent to 40 percent. The Colorado headwaters region is one of the sub-basins to show large improvement over the past month. Early in the water year, very little snow was accumulating in that region, leading to a deficit of over an inch by the beginning of December. The month of December has seen large snow accumulations, so that the Colorado headwaters region is no longer showing a deficit and is very near average now for this time of year. For the month of December, most of the major reservoirs in the UCRB saw minor volume decreases, though Blue Mesa Reservoir saw a very slight increase since the beginning of the month. Volume decreases are normal for this time of year, and most of the reservoirs decreased less than what is normal. Flaming Gorge levels are near December averages while the rest of the reservoirs are between 60 percent and 80 percent of average.

Pacific Islands: According to reports from National Weather Service offices, the Pacific ENSO Applications Climate Center (PEAC), and partners, conditions varied across the Pacific Islands.

As noted by the National Weather Service office in Honolulu, wet trade wind conditions brought ample amounts of rainfall to the east-facing slopes. Periods of strong trade winds helped blow rainfall into some of the leeward areas of the smaller islands. However, leeward areas of Maui County and the Big Island remained very dry. This persistent leeward dryness produced an expansion of extreme drought, or D3 category conditions in the USDM map, in portions of Maui County. On the island of Maui, the D3 area over Kihei spread northward into lower Kula and eastward into Ulupalakua and Kaupo. On Molokai, the existing extreme drought area over western Molokai spread eastward into the central portion of the island. Extreme drought remains unchanged on the Big Island and continues to cover most of the south Kohala district, the Pohakuloa region of the Hamakua district, the north-facing slopes of Hualalai in the north Kona district, and the lower elevations of southwest Kau. On Kauai, the area of severe drought, or D2 category conditions on the USDM map, decreased over the past month and is confined to the lower elevations of south Kauai from Poipu to Hanapepe. Severe drought also continued over west Oahu from Nanakuli to Makaha, the lower leeward slopes of the west Maui mountains, and in the Humuula Saddle region of the Big Island.

Some drought impacts impacts in Hawaii include the following:

KAUAI.
RAINFALL OVER THE PAST MONTH HAS HELPED IMPROVE PASTURE CONDITIONS
BUT FURTHER IMPROVEMENTS ARE NEEDED FOR FULL RECOVERY.  RANCHERS
WILL NOT YET RESTOCK PASTURES UNTIL PASTURES IMPROVE FURTHER.

OAHU.
PASTURES AND GENERAL VEGETATION REMAIN IN POOR CONDITION
OVER THE LEEWARD WAIANAE RANGE AS MOST OF THE RAINFALL ACTIVITY OVER
THE PAST MONTH HAS OCCURRED MOSTLY OVER THE KOOLAU RANGE.  WEST OAHU
RANCHERS DESTOCKED PASTURES SEVERAL MONTHS AGO DUE TO POOR GRAZING
CONDITIONS.

MOLOKAI.
VERY POOR PASTURE CONDITIONS IN WEST MOLOKAI HAVE SPREAD EASTWARD
INTO THE CENTRAL PORTION OF THE ISLAND.  RANCHERS HAVE BEEN CULLING
HERDS AT A GREATER THAN NORMAL RATE.

THE WATER LEVEL IN THE KUALAPUU RESERVOIR INCREASED A FEW FEET OVER
THE PAST MONTH BUT REMAINS VERY LOW.  THUS...THE STATE OF HAWAII
DEPARTMENT OF AGRICULTURE HAS CONTINUED A MANDATORY 30 PERCENT
REDUCTION IN IRRIGATION WATER CONSUMPTION.

LANAI.
NO SIGNIFICANT CHANGES SINCE THE DECEMBER 6 UPDATE.  EARLIER REPORTS
INDICATED THAT THE MIDDLE AND LOWER ELEVATIONS OF THE
ISLAND...ESPECIALLY ALONG THE NORTH-...EAST- AND SOUTH-FACING
SLOPES...WERE VERY DRY AND PLANTS AND ANIMALS IN THESE AREAS HAVE
BEEN STRUGGLING TO SURVIVE.

MAUI.
LEEWARD MAUI WAS VERY DRY OVER THE PAST MONTH CAUSING POOR PASTURE
CONDITIONS TO SPREAD INTO THE LOWER KULA...ULUPALAKUA AND KAUPO
AREAS.  RANCHERS HAVE BEEN CULLING HERDS AT A GREATER THAN NORMAL
RATE IN THESE AREAS.  THE MAUI COUNTY DEPARTMENT OF WATER SUPPLY
CONTINUED ITS LONG STANDING REQUEST FOR A 5 PERCENT REDUCTION IN
WATER USE FOR UPCOUNTRY RESIDENTS.  THE REQUEST FOR A 10 PERCENT
REDUCTION IN WATER USE BY CENTRAL AND SOUTH MAUI RESIDENTS ALSO
REMAINED IN EFFECT.

BIG ISLAND.
IN EARLY DECEMBER WAILUKU RIVER AT RAINBOW FALLS STOPPED FLOWING BUT
RESUMED BY MID-DECEMBER AND AVERAGE FLOW WAS RECENTLY ABOVE THE 75TH
PERCENTILE. HOWEVER...CONDITIONS REMAIN VERY POOR FOR PASTURES AND
NON-IRRIGATED AGRICULTURE IN MOST OF THE KAU AND LEEWARD KOHALA
SECTIONS OF THE ISLAND. 

SPI values for seven time periods for Hawaiian Island stations, computed by the Honolulu NWS office.
SPI values for seven time periods for Hawaiian Island stations

On other Pacific Islands (maps — Micronesia, Marshall Islands, basinwide), December was drier than normal for Guam, Lukonor, Majuro, Pohnpei, and Saipan. December rainfall amounts were below four inches at Guam and Saipan and below 8 inches at Lukonor and Majuro. The reservoir on Majuro was at 50 percent capacity. Majuro has been below normal for 8 of the last 9 months. Total rainfall for the year (January-December 2012) was above normal for all stations except Koror, Majuro, and Pohnpei.


X
  • Percent of Normal Precip
  • Precipitation
  • Normals
Pacific Island Percent of 1981-2010 Normal Median Precipitation
Station NameJan
2012
Feb
2012
Mar
2012
Apr
2012
May
2012
Jun
2012
Jul
2012
Aug
2012
Sep
2012
Oct
2012
Nov
2012
Dec
2012
Jan 2012-
Dec 2012
Chuuk57%181%107%40%173%131%141%169%86%128%144%116%117%
Guam NAS162%94%215%121%224%107%66%179%126%92%74%55%100%
Kapingamarangi109%71%121%102%143%179%146%192%147%138%167%74%117%
Koror36%126%121%120%122%95%88%102%111%78%67%103%88%
Kosrae65%185%60%84%86%99%124%144%109%113%119%110%89%
Kwajalein134%114%84%68%161%117%120%95%57%73%45%230%97%
Lukonor86%124%135%76%106%125%82%73%148%74%178%62%90%
Majuro107%65%194%97%59%81%68%87%67%46%154%53%86%
Pago Pago61%98%131%90%126%115%105%59%195%54%181%143%99%
Pohnpei82%138%98%45%115%100%92%96%90%82%109%71%89%
Saipan77%183%35%33%166%118%77%135%101%172%31%89%106%
Yap33%117%185%89%142%99%84%128%187%140%121%102%115%
Pacific Island Precipitation (Inches)
Station NameJan
2012
Feb
2012
Mar
2012
Apr
2012
May
2012
Jun
2012
Jul
2012
Aug
2012
Sep
2012
Oct
2012
Nov
2012
Dec
2012
Jan 2012-
Dec 2012
Chuuk5.7413.138.875.0219.5615.2716.9221.7810.0414.6815.3013.09159.4
Guam NAS6.502.854.453.057.636.636.7426.4215.9810.565.452.8199.07
Kapingamarangi9.946.6113.8213.9117.2424.6820.6515.5714.5611.3215.447.25170.99
Koror3.6510.819.038.7914.4916.5416.3613.7213.019.237.6811.52134.83
Kosrae10.8923.939.5914.7015.3514.5618.5520.4615.5212.3316.4917.75190.12
Kwajalein4.223.011.973.5810.828.0811.839.236.178.185.0915.3387.51
Lukonor7.2211.0612.518.6012.3514.5313.0810.2615.028.3916.187.00136.2
Majuro8.274.4612.759.145.968.897.5410.157.475.8420.696.09107.25
Pago Pago8.1411.7614.008.4112.156.135.843.1912.734.9918.3418.31123.99
Pohnpei10.7513.1712.928.3122.9814.8614.2113.6211.2712.5916.1811.37162.23
Saipan1.964.750.660.883.964.266.8617.7310.2418.311.753.4474.8
Yap2.116.098.435.0011.1411.9512.7418.9225.1917.0810.678.68138
Pacific Island 1981-2010 Normal Median Precipitation (Inches)
Station NameJan
2012
Feb
2012
Mar
2012
Apr
2012
May
2012
Jun
2012
Jul
2012
Aug
2012
Sep
2012
Oct
2012
Nov
2012
Dec
2012
Jan 2012-
Dec 2012
Chuuk10.107.258.3212.4711.3011.6611.9812.8611.7111.5110.6111.25136.77
Guam NAS4.013.032.072.533.406.1810.1414.7412.6611.447.385.1199.09
Kapingamarangi9.159.2711.4313.6412.0813.7814.158.139.938.199.279.84145.85
Koror10.188.567.447.3211.8317.4818.5313.5011.7711.8411.3911.16152.90
Kosrae16.6712.9316.0617.5117.7514.6414.9114.2214.2210.9413.8316.11213.87
Kwajalein3.162.642.355.266.726.939.879.7410.7411.1811.286.6690.41
Lukonor8.418.939.2611.3111.6911.6515.9314.0410.1511.329.0811.27151.36
Majuro7.746.886.589.4210.1111.0111.1711.6911.1712.7313.4411.39125.25
Pago Pago13.3412.0010.689.399.665.335.555.386.539.2610.1412.84125.57
Pohnpei13.189.5513.1718.4119.9614.8115.4314.2612.5515.2714.8316.08182.36
Saipan2.532.591.892.632.383.628.9113.1310.0910.625.613.8570.25
Yap6.395.194.565.637.8512.0415.0814.8213.5012.188.838.51120.31

Percent of normal precipitation for current month for U.S. Affiliated Pacific Islant stations

SPI values for seven time periods for Pacific Islands, computed by the Honolulu NWS office.
SPI values for seven time periods for Pacific Islands

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State/Regional/National Moisture Status
A detailed review of drought and moisture conditions is available for all contiguous U.S. states, the nine standard regions, and the nation (contiguous U.S.):

States
alabama arizona arkansas california colorado connecticut
delaware florida georgia idaho illinois indiana
iowa kansas kentucky louisiana maine maryland
massachusetts michigan minnesota mississippi missouri montana
nebraska nevada new hampshire new jersey new mexico new york
north carolina north dakota ohio oklahoma oregon pennsylvania
rhode island south carolina south dakota tennessee texas utah
vermont virginia washington west virginia wisconsin wyoming

Regional
northeast u. s. east north central u. s. central u. s.
southeast u. s. west north central u. s. south u. s.
southwest u. s. northwest u. s. west u. s.

National
Contiguous United States

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Drought Indicators
The following indicators illustrate the drought conditions this month:

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Contacts & Questions
For additional, or more localized, drought information, please visit:

Global Snow & Ice

NH Snow Cover Extent

Data were provided by the Global Snow Laboratory, Rutgers University. Period of record is 1967-2012 (47 years).

The Northern Hemisphere snow cover extent (SCE) during December 2012 was much above average. The monthly SCE was 46.3 million square km (17.9 million square miles), which was 3.0 million square km (1.2 million square miles) above average and the largest December SCE on record for the hemisphere. The previous record large December SCE occurred in 1985 at 46.0 million square km.

During December, the North American SCE was above average, ranking as the 13th largest December SCE on record. The monthly SCE was 17.2 million square km (6.6 million square miles) — 579,000 square km (224,000 square miles) above the average of 16.6 million square km (6.4 million square miles). During the month, several storms impacted the western and central United States as well as western Canada bringing heavy snowfall. Above-average monthly snow cover was observed in the U.S. and Canadian Rockies and the U.S. Great Plains. Below-average snow cover was observed in the northeastern U.S. and southeastern Canada. For more information on the U.S. December 2012 snow events, please visit the U.S. December Snow/Ice Summary page.

Eurasian SCE was much above average during December. The monthly SCE of 29.1 million square km (11.2 million square miles) was 2.4 million square km (0.9 million square miles) above average and the second largest December SCE on record. The record largest Eurasian December SCE occurred in 2002 with 29.2 million square km (11.3 million square miles) of snow coverage. Above-average snow cover was observed for most of Europe, much of northern China, Mongolia, and Kazakhstan. Below-average snow cover was present in Turkey, the Tibetan Plateau, and the Himalayas.

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Sea Ice Extent

According to the National Snow and Ice Data Center (NSIDC), the Northern Hemisphere sea ice extent — which is measured from passive microwave instruments onboard NOAA satellites — averaged for December 2012 was 12.20 million square kilometers (4.71 million square miles), which was 8.70 percent below the 1979-2000 average and the second smallest December Arctic sea ice extent on record. December 2012 was the 18th consecutive December and 139th consecutive month with below-average Arctic sea ice extent. The smallest December snow cover extent occurred in 2010 at 12.02 million square km (4.6 million square miles). December Arctic ice extent is decreasing at an average rate of 3.4 percent per decade.

According to analysis by the NSIDC, the Arctic gained 2.33 million square km (900,000 square miles) of ice during December. Ice growth in the Kara and Barents seas was slower than average, leading to below average ice coverage there during the month. Sea ice in the Labrador Sea was also below average. Ice extent across the North Atlantic has been below-average for several consecutive winter seasons, and is related to higher mortality rates for seals in the region. The bearded and ringed seals were recently added to the list of threatened creatures under the Endangered Species Act. During December above-average ice extent was observed in the Bering Sea.

The December 2012 Southern Hemisphere sea ice extent was 11.28 million square km (4.4 million square miles), 1.5 percent above average, and the 16th smallest (18th largest) December sea ice extent in the 1979-2012 period of record. Antarctic sea ice extent during December has increased at an average rate of 1.9 percent per decade, with substantial interannual variability.

For further information on the Northern and Southern Hemisphere snow and ice conditions, please visit the NSIDC News page.

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Upper Air


Note: University of Alabama in Huntsville scientists advise that the AMSU channel 5 on the AQUA satellite, which has heretofore been the anchor-source of data in the construction of low- and mid-tropospheric temperatures (LT and MT) since 2002, was experiencing gradually increasing noise since 2009. However, a relatively rapid increase in noise in the recent few months to September 2012 generated clearly erroneous values. Therefore, beginning September 2012, these datasets (LT and MT) switched from AQUA to the AMSU channel 5 on NOAA-15 and NOAA-18, replacing AQUA data after 2009 in version 5.5.

Troposphere

Lower Troposphere

December Lower Troposphere
December Anomaly Rank
(out of 34 years)
Record Years Decadal Trend
°C °F Year °C °F °C °F
UAH +0.21 +0.38 Coolest 29th 1984 -0.48 -0.86 +0.12 +0.22
Warmest 6th 2003 +0.37 +0.67
RSS +0.02 +0.04 Coolest 17th 1984 -0.45 -0.81 +0.10 +0.18
Warmest 18th 2003 +0.37 +0.67
Year-to-Date Lower Troposphere
January–
December
Anomaly Rank
(out of 34 years)
Record Years Decadal Trend
°C °F Year °C °F °C °F
UAH +0.16 +0.29 Coolest 26th 1984 -0.35 -0.63 +0.14 +0.25
Warmest 9th 1998 +0.42 +0.76
RSS +0.09 +0.16 Coolest 24th 1985 -0.36 -0.65 +0.13 +0.24
Warmest 11th 1998 +0.45 +0.81

Mid-troposphere

December Mid-troposphere
December Anomaly Rank
(out of 34 years)
Record Years Decadal Trend
°C °F Year °C °F °C °F
UAH +0.08 +0.14 Coolest 22nd 1995 -0.27 -0.49 0.00 0.01
Warmest 11th 1987 +0.36 +0.65
Ties: 2009, 2001
RSS +0.15 +0.27 Coolest 29th 1985 -0.27 -0.49 +0.04 +0.07
Warmest 5th 1987 +0.37 +0.67
Ties: 1998
UW-UAH +0.14 +0.25 Coolest 28th 1983 -0.38 -0.68 +0.06 +0.11
Warmest 6th 1987 +0.38 +0.68
Ties: 1990
UW-RSS +0.20 +0.36 Coolest 30th 1983 -0.34 -0.61 +0.09 +0.16
Warmest 5th 1987 +0.39 +0.70
Year-to-Date Mid-troposphere
January–
December
Anomaly Rank
(out of 34 years*)
Record Years Decadal Trend
°C °F Year °C °F °C °F
UAH +0.01 +0.02 Coolest 17th 1984 -0.24 -0.43 +0.04 +0.08
Warmest 17th 1998 +0.42 +0.76
Ties: 1990
RSS +0.07 +0.13 Coolest 23rd 1985 -0.29 -0.52 +0.08 +0.14
Warmest 12th 1998 +0.43 +0.77
UW-UAH +0.07 +0.13 Coolest 24th 1984 -0.32 -0.58 +0.10 +0.19
Warmest 10th 1998 +0.52 +0.94
Ties: 2004
UW-RSS +0.12 +0.22 Coolest 25th 1985, 1984 -0.32 -0.58 +0.13 +0.24
Warmest 10th 1998 +0.51 +0.92
RATPAC* +0.20 +0.36 Coolest 47th 1965 -0.76 -1.37 +0.15 +0.27
Warmest 8th 2010 +0.48 +0.86
Ties: 2009

*RATPAC rank is based on 55 years of data

Stratosphere

December Stratosphere
December Anomaly Rank
(out of 34 years)
Record Years Decadal Trend
°C °F Year °C °F °C °F
UAH -0.37 -0.67 Coolest 10th 2000 -0.60 -1.08 -0.39 -0.71
Warmest 25th 1982 +1.45 +2.61
RSS -0.39 -0.70 Coolest 4th 2000 -0.56 -1.01 -0.33 -0.59
Warmest 29th 1982 +1.33 +2.39
Ties: 2006, 2005
Year-to-Date Stratosphere
January–
December
Anomaly Rank
(out of 34 years)
Record Years Decadal Trend
°C °F Year °C °F °C °F
UAH -0.42 -0.76 Coolest 3rd 2008 -0.48 -0.86 -0.37 -0.67
Warmest 32nd 1982 +1.04 +1.87
RSS -0.41 -0.74 Coolest 1st 2012 -0.41 -0.74 -0.30 -0.54
Warmest 34th 1992 +0.96 +1.73

Background Information

Temperatures above the Earth's surface are measured within the lower troposphere, middle troposphere, and stratosphere using in-situ balloon-borne instruments (radiosondes) and polar-orbiting satellites (NOAA's TIROS-N). The radiosonde and satellite records have been adjusted to remove time-dependent biases (artificialities caused by changes in radiosonde instruments and measurement practices as well as changes in satellite instruments and orbital features through time). Global averages from radiosonde data are available from 1958 to present, while satellite measurements date back to 1979.

The mid-troposphere temperatures are centered in the in the atmospheric layer approximately 3–10 km [2–6 miles] above the Earth's surface, which also includes a portion of the lower stratosphere. (The Microwave Sounding Unit [MSU] channel used to measure mid-tropospheric temperatures receives about 25 percent of its signal above 10 km [6 miles].) Because the stratosphere has cooled due to increasing greenhouse gases in the troposphere and losses of ozone in the stratosphere, the stratospheric contribution to the tropospheric average, as measured from satellites, creates an artificial component of cooling to the mid-troposphere temperatures. The University of Washington (UW) versions of the UAH and RSS analyses attempt to remove the stratospheric influence from the mid-troposphere measurements, and as a result the UW versions tend to have a larger warming trend than either the UAH or RSS versions. For additional information, please see NCDC's Microwave Sounding Unit page.

The radiosonde data used in this global analysis were developed using the Lanzante, Klein, Seidel (2003) ("LKS") bias-adjusted dataset and the First Difference Method (Free et al. 2004) (RATPAC). Additional details are available. Satellite data have been adjusted by the Global Hydrology and Climate Center at the University of Alabama in Huntsville (UAH). An independent analysis is also performed by Remote Sensing Systems (RSS) and a third analysis has been performed by Dr. Qiang Fu of the University of Washington (UW) (Fu et al. 2004)** to remove the influence of the stratosphere on the mid-troposphere value. Global averages from radiosonde data are available from 1958 to present, while satellite measurements began in 1979.

References

Wildfires

Updated: 15 January 2013


Overview

Wildfire activity was generally light throughout the country during December. Isolated incidents of large fires occurred in the West while scattered activity continued along the Appalachian Mountains in the East during the first half of the month. Large fire activity flared in eastern Oklahoma during the latter half of December.

Although the number of fires rose dramatically for the month, the average fire size in December became extremely small because the amount of acres burned stayed relatively low. December's reversal (many fires of small size) was not enough to overturn the year-to-date pattern for incidents of fewer fires with larger size. The monthly total number of 11,760 fires was the most for December in the thirteen-year record and over 2.5 times the 10-year average (based on 2001-2010). Nonetheless, the year-to-date total of 67,265 fires was the 4th least since 2000 for any January through December period.

The monthly average fire size of 5.6 acres per fire was the least on record for any December in the 2000-2012 record and far below the 10-year average of 41.2 acres per fire. Yet, the year-to-date average fire size of 137.1 acres was the most since 2000 for any January through December period, and about 1.5 times the 10-year average (based on 2001-2010). The December acres burned represented about one-third of the month's 10-year average (based on 2001-2010) acres burned. The monthly total of 65,361 acres burned by wildfires ranked at the 2nd least amount for any December since 2000. Yet, the year-to-date total acreage burned of 9.2 million acres was the 3rd most since 2000 and represented about 1.5 times the 10-year average (based on 2001-2010).

1-Month Wildfire Statistics*
December Totals Rank
(out of 13 years)
Record 2000-2010
Average
Value Year
Acres Burned 65,361 12ᵗʰ Most 427,160 2007 178,037
2ⁿᵈ Least
Number of Fires 11,760 Most on Record 11,760 2012 4,110
13ᵗʰ Least
Acres Burned per Fire 5.6 13ᵗʰ Most 72.3 2000 44.1
Least on Record
Year-to-Date Wildfire Statistics*
January–December Totals Rank
(out of 13 years)
Record 2000-2010
Average
Value Year
Acres Burned 9,221,639 3ʳᵈ Most 9,873,745 2006 6,612,363
11ᵗʰ Least
Number of Fires 67,265 10ᵗʰ Most 96,385 2006 77,951
4ᵗʰ Least
Acres Burned per Fire 137.1 Most on Record 137.1 2012 85.2
13ᵗʰ Least

*Data Source: The National Interagency Fire Center (NIFC)

Discussion

Despite the multiple passages of winter storms across the country throughout December, the precipitation received was not enough to ease long-term deficits. Exceptional drought remained entrenched over the central Great Plains, keeping the wildland fire potential high for the states of Nebraska, Wyoming, Colorado, Kansas, Oklahoma, Texas, and New Mexico. Drought expanded in eastern Wyoming, central Oklahoma, and parts of Texas. At mid-month, precipitation across northern California, Idaho, and northwestern Wyoming brought about improved conditions. In the latter part of December, rains in the Southeast resulted in a lessening of the drought in central Alabama and northern Georgia. Dryness contracted in upstate New York by month's end as beneficial rains fell in the Northeast.

Significant Events


Please note, this is a list of select fires that occurred during December. Additional fire information can be found through Inciweb.


Oklahoma

Persistent extreme drought conditions in eastern Oklahoma were conducive to wildfire activity throughout the month. In early December, the Indian Springs wildfire blazed at least 122 acres of hardwoods to the west of Spavinaw. At mid-month, several fires erupted along the border with Arkansas, with at least 8 large incidents burning on December 21st. The Peachland wildfire ignited on December 16th to the northwest of Talihina and consumed 450 acres. The Sonny Hollar wildfire scorched 350 acres southeast of Stilwell after sparking on December 19th. The remaining fires ranged between 100 and 200 acres apiece. In the final week of December, the Elk Trail wildfire burned 360 acres.

Raspberry Mountain Fire on 01 December 2012Raspberry Mountain Fire
on 01 December 2012
Source: USFS

Arkansas

Wildfires continued in northwestern Arkansas during December. The Raspberry Mountain wildfire was ignited by lightning in the rugged, steep terrain near the Shady Lake Recreation Area. The blaze consumed over 870 acres of hardwoods from November 26th through December 17th until a series of rains extinguished its flames. Heavy smoke closed a portion of Highway 103 near Clarkson due to a 200-acre wildfire on December 14th.

Monthly Wildfire Conditions

Wildfire information and environmental conditions are provided by the National Interagency Fire Center (NIFC) and the U.S. Forest Service (USFS) Wildland Fire Assessment System (WFAS).

At the start of December, extremely low 10-hour fuel moistures (from 3 to 4 percent) existed in central Colorado, southwestern New Mexico and the southeastern corner of Arizona. Critical fire weather conditions (gusty winds, low humidity, warm temperatures) in southern California were aligned with high Keetch-Byram Drought Index (KBDI) values (> 600 units). Fuel moistures from 5 to 6 percent reached northward over the High Plains and Rockies. Wildfire incidents coincided with a pocket of low 10-hour fuel moistures (from 9 to 10 percent) in southwestern Virginia, near the Kentucky border. The Skegg Again wildfire charred over 820 acres of hardwoods on the Pine Mountain in Dickenson County of Virginia and threatened 18 homes. In Tennessee, the Shack's Creek wildfire consumed almost 1,000 acres, while the Cross Mountain wildfire blazed 100 acres. Utah and the areas from central Texas to the Great Lakes experienced low 100-hour fuel moistures (from 11 to 15 percent), while lower fuel moistures (from 6 to 10 percent) at both the 100-hour and 1000-hour intervals dominated the central Rockies, High Plains, northern and central Great Plains, and New Mexico. In northeastern Kansas, the Calfex Complex wildfire consumed over 6,200 acres in Riley County.


Central Arizona received precipitation ranging from 1.5 to 3.0 inches over several days at mid-month, which raised the 10-hour fuel moisture to above 25 percent. At both the 100-hour and 1000-hour intervals, fuel moistures increased across the High Plains and Southwest, although parts of Colorado, eastern Oklahoma, and west Texas remained at or below 10 percent. As more than a foot of snow dropped over northern Colorado on December 18th, the spread of the Fern Lake Fire was halted. Having burned since early October, the fire doubled its size in early December when high winds fanned the flames. Deep and dense duff combined with beetle-killed timber to fuel the fire, which consumed almost 3,500 acres in total. During December, the fire forced the evacuation of nearly 200 area residents and one cabin was lost. Critical fire weather existed along the Texas and New Mexico border as a result of a lack of moisture and unseasonably warm temperatures. Dry conditions in central Texas contributed to a sizable grass fire in Manor, which ignited on December 21st.


At month's end, the influx of precipitation resulted in fuel moistures at all intervals (10-hour, 100-hour, and 1000-hour) being at 6 percent or more for the entire country. At the 10-hour interval, fuel moistures in southern California and the central Carolinas were the lowest (from 7 to 8 percent) nationally. At the 1000-hour interval, only far west Texas' fuel moistures remained as lowest with values from 6 to 10 percent. The remaining large fires in Oklahoma were fully contained.


All Fire Related Maps


Citing This Report

NOAA National Climatic Data Center, State of the Climate for December 2012, published online January 2013, retrieved on July 25, 2014 from http://www.ncdc.noaa.gov/sotc/2012/12.