Entire Report - Annual 2008


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.

U.S. Annual Temperature timeseries
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National Temperatures

Based on data through the end of 2008, the contiguous U.S. experienced a nationally averaged temperature that was the coolest in more than ten years. The average temperature of 53.0°F (11.7°C) was 0.2°F (0.1°C) above the 20th century (1901-2000) mean.

The average temperature for the U.S. has not been this close to the 20th century mean since 1997. The January - December statewide temperature ranking map for 1997 display a close resemblance to the 2008 map. The anomalous warmth that the contiguous U.S. has seen the past 10 years was generally isolated within the West, Southwest, and Northeast Regions during 2008. In contrast, the Central and East North Central regions of the U.S. were below the 20th century mean. This resulted in a near normal nationally averaged temperature of 53.0°F (11.7°C).

2008 National Annual Temperature Rank Map

Seasonal Analysis:

The 2007-2008 winter season (December-February) was the 53rd warmest such period on record (1896-2008), with warmer-than-average temperatures along the South, Southeast and Northeast. Winter temperatures were below normal in the East North Central, Southwest, and West regions.

Spring 2008 (March-May) was the 45th coolest for the nation, with below average temperatures across the central Plains and westward. Rhode Island was 11th warmest on record during this period.

The contiguous U.S. experienced a warmer-than-normal summer (June-August), as the nation ranked 30th warmest in the last 114 years. Much above average temperatures were limited to the west, where California experienced their 6th warmest summer on record, and in the Northeast, where New Jersey experienced their 8th warmest summer and Rhode Island experienced their 6th warmest summer on record.

Temperature averages during the fall (September-November) for the western U.S. were above normal, while the eastern U.S. had below normal averages. California experienced the 3rd warmest fall on record. Arizona, Nevada, and Utah were much above normal during the period as well. This contrasted greatly with the South and Southeast where Georgia saw their 8th coolest fall period on record and both South Carolina and Mississippi experienced their 10th coolest fall. The resulting 2008 fall season (September-November) ranked 32nd warmest nationally.

For the January-December 2008 period, cooler-than-average temperatures affected much of the Central, East North Central, and parts of the South regions, while warmer than average temperatures affected the Southwest, West, and portions of the Northeast regions. This resulted in the 39th warmest January-December in the 114-year record nationally. New Jersey experienced their 10th warmest and Delaware had their 11th warmest annual period. Conversely, Iowa had their 11th coolest annual period.

Annual temperatures across the state of Alaska during 2008 averaged approximately 0.7°F (0.4°C) below normal. Winter temperatures in 2007-2008 were near average. Spring was the 29th warmest on record with with a temperature 1.0°F (0.6°C) above average, Summer was 1.0 °F (0.6°C) cooler than average, and Fall was more than 2.0°F (1.1°) cooler than the 1971-2000 average.


The percent area of the contiguous United States very warm and very cold during each of the past 48 months is listed in the figure to the left. These percentages are computed based on the climate division data set. Those climate divisions having the monthly average temperature in the top ten percent (> 90th percentile) of their historical distribution are very warm and those in the bottom ten percent (< 10th percentile) are very cold.

The U.S. did not see any massive warm or cold outbreaks during 2008 and only once in 2008 (November) did 20% or more of the U.S. experienced very warm monthly average temperatures.

Below average temperatures were measured in the lower troposphere for the first time in more than 10 years. Data collected by NOAA's TIROS-N polar-orbiting satellites and adjusted for time-dependent biases by NASA and the Global Hydrology and Climate Center at the University of Alabama in Huntsville, indicate that temperatures in the lower half of the troposphere (lowest 8 km of the atmosphere) over the U.S. were slightly cooler than the 20-year (1979-1998) average.

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National Precipitation

Precipitation in the United States during 2008 was variable throughout much of the country with periods of excessive rainfall, especially across the central third of the country. The western U.S. remained parched, while the drought conditions lessened in the Southeast. The Northeast region averaged 50.04 inches (1,274 mm) of precipitation in 2008 which was 9.06 inches (230 mm) above the 20th century (1901-2000) average. New Hampshire experienced their 5th consecutive year with above average precipitation with 19.84 inches (504mm). It was their wettest on record, breaking the previous record set just four years prior. Missouri also experienced their wettest year on record with 57.28 inches (1455 mm) of precipitation, which was 16.52 inches (420 mm) above average.

Precipitation during the December 2007 - February 2008 period was above normal for much of the contiguous U.S. as it was the 16th wettest winter on record. In the spring an average of 8.0 (203 mm) inches of precipitation fell across the U.S., making the season the 42nd wettest on record. California had the driest spring on record, while Nevada and Utah had their 10th and 11th driest springs on record, respectively, Missouri had their fourth wettest spring and Arkansas, Indiana and Iowa all experienced a wet period that ranked in the top 10 on record. The summer brought an average of 8.0 inches (203 mm) of precipitation across the U.S., however much of the precipitation occurred in the eastern two-thirds of the country. It was the 53rd driest fall on record for the nation. The precipitation pattern for much of the contiguous United States was comprised of both wet and dry extremes which resulted in a near normal average for the period.

For the contiguous U.S. every month, with the exceptions of October and November, was near to above average in 2008. The increased precipitation during 2008 helped ease some of the drought stricken areas across the U.S. According to the U.S. Drought Monitor, the percent area of severe to extreme drought decreased by approximately 25% in the West. The severe to extreme conditions in the Southeast decreased by more than 50%. The average annual precipitation for 2008 was 30.48 inches (774 mm), which is 1.34 inches (34 mm) above the 20th century (1901-2000) average.

Seasonal Analysis:

Nationally, this was the 18th wettest winter (December-February) in the 1895-2008 record. The state of New York recorded its wettest winter on record, and the states of Colorado, Connecticut, Pennsylvania, and Vermont experienced their second wettest winter on record. The South region received below normal levels of precipitation, mostly due to a dry winter in Texas.

California had their driest spring (March-May) on record, while Nevada and Utah had their 10th and 11th driest springs on record, respectively. Conversely, parts of the central Mississippi valley received much above normal precipitation during the spring. Missouri experienced the fourth wettest spring, Arkansas the sixth, Indiana and Iowa the eighth wettest, and Illinois the tenth wettest spring in the 1895-2008 record.

Both Florida and New Hampshire experienced their wettest summer (June-August) on record in 2008. The Northeast as a whole experienced their ninth wettest summer on record as Maine, Vermont, New York, Massachusetts, and Connecticut were much above normal. Iowa had their seventh wettest summer on record. Below normal precipitation was confined to areas in the West and East. Tennessee, New Jersey, Delaware, and California all experienced a below normal summer which ranked in the bottom 25.

This was the 53rd driest fall (September-November) in the 1895-2008 record nationally. An average of 6.7 inches (169.1 mm) of precipitation fell across the contiguous U.S., which is 0.1 inch (1.2 cm) below average. Nebraska experienced its third wettest fall on record and the state of Kentucky experienced its 11th driest fall on record. On the regional level, the West North Central received much above normal precipitation, while the Southwest and East North Central regions received below normal precipitation.


The percent area of the contiguous United States very wet and very dry during each of the last 48 months is listed in the adjacent figure. These percentages are computed based on the climate division data set. Those divisions having the monthly total precipitation in the top ten percent are very wet and those in the bottom ten percent are very dry. In 2008, a tenth or more of the country was very dry during March, April, and September.

During February-September of 2008, a tenth or more of the country was very wet. The highest monthly percentage seen during 2008 was in August when 19% of the U.S. was very wet.

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Severe Storms

According to NOAA's Storm Prediction Center, preliminary estimates indicate that there were 2,192 reported tornadoes from January-December 2008, which is well above the ten-year average of 1,270. Of these tornadoes, 36 were rated EF3-EF5, which is equivalent to the average number of strong to violent tornadoes which have been reported over the period 1950-2008. Note that these numbers represent preliminary tornado reports and not the final number of total tornadoes.

The beginning of 2008 was an active severe weather period. There were 54 confirmed reports of tornadoes and five deaths across the Midwest between January 7th and 8th, making it the second largest January tornado outbreak on record. On February 5th, while 24 states held primary elections, 87 tornadoes occurred. This deadly event, nicknamed the "Super Tuesday Outbreak", caused 57 deaths in the southeastern U.S. for a total of 58 nationally in the month of February. The number of tornado related fatalities reported in February was the second highest on record for the month.

May was also an active month with 460 confirmed tornadoes, making it the third most active May on record. For the period January through May, a total of 112 tornado fatalities were reported. This year shares the record with 1968 as the eighth deadliest January through May period since reliable records began in 1953. Severe weather continued into June when two outbreaks spawned 289 confirmed tornadoes.

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Atlantic Hurricanes

The 2008 Atlantic basin hurricane season was above the 1950-2000 average with 16 named storms, of which eight were hurricanes, including five major hurricanes. The ACE index of hurricane activity indicated an above-average season, with a preliminary value of approximately 142 x104 knots2. In terms of accumulated cyclone energy (based on integrated wind power of all tropical cyclones during the season, both landfalling and those remaining out at sea), 2008 ranked as the 16th most energetic season out of the last 59.

The first 2008 Atlantic storm to make landfall in the U.S. was Hurricane Dolly. The storm made landfall in South Padre Island, Texas on July 23rd. While there were no direct deaths from the hurricane, it caused an estimated $1.2 billion of damage. Tropical Storm Fay was the first storm in recorded history to make landfall four times in a single state. Fay first made landfall in southern Florida on August 18th and continued to batter Florida through the 21st. Thirty-six deaths were blamed on the tropical storm and damages are estimated to exceed $180 million.

On August 25th, Hurricane Gustav formed in the South Caribbean as the season's second major hurricane. Hurricane Bertha on July 3rd was the season's first. Hurricane Gustav first made landfall in Haiti and again in western Cuba. On September 1st, Gustav made U.S. landfall in Louisiana as a category 2 hurricane. Gustav was blamed for a total of 138 deaths in the U.S. and the Caribbean and resulted in an estimated $4.3 billion of damage in the U.S.

As Gustav made landfall, Hurricane Ike began to form in the eastern Atlantic. Facilitated by favorable atmospheric conditions, Ike was able to quickly intensify into a category 4 hurricane on September 4th. On the 7th, while trying to recover from three earlier storms (Fay, Gustav, and Hanna), Cuba was hit again with winds estimated at 127-132 mph (203-213 km/h or 110-115 knots). Ike made U.S. landfall at Galveston, Texas, on September 13th as a category 2 hurricane. One-hundred-sixty-four deaths were blamed on Ike and damage estimates totaled more than $30 billion in the U.S., Cuba, and Bahamas, making Ike the third costliest hurricane of all time behind Andrew and Katrina.

Hurricane Paloma was the last major hurricane in the 2008 Atlantic Basin season. It was also the third major hurricane to hit Cuba (Gustav and Ike). This marks the first time on record that Cuba was struck by three major hurricanes in one season. Paloma made landfall in Santa Cruz del Sur, Cuba on November 8th and caused an estimated $1.4 billion of damage.

This year was the only year on record in which a major hurricane existed in every month from July through November in the North Atlantic (Bertha, Gustav, Ike, Omar, and Paloma). On July 20th, there were three active storms: Hurricane Bertha, and Tropical Storms Cristobal and Dolly. This was the earliest known date for three storms to be active on the same day. It is also noteworthy that none of the five major hurricanes (category 3 and above) were of major status at the time of U.S. landfall. This information is based on preliminary data and is subject to change. More details about these and all the 2008 Atlantic tropical systems can be found on NCDC's Atlantic hurricane page.

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Snow Season

The 2007-2008 snow season began with above average snowfall across parts of the Southwest and well-below-normal amounts in the Sierra Nevada, Cascades, and the Bear (ID, UT) and Salt River Ranges. A major ice storm struck parts of the south-central U.S. in the second week of December 2007, leaving over 600,000 residents in Oklahoma without power and causing over 20 fatalities across five states, prompting the governor to declare the ice storm the worst in Oklahoma history.

The same system later brought heavy amounts of snow to the Northeast, slamming Boston with up to ten inches (25.4 cm) on December 13th. As many residents began to clear out from the last storm, another strong upper-level system moved across the central U.S. through New England between December 15th-17th, bringing ice, sleet, damaging winds, and as much as 18 inches (45.7 cm) of snow in some areas. Detroit, MI, received 9.0 inches (22.9 cm) of snow, tying it as the 9th biggest December snowstorm on record. By the 17th, the total snowfall (19.6 inches/49.8 cm) in Boston, MA was more than the total snowfall of 2006-2007 (17.1 inches/43.4 cm).

February brought a series of large winter storms across much of the northern two-thirds of the U.S. By the end of the month, Boston's Logan International Airport broke a new February record for total precipitation, and parts of Wisconsin also set new seasonal snowfall records. In March, several additional cities broke seasonal snowfall records. Madison, WI set a new record for seasonal snow total of 100.1 inches (254.2 cm) on March 24, breaking the previous record of 76.1 inches (193.3 cm) from the 1978-79 season. Milwaukee, WI had its second snowiest winter on record as of March 24th. The seasonal snowfall total in Caribou, ME on March 21nd reached a new all-time record when the 2007-2008 total of 184.5 inches (468.6 cm) surpassed the previous record of 181.1 inches (460.0 cm) set during the 1954-55 snowfall season. By the end of the month, the snowfall total at Caribou was 190.7 inches (484.4 cm). Snowfall records at Caribou began in 1939. By the end of March, the winter of 2007-2008 in Concord, NH ranked as the second snowiest on record, only six inches (15 cm) shy of the all-time seasonal record of 122 inches (310 cm) set in the winter of 1873-74.

During the winter of 2007/2008, the snowpack levels were above-average in much of the Rockies, Cascades, and Sierra Nevada in the western U.S. At times, some areas in Oregon, Washington, Arizona, New Mexico, Nevada and southern Colorado had levels above 180% of normal. Conversely, parts of Wyoming, Montana, Nevada and north-central Washington had levels below normal, as did much of eastern Alaska and southern New Mexico. Above-average snowfall during the 2007-2008 season brought relief to many areas of the western U.S. that were plagued by drought in previous years.


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NOAA's National Climatic Data Center is the world's largest active archive of weather data. The preliminary temperature and precipitation rankings are available from the center by calling: 828-271-4800.

NOAA works closely with the academic and science communities on climate-related research projects to increase the understanding of El Niño and improve forecasting techniques. NOAA's Climate Prediction Center monitors, analyzes and predicts climate events ranging from weeks to seasons for the nation. NOAA also operates the network of data buoys and satellites that provide vital information about the ocean waters, and initiates research projects to improve future climate forecasts.

Global Analysis

2008 Global Temperature Anomalies

PLEASE NOTE: The ranks and temperature anomalies in this report represent the values known at the time the report was issued. The actual ranks will change as subsequent years are added to the dataset. The anomalies themselves may change slightly as missing or erroneous data is resolved. Also, in 2009, NCDC switched to ERSST version 3b (from version 2) as a component of its global surface temperature dataset. Because the versions have slightly different methodologies, the calculated temperature anomalies will differ slightly. For more information about this switch please see the Global Surface Temperature Anomalies FAQ .

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Global Temperatures

The global January-December temperature for combined land and ocean surfaces was 0.49°C (0.88°F) above the 20th century average, tying with 2001 as the eighth warmest since records began in 1880. Globally averaged land temperatures were 0.81°C (1.46°F) above average, while the ocean temperatures were 0.37°C (0.67°F) above average, ranking as the sixth warmest and tenth warmest, respectively. Eight of the ten warmest years on record have occurred since 2001, part of a rise in temperatures of 0.5°C (0.9°F) since 1880. See the global time series.

Global Top 10 Warm Years (Jan-Dec) Anomaly °C Anomaly °F
2005 0.61 1.10
1998 0.58 1.04
2002 0.56 1.01
2003 0.56 1.01
2006 0.55 0.99
2007 0.55 0.99
2004 0.53 0.95
2001 0.49 0.88
2008 0.49 0.88
1997 0.46 0.83

The year began with a cold phase (La Niña) El Niño-Southern Oscillation (ENSO) which developed during late 2007, transitioned to a neutral phase in June 2008, and remained neutral through the end of the year. The presence of a strong La Niña dampened ocean sea surface temperatures (SSTs) and contributed to a February global average temperature that was the coolest since the La Niña episode of 2000-2001. During March, sea surface temperature (SST) anomalies were cooler-than-average in all Niño regions, with the exception of the Niño 1+2 region where the monthly temperature anomaly rose to +0.82°C (+1.48°F). Temperatures across Niño 3.4 and Niño 4 regions increased slightly but the anomalies remained below average. These conditions indicated the first signs of weakening of the cold event (La Niña), however a moderate La Niña remained across the equatorial Pacific Ocean. By June, temperatures across the Niño 3.4 and Niño 4 regions continued to warm and the Oceanic Niño Index threshold [3-month (April-June) running mean] was -0.50°C (-0.90°F), indicating a transition into a neutral phase. By the end of December, neutral phase ENSO conditions persisted across the equatorial Pacific Ocean, although characteristics of a developing La Niña were present. According to the latest information from NOAA's Climate Prediction Center, La Niña conditions could develop into early 2009. For more information on the state of ENSO during 2008, please see the ENSO monitoring annual summary.

January-
December
Anomaly Rank Warmest Year on Record

Global

Land
Ocean
Land and Ocean

+0.81°C (+1.46°F)
+0.37°C (+0.67°F)
+0.49°C (+0.88°F)

6thwarmest
10th warmest
8th warmest

2007 (+1.02°C/1.84°F)
2003 (+0.48°C/0.86°F)
2005 (+0.61°C/1.10°F)

Northern Hemisphere

Land
Ocean
Land and Ocean


+0.89°C (+1.60°F)
+0.40°C (+0.72°F)
+0.59°C (+1.06°F)


5th warmest
9th warmest
8th warmest


2007 (+1.18°C/2.12°F)
2005 (+0.54°C/0.97°F)
2005 (+0.72°C/1.30°F)

Southern Hemisphere

Land
Ocean
Land and Ocean


+0.54°C (+0.97°F)
+0.35°C (+0.63°F)
+0.38°C (+0.68°F)


6th warmest
10th warmest
9th warmest


2005 (+0.81°C/1.46°F)
1998 (+0.50°C/0.90°F)
1998 (+0.53°C/0.95°F)

The 1901-2000 average combined land and ocean annual temperature is 13.9°C (56.9°F), the annually averaged land temperature for the same period is 8.5°C (47.3°F), and the long-term annually averaged sea surface temperature is 16.1°C (60.9°F).

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Regional Temperatures

Warmer-than-average temperatures occurred throughout the year in most land areas of the world, with the exception of cooler-than-average conditions across Colombia, parts of Alaska, central Canada, and the midwestern continental U.S. The warmest above-average temperatures occurred throughout high latitude regions of the Northern Hemisphere including much of Europe and Asia. Temperature anomalies in these regions ranged from 2-4°C (3.6-7.2°F) above the 1961-1990 average.

The map, above left, is created using data from the Global Historical Climatology Network (GHCN), a network of more than 7,000 land surface observing stations. The map, above right, is a product of a merged land surface and sea surface temperature anomaly analysis developed by Smith and Reynolds (2005). Temperature anomalies with respect to the 1961-1990 mean for land and ocean are analyzed separately and then merged to form the global analysis. Additional information on this product is available.

Notable temperature extremes in 2008 include the below average temperatures across the Middle East, central Asia, and southeast China during January 2008. Parts of Turkey experienced their coldest January nights in 50 years (WMO). Freezing temperatures and heavy snowfall affected over 78 million people and resulted in 60 fatalities across China. The anomalously cool conditions over central Asia and southeast China were associated with the largest January snow cover extent on record for the Eurasian continent and for the Northern Hemisphere. In contrast, above average temperatures during January were observed across Australia, Europe, and northern Asia. Temperatures in Australia were 3-5°C (5-7°F) above average across large areas in Western and Central Australia. For the nation as a whole, the January 2008 average temperature was 1.23°C (2.21°F) above the 1961-1990 mean, making it the warmest January on record [Australia's Bureau of Meteorology(BoM)]. Most parts of the Fenno-Scandinavia region had their warmest winter since records began (WMO).

In March, South Australia experienced a record heat wave which brought scorching temperatures across the state. Adelaide, South Australia's capital, experienced its longest running heat wave on record, with 15 consecutive days of maximum temperatures above 35°C (95°F). This shattered the previous record of 8 consecutive days which was tied on numerous occasions, most recently in February 2004. Also, Adelaide set a new record as having the longest number of consecutive days exceeding 35°C (95°F) for all Australian state capital cities. The second longest such streak was 10 days, set in February 1988 in the city of Perth. Overall, South Australia had its third warmest March since records began with 2.35°C (4.23°F) above the 1961-1990 average (BoM).

During the second and third weeks of September, Hungary saw a marked contrast in temperatures. The city of Szeged set a new maximum temperature record for September 7 when temperatures rose to 37.6°C (100°F), surpassing the 1946 record of 36.7°C (98°F). Meanwhile, on September 15, a new national record was set when the city of Sopron, Hungary recorded its coldest temperature of 8.6°C (47°F), surpassing the previous record set in Zalaegerszeg in 1925 when temperatures fell to 10.5°C (51°F).

Additional information on other notable weather events can be found in the Significant Events section of this report.

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Global Precipitation

Global precipitation in 2008 was above the 1961-1990 average. Precipitation throughout the year was variable in many areas. Regionally, drier than average conditions were widespread across the Hawaiian Islands, the western and south-central contiguous U.S., southwestern Alaska, southeastern Africa, southern Europe, northern India, and parts of Argentina, Uruguay, eastern Asia, the eastern coast of Brazil, and southern Australia. Most of Europe, western Africa, the northeastern and central contiguous U.S., parts of northern South America and southeastern Asia experienced wetter than average conditions.

The Philippine Islands received much-above-average precipitation in 2008 due to several tropical cyclones that made landfall in the region during the active season, dumping heavy precipitation which led to widespread floods and landslides on the islands. In southern China, severe storms and Typhoon Fengshen brought heavy rain across the area, causing widespread floods and landslides. The copious rainfall across southern China made June 2008 the wettest month on record for Hong Kong, Guangzhou, and Macao, according to the Hong Kong Observatory. Records began in 1884.

Precipitation across Australia was 73 percent below normal during May, resulting in the driest May on record. May 2008 had a national average of 7.86 mm (0.31 inches) of rain, supplanting the 1961 record of 8.27 mm (0.32 inches). During March-May, Australia, as a whole, experienced 53 percent below-normal precipitation, resulting in the eighth driest austral autumn (March-May). Parts of Australia have been experiencing drought conditions for over a decade.

In the U.S., heavy rain fell across much of the Midwest during the first half of June, causing the worst floods in 15 years and setting numerous new record river crest levels. For more information, please visit the June Midwest Flooding page.

Unsettled weather affected the British Isles during the boreal summer (June-August), resulting in a summer rainfall total that was much above the 1971-2000 mean. June-August 2008 period ranked as one of the top 10 wettest summers since records began there in 1914. Northern Ireland experienced its second wettest boreal summer when a total of 393.7 mm (15.5 inches) of rain fell. The wettest boreal summer for Northern Ireland was set in 1958 when 404.0 mm (15.9 inches) of rain fell.

Prolonged drought (January-September) across parts of Argentina, Paraguay, and Uruguay significantly affected agriculture. Some areas experienced their worst drought in over five decades.

During September 2008, Hurricanes Gustav, Hanna, and Ike, and Tropical Storm Kyle brought torrential rain across the Caribbean and parts of the continental U.S., triggering fatal floods and wreaking havoc across the affected areas.

For more information about precipitation extremes during 2008, see the annual report of Significant Events.

Additional information on other notable weather events can be found in the Significant Events section of this report.

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NOAA's National Climatic Data Center is the world's largest active archive of weather data. The temperature and precipitation rankings are available from the center by calling: 828-271-4800.


NOAA works closely with the academic and science communities on climate-related research projects to increase the understanding of El Niño and improve forecasting techniques. NOAA's Climate Prediction Center monitors, analyzes and predicts climate events ranging from weeks to seasons for the nation. NOAA also operates the network of data buoys and satellites that provide vital information about the ocean waters, and initiates research projects to improve future climate forecasts.

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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.

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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.


The 2007-2008 snow season began with above average snowfall across parts of the Southwest and well-below-normal amounts in the Sierra Nevada, Cascades, and the Bear (ID, UT) and Salt River Ranges. A major ice storm struck parts of the south-central U.S. in the second week of December 2007, leaving over 600,000 residents in Oklahoma without power and causing over 20 fatalities across five states, prompting the governor to declare the ice storm the worst in Oklahoma history.

The same system later brought heavy amounts of snow to the Northeast, slamming Boston with up to ten inches (25.4 cm) on December 13th. As many residents began to clear out from the last storm, another strong upper-level system moved across the central U.S. through New England between December 15th-17th, bringing ice, sleet, damaging winds, and as much as 18 inches (45.7 cm) of snow in some areas. Detroit, MI, received 9.0 inches (22.9 cm) of snow, tying it as the 9th biggest December snowstorm on record. By the 17th, the total snowfall (19.6 inches/49.8 cm) in Boston, MA was more than the total snowfall of 2006-2007 (17.1 inches/43.4 cm).

February brought a series of large winter storms across much of the northern two-thirds of the U.S. By the end of the month, Boston's Logan International Airport broke a new February record for total precipitation, and parts of Wisconsin also set new seasonal snowfall records. In March, several additional cities broke seasonal snowfall records. Madison, WI set a new record for seasonal snow total of 100.1 inches (254.2 cm) on March 24, breaking the previous record of 76.1 inches (193.3 cm) from the 1978-79 season. Milwaukee, WI had its second snowiest winter on record as of March 24th. The seasonal snowfall total in Caribou, ME on March 21nd reached a new all-time record when the 2007-2008 total of 184.5 inches (468.6 cm) surpassed the previous record of 181.1 inches (460.0 cm) set during the 1954-55 snowfall season. By the end of the month, the snowfall total at Caribou was 190.7 inches (484.4 cm). Snowfall records at Caribou began in 1939. By the end of March, the winter of 2007-2008 in Concord, NH ranked as the second snowiest on record, only six inches (15 cm) shy of the all-time seasonal record of 122 inches (310 cm) set in the winter of 1873-74.

During the winter of 2007/2008, the snowpack levels were above-average in much of the Rockies, Cascades, and Sierra Nevada in the western U.S. At times, some areas in Oregon, Washington, Arizona, New Mexico, Nevada and southern Colorado had levels above 180% of normal. Conversely, parts of Wyoming, Montana, Nevada and north-central Washington had levels below normal, as did much of eastern Alaska and southern New Mexico. Above-average snowfall during the 2007-2008 season brought relief to many areas of the western U.S. that were plagued by drought in previous years.

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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 NOAA's Storm Prediction Center, preliminary estimates indicate that there were 2192 reported tornadoes from January-December 2008, which is well above the ten-year average. Of these tornadoes, 36 were rated EF3-EF5, which is equivalent to the average number of strong to violent tonadoes which have been reported over the period 1950-2008. Note that these numbers represent preliminary tornado reports and not the final number of total tornadoes.

The beginning of 2008 was an active severe weather period. There were 54 confirmed reports of tornadoes and five deaths across the Midwest between January 7th and 8th, making it the second largest January tornado outbreak on record. On February 5th, while 24 states held primary elections, 87 tornadoes occurred. This deadly event, nicknamed the "Super Tuesday Outbreak", caused 57 deaths in the southeastern U.S. for a total of 58 nationally in the month of February. The number of tornado related fatalities reported in February was the second highest on record for the month.

May was also an active month with 460 confirmed tornadoes, making it the third most active May on record. For the period January through May, a total of 112 tornado fatalities were reported. This year shares the record with 1968 as the eighth deadliest January through May period since reliable records began in 1953. Severe weather continued into June when two outbreaks spawned 289 confirmed tornadoes.

More information on severe weather can also be found on NCDC's Hazards page.

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Hurricanes & Tropical Storms

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.


Atlantic Basin

Averages:

The 2008 Atlantic basin hurricane season was above the 1950-2000 average with 16 named storms, of which eight were hurricanes, including five major hurricanes. The ACE index of hurricane activity indicated an above-average season, with a preliminary value of approximately 142 x104 knots2. In terms of accumulated cyclone energy (based on integrated wind power of all tropical cyclones during the season, both landfalling and those remaining out at sea), 2008 ranked as the 16th most energetic season out of the last 59.

NOAA's ACE Index 1949-2008
Atlantic ACE Image
Click for larger image Atlantic ACE

2008 Season Summary:

The first 2008 Atlantic storm to make landfall in the U.S. was Hurricane Dolly. The storm made landfall in South Padre Island, Texas on July 23rd. While there were no direct deaths from the hurricane, it caused an estimated $1.2 billion of damage. Tropical Storm Fay was the first storm in recorded history to make landfall four times in a single state. Fay first made landfall in southern Florida on August 18th and continued to batter Florida through the 21st. Thirty-six deaths were blamed on the tropical storm and damages are estimated in excees of $180 million.

On August 25th, Hurricane Gustav formed in the South Caribbean as the season's second major hurricane. Hurricane Bertha on July 3rd was the season's first. Hurricane Gustav first made landfall in Haiti and again in Western Cuba. On September 1st, Gustav made U.S. landfall in Louisiana as a category 2 hurricane. Gustav was blamed for 138 deaths in the U.S. and the Caribbean and an resulted in an estimated $4.3 billion of damage in the U.S.

As Gustav made landfall, Hurricane Ike began to form in the eastern Atlantic. Facilitated by favorable atmospheric conditions, Ike was able to quickly intensify into a category 4 hurricane on September 4th. On the 7th, while trying to recover from three earlier storms (Fay, Gustav, and Hanna), Cuba was hit again with winds estimated at 127-132 mph (203-213 km/h or 110-115 knots). Ike made U.S. landfall at Galveston, Texas, on September 13th as a category 2 hurricane. One-hundred-sixty-four deaths were blamed on Ike and damage estimates totaled more than $30 billion in the U.S., Cuba, and Bahamas, making Ike the 3rd costliest hurricane of all time behind Andrew and Katrina.

Hurricane Paloma was the last major hurricane in the Atlantic Basin's 2008 season. It was also the third major hurricane to hit Cuba (Gustav and Ike). This marks the first time on record that Cuba has been struck by three major hurricanes in one season. Paloma made landfall in Santa Cruz del Sur, Cuba on November 8th and caused an estimated $1.4 billion of damage.

This year was the second most destructive hurricane season on record with up to $54 billion in damage (2008 USD). The most destructive was $128 billion reported in 2005. It was the only year on record in which a major hurricane existed in every month from July through November in the North Atlantic (Bertha, Gustav, Ike, Omar, and Paloma). On July 20th, there were three active storms: Hurricane Bertha, and Tropical Storms Cristobal and Dolly. This was the earliest known date for three storms to be active on the same day. It is also noteworthy that none of the five major hurricanes (category 3 and above) were of major status at the time of U.S. landfall. This information is based on preliminary data and is subject to change. More details about all the 2008 Atlantic tropical systems can be found below.


Pacific Basin

Averages:

The 2008 East Pacific basin hurricane season was near the 1950-2000 average with 18 named storms, of which seven were hurricanes, including two major hurricanes. The ACE index of hurricane activity indicated an below-average season, with a preliminary value of approximately 83 x104 knots2. In terms of accumulated cyclone energy (based on integrated wind power of all tropical cyclones during the season, both landfalling and those remaining out at sea), 2008 was below normal.

NOAA's ACE Index 1970-2008
Pacific ACE Image
Click for larger image Pacific ACE

2008 Season Summary:

Eighteen named storms formed in the East Pacific Hurricane Basin during 2008, which is near the 50-year average. Seven of these storms were classified as hurricanes and two of these were major hurricanes (Category 3-5 on the Saffir-Simpson Scale). The most notable storm of the season was Norbert, which became a Category 4 hurricane on October 8. Norbert made landfall on the western side of the Baja Peninsula on the next day as a category 2. The storm then made another landfall in Mexico as a category 1, killing 8 people.

Another notable storm in the East Pacific was Tropical Storm Alma. Alma made landfall on the northwestern coast of Nicaragua near León killing nine people. Damage from Alma is estimated at $33 million.


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.

July 2008 PHDI

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The data presented in this drought report are preliminary. Ranks, anomalies, and percent areas may change as more complete data are received and processed.

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National Drought Overview

Dry conditions occurred during much of the year across large parts of the Southeast, West, northwestern Great Lakes, and south central Texas. Most months (February-December) had severe dryness over one or more of these areas. The year was dominated by weather patterns which brought large areas of wetness to the central and northeastern areas of the country, especially from February through October and December, with other areas missing the precipitation. The December 30 U.S. Drought Monitor map depicts conditions at the end of 2008.

Several short-lived dry episodes occurred in other regions throughout the year, notably along the mid-Atlantic coast states in January and August (Delaware had its driest August on record), the Gulf Coast states in March and July, the eastern Great Lakes in April, New England and Florida in May, the Ohio Valley in August and September, and parts of the northern Plains in March, April, July, and August. The percent area* of the contiguous U.S. experiencing moderate to extreme drought expanded and contracted several times during the year, starting at about 27 percent at the beginning of January, reaching a peak of about 31 percent in June, and declining to about 21 percent by the end of December. According to U.S. Drought Monitor statistics, the percent of the U.S. (including Alaska, Hawaii, and Puerto Rico) experiencing moderate (D1) to exceptional (D4) drought was about 29 percent at the beginning of the year, peaked at 30 percent in mid-January, then generally declined throughout the year to about 16 percent by December 30 (after a slight surge during the summer).

*This drought statistic is based on the Palmer Drought Index, a widely used measure of drought. The Palmer Drought Index uses numerical values derived from weather and climate data to classify moisture conditions throughout the contiguous United States and includes drought categories on a scale from mild to moderate, severe and extreme.

The most extensive national drought coverage during the past 110 years (the period of widespread reliable instrumental records) occurred in July 1934 when 80 percent of the contiguous U.S. was in moderate to extreme drought. Although the current drought and others of the 20th century have been widespread and of lengthy duration, tree ring records indicate that the severity of these droughts was likely surpassed by other droughts including that of the 1570s and 1580s over much of the western U.S. and northern Mexico.

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Regional Drought Overview

The very dry conditions of 2007 continued into 2008 in some areas. Similar to last year, impacts from drought in 2008 were felt largely by the agricultural and hydrological communities. Low streams, reservoirs and stock ponds, and depleted soil moisture ravaged pastures, range land, and cropland as the growing season progressed. Nationally, short to very short (i.e., dry to very dry) topsoil moisture conditions reached a peak area at the end of July, with August showing recovery in some areas but worsening conditions in others. As the year progressed, the percent area of the nation with below to much below normal streamflows generally decreased, but increased again later in the year.

12-Month Standardized Precipitation Index, January-December 2008
24-Month Standardized Precipitation Index, January 2007-December 2008

Conditions in the Southeast U.S. were especially dry. The year started with low streamflows across much of the region. Voluntary and mandatory water restrictions continued in many communities. April 2007-March 2008 was the driest April-March on record for North Carolina, prompting then-Governor Easley to ask local officials to continue their aggressive water conservation efforts. Beneficial April rains improved conditions slightly, but dry weather returned in the summer.

USGS average streamflow for July 2008

USGS streamflow for July 2008. Brown shades are below-average streamflow, blue shades are above-average streamflow.

By the end of June, more than half of the topsoil in several southeastern states was in dry to very dry condition, and pasture and range land was in poor to very poor condition across one-third of North Carolina, 44 percent of Georgia, and two-thirds of South Carolina. Upstate South Carolina (climate division 2) experienced the driest August-July in its 115-year record. While its duration was not a record, the intensity of the 2008 drought reached record low levels for Upstate South Carolina, according to the Palmer Drought Index. By October, river levels and well levels in the North Carolina-South Carolina-Georgia border area were at all-time record low levels or approaching these levels. On October 21, Lake Hartwell set a new record for extreme minimum pool elevation when it dropped to 642.385 feet, 18 feet below normal pool level of 660 feet. The lake is located in northeast Georgia along the Georgia-South Carolina border and is one of the Southeast's largest and most popular public recreation lakes. Built by the U.S. Army Corps of Engineers between 1955 and 1963 as part of a flood control, hydropower, and navigation project, authorized purposes now include recreation, water quality, water supply, and fish and wildlife management. According to media reports (AP 10/19), communities in the Southeast continued to struggle in the face of the lingering drought:

  • Some communities faced water restrictions.
  • Burning bans and warnings were common in the Virginias.
  • Tennessee Governor Phil Bredesen requested a federal designation of agricultural disaster for 39 counties because of crop and livestock losses.

Persistent dryness spread into the Ohio Valley and Great Lakes by August. Topsoil was dry to very dry across 70 to 80 percent of Kentucky, Indiana, Ohio, Michigan, and Wisconsin, with half of the pastures and range land of Kentucky and Michigan, and nearly half in Ohio, in poor to very poor condition. By the end of September, the percentages had reached 93 percent (for topsoil) and 77 percent (for pastures and range land) in Kentucky, which had the second driest August-September on record.

Three main areas of the Great Plains suffered from drought in 2008: the northern Plains, south central Texas, and the area where the Oklahoma panhandle touches Colorado, New Mexico, and Texas.

The cold half-year (October-March) is the dry season in the northern Plains. Nevertheless, the 2007-2008 winter was much drier than normal for much of the area, with North Dakota experiencing the driest December-March and November-March in its 114-year record. Minnesota had the second driest November-March. The dryness continued into the spring, although not as severe, with North Dakota experiencing its 13th driest March-May. By the end of May, 55 percent of the state had topsoil in the dry to very dry categories and 52 percent of the pasture and range land was in poor or very poor condition. Drought was most severe in the western part of the state. Pasture and range land remained ravaged even as late as the beginning of fall.

The precipitation gradient was very sharp across the Oklahoma panhandle, with some precipitation falling over the eastern sections but mostly missing the western portions during the first six months of 2008. The Colorado State Climatologist's office reported a significant number of dust storms during the spring in southeast Colorado. By June, drought was having some severe localized impacts in the Oklahoma panhandle. According to media reports (The Oklahoman, 6/13), impacts included large-scale livestock sell-offs, wildfires, and growing risk of significant dust storms. In Cimarron County, Oklahoma, the wheat crop was nonexistent this year, pastures were dormant or dead, and wind erosion of the soil was occurring -- according to old-timers in the area -- like back in the Dust Bowl days. Governor Henry requested federal disaster aid in June for Oklahoma farmers and ranchers who were hit by drought and extreme weather conditions in nine northwest counties. Exceptional drought conditions developed in the area by the end of the month, according to the July 1 U.S. Drought Monitor map. Beneficial rains over the area beginning in July improved conditions during the summer.

Conditions were dry in the southern Plains states at the beginning of 2008. According to the USDA, end-of-January state reports indicated that the winter wheat crop was suffering, with 61 percent of the crop in poor to very poor condition in Texas, 30 percent in Oklahoma, and 25 percent in Kansas. NOAA observations noted that, at the beginning of February, Lake Meredith in the Texas Panhandle reached a record low level at 50.15 feet. At 48 feet, portable pumps must be brought in to get water from the lake as the lake level will be below the permanent pumps. Lake Meredith is a major supplier of water to the Texas Panhandle. By March 30, 47 percent of the winter wheat crop in Texas, 32 percent in Colorado, 21 percent in Oklahoma, and 20 percent in Kansas was rated poor to very poor. By the end of June, over 70 percent of the topsoil in Texas and New Mexico was rated dry to very dry. The January-June 2008 precipitation pattern showed the driest areas over south central and western Texas.

Southern Texas (climate division 9) experienced the driest October-June in its 114-year record. According to media reports, Texas agricultural specialists feared record losses in agriculture during 2008 due to heat and drought conditions combined with skyrocketing input costs. Cotton producers in southern Texas had already lost nearly their entire crop. By the end of October, 57 percent of the topsoil moisture in Texas was still short to very short. As reported by local media, the flow at Jacob's Well, a natural spring in Hays County in central Texas, stopped in September for only the second time in its recorded history. The Wimberley Valley Watershed Association's David Baker said, "In the summer of 2000 it did stop for the first time that we know of in modern times ... and in all accounts that we know of. It did flow through the drought of the 50's." The well is fed by the Trinity Aquifer, which is the primary water supply for Wimberley and much of the Hill Country. Very dry conditions during November and December ended the year, with Texas having the fourth driest December statewide. By mid-December, many streams and rivers in central Texas were below 10 percent of normal flow, causing reservoir levels to continue to fall. Precipitation in San Antonio during the 15-month period through November (September 2007-November 2008) was the lowest in any similar period since recordkeeping began in 1871. USDA crop reports at the end of the year revealed poor to very poor conditions for 74 percent of Texas oats and 46 percent of wheat. Yields were generally low (with a few areas of good yields) for the Texas cotton, sorghum, and pecan harvests.

U.S. Drought Monitor, July 1, 2008

Statewide Precipitation Ranks, October 2007-September 2008

In the three climatological regions of the western U.S. -- the West, Northwest, and Southwest regions -- the 2007-2008 winter began with above-normal precipitation, which laid down an above-normal mountain snowpack. There was hope that the spring snowmelt would fill reservoirs which were largely below normal, but the precipitation pattern shifted in March with drier weather predominating for the next several months. This resulted in a drier-than-normal hydrological year (October-September) for many western states, in spite of the wet start to the winter. Beneficial rain and snow fell over parts of the West during November and December. But, by the end of 2008, reservoirs were still below normal for several western states.

For California, October 2007-September 2008 was the second consecutive dry hydrological year. The persistent dryness in 2007 had depleted soil moisture, ravaged pastures, and dried up streams, wells, and springs. Voluntary and mandatory water restrictions were in place in many communities in California at the beginning of 2008. As the pattern starting in March 2008 exacerbated conditions, the dryness was so severe that Governor Schwarzenegger declared the first statewide drought since 1991. Numerous lightning-sparked wildfires were burning across the state by the end of June, with 97 percent of the state's pasture and range land in poor to very poor condition. By the beginning of September, this value had reached 100 percent for California and 52 percent for Oregon. Irrigated crops were thriving, but dryland agriculture was suffering.

Vegetation Drought Response Index, 9/22/2008

By late summer and early autumn, soils in the Pacific Northwest states continued to dry, with topsoil moisture reaching more than 50 percent short to very short for Idaho, Oregon, and Washington. Natural vegetation was significantly stressed across much of the West. Soil moisture conditions remained dry in some areas at the end of December.

March-October 2008 was the driest such 8-month period on record for California and Nevada. California also had the driest February-September, February-November, and March-June on record. As October came to a close, the California Department of Water Resources (www.water.ca.gov/drought) called the drought of the past two years, "the most significant water crisis in California's history." The drought was also arguably the biggest factor in the wildfires that made this year's "the worst fire season in California's history," according to Governor Schwarzenegger and CalFire. Water supply problems in the months ahead were expected. As noted by the North County Times (10/20), the amount of water being stored in California reservoirs was at its lowest point in 14 years, underscoring the severity of a worsening drought that could prompt providers to order rationing in San Diego and Riverside counties as early as January 2009. According to news reports (San Francisco Chronicle, 10/30), California announced that it planned to cut water deliveries to their second-lowest level ever in 2009, raising the prospect of rationing for cities and less planting by farmers. The Department of Water Resources projected that it would deliver just 15 percent of the amount that local water agencies throughout California request every year. The reservoirs that are most crucial to the state's water delivery system were at their lowest levels since 1977, after two years of dry weather and court-ordered restrictions on water pumping out of the Sacramento-San Joaquin Delta.

9/30/08 U.S. Drought Monitor map

Persistently dry weather during much of 2008 in Hawaii resulted in severely reduced streamflows by spring. Continued dryness resulted in poor pasture, range land, and irrigation reservoir conditions, prompting the introduction of extreme drought to the islands during the summer. Through July 22, year-to-date rainfall totals stood at just 2.86 inches (30 percent of normal) in Honolulu, Oahu; 2.98 inches (26 percent) in Kahului, Maui; and 8.22 inches (40 percent) in Lihue, Kauai. On the Big Island, Hilo's January 1-July 22 rainfall totaled 74.66 inches (109 percent of normal), although more than half (39.08 inches) of that amount fell during the first half of February. According to agricultural reports from the USDA, drought on parts of the Big Island dried up stock water ponds normally supplied by runoff. On Oahu, a mandatory 30 percent reduction in water use was issued for the Waimanalo irrigation system users. Sugar planting was suspended in July on central Maui. On the island of Oahu, deteriorating conditions led to additional requests for voluntary reductions in public water consumption. Widespread beneficial rains fell in December, but significant drought continued over Moloka'i, Maui, and the Big Island at the end of the year.

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Pre-instrumental Drought Perspective

Tree ring records provide a useful paleoclimatic index that extends our historical perspective of droughts centuries beyond the approximately 100-year instrumental record. Several paleoclimatic studies have shown that droughts as severe or worse, both in magnitude and duration, than the major 20th century droughts have occurred in the U.S. during the last thousand years. The following paleodrought report was prepared by the NOAA/NCDC Paleoclimatology and Climate Monitoring branches during 2008:

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Global Snow & Ice

Sea Ice Extent

According to the National Snow and Ice Data Center, the September Northern Hemisphere average sea ice extent, which is measured from passive microwave instruments onboard NOAA satellites, was 4.67 million square kilometers (34 percent below the 1979-2000 mean), the second lowest on record behind 2007. The Northern Hemisphere sea ice extent time series to the right depicts the decrease of the sea ice extent from June-September. It is seen that from May to June, the sea ice extent was similar to 2005 and 2007. However, by early August, the 2008 sea ice extent surpassed the 2005 extent but was nearly nine percent above the 2007 record. The lowest Northern Hemisphere sea ice extent in the seasonal cycle occurs in September each year. The average September rate of sea ice decline is 11.7 percent per decade. A complete summary of the 2008 Northern Hemisphere sea ice extent is available, courtesy of the National Snow and Ice Data Center.

In contrast, the 2008 Southern Hemisphere sea ice extent saw several monthly records when it was the largest sea ice extent for January, March, and April 2008. It also was the second largest sea ice extent for February (behind 2003) and June (behind 1979), and third largest May (behind 2000 and 1996).

For further information on Northern and Southern Hemisphere snow and ice conditions, please see the NSIDC News page, provided by the NOAA's National Snow and Ice Data Center (NSIDC).

Arctic sea ice conditions are inherently variable from year to year in response to wind, temperature and oceanic forcings. Quite often a "low" ice year is followed by recovery the next year. But increasing surface temperatures in high latitudes have contributed to progressively more summer melt and less ice growth in the fall and winter. While natural variability is responsible for year-to-year variations in sea ice extent, three extreme minimum extent years along with evidence of thinning of the ice pack suggest that the sea ice system is experiencing changes that may not be solely related to natural variability.

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Northern Hemisphere Snow Cover Extent

As shown in the time series to the right, the mean Northern Hemisphere snow cover extent during the boreal winter (December 2007-February 2008) was above average. This can be primarily attributed to the multiple snow and ice storms that affected much of the Northern Hemisphere during the winter. This resulted in the fourth largest snow cover extent on record. The mean Northern Hemisphere winter snow cover extent for the 1967-2008 period of record is 45.5 million square kilometers.

Across North America, snow cover for winter 2007/2008 was above average, the sixth largest extent since satellite records began in 1967. A series of snow and ice storms struck the U.S. throughout the winter. The heavy snowfall during the winter prompted more than 4,700 new daily snowfall records and several new seasonal records across the contiguous U.S. The mean North America winter snow cover extent for the 1967-2008 period of record is 17.1 million square kilometers.

Mean Northern Hemisphere snow cover extent during spring 2008 was below average, resulting in the third least snow cover extent on record, behind 1968 and 1990. Much of this was due to anomalously warm conditions across Asia, Europe, and parts of Alaska and Canada during the boreal spring (March-May). The mean Northern Hemisphere spring snow cover extent for the 1967-2008 period of record is 30.8 million square kilometers.

Snow cover for boreal spring 2008 across North America was slightly above average, due to a series of snow storms that struck the U.S. early in the season. This resulted in the 14th largest extent since satellite records began in 1967. The mean North American spring snow cover extent for the 1967-2008 period of record is 12.9 million square kilometers.

Data were provided by the Global Snow Laboratory, Rutgers University.

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Upper Air

During the past century, global surface temperatures have increased at a rate near 0.05°C/decade (0.09°F/decade), but this trend has increased to a rate of approximately 0.16°C/decade (0.29°F/decade) during the past 30 years. There have been two sustained periods of warming, one beginning around 1910 and ending around 1945, and the most recent beginning about 1976. Temperatures during the latter period of warming have increased at a rate comparable to the rates of warming projected to occur during the next century with continued increases of anthropogenic greenhouse gases.

Temperature measurements have also been made above the Earth's surface over the past 51 years using balloon-borne instruments (radiosondes) and for the past 30 years using satellites. These measurements support the analyses of trends and variability in the troposphere (surface to 10-16 km) and stratosphere (10-50 km above the earth's surface).

The best source of upper air in-situ measurements for studying global temperature trends above the surface is the Radiosonde Atmospheric Temperature Products for Assessing Climate (RATPAC) dataset.

Data collected and averaged between the 850-300 mb levels (approximately 5,000 to 30,000 feet above the surface) indicate that 1958-2008 global temperature trends in the middle troposphere are similar to trends in surface temperature; 0.13°C/decade (0.23°F/decade) for surface and 0.16°C/decade (0.29°F/decade) for mid-troposphere. Since 1976, mid-troposphere temperatures have increased at a rate of 0.17°C/decade (0.31°F/decade). For the January-December 2008 period, global mid-troposphere temperatures were 0.13°C (0.23°F) above the 1971-2000 mean and the 17th warmest.

Since 1979, NOAA's polar orbiting satellite measurements have also been used to measure temperatures in the troposphere and stratosphere. Microwave Sounding Unit (MSU) data are analyzed for NOAA by the University of Alabama in Huntsville (UAH), Remote Sensing Systems (RSS, Santa Rosa, California) and the University of Washington (UW). These observations show that the global average temperature in the middle troposphere (the layer which is centered at an altitude of 2 to 6 miles, but which includes the lower stratosphere) has increased, though differing analysis techniques have yielded similar but different trends (see below).

In all cases these trends are positive. The analysis performed by RSS reveals a trend of 0.09°C/decade (0.17°F/decade) while the UAH analysis reveals a lower trend of 0.04°C/decade (0.08°F/decade). When adjusted by University of Washington scientists to remove the stratospheric influences from the RSS and UAH mid-troposphere average, the trends increase to 0.15°C/decade (0.28°F/decade) and 0.11°C/decade (0.20°F/decade), respectively. (A journal article is available that describes the University of Washington adjustments to remove the stratospheric influence from mid-troposphere averages.) Trends in these MSU time series are similar to the trend in global surface temperatures, which increased at a rate near 0.16°C/decade (0.29°F/decade) during the same 30-year period.

The MSU anomalies for the January-December period were the coolest since 2000, breaking the streak of consecutive warmer-than-average temperatures.

While middle tropospheric temperatures reveal an increasing trend over the last three decades, stratospheric temperatures (14 to 22 km / 9 to 14 miles above the surface) have been below average since the warming effects from the 1991 Mt. Pinatubo eruption dissipated in 1993. January - December 2008 was the 16th consecutive year with below-average temperatures (an anomaly of -0.62°C/-1.12°F), the second coolest year behind 1996 which had an anomaly of -0.64°C/-1.15°F. The below-average stratospheric temperatures are consistent with the depletion of ozone in the lower stratosphere and the effects of increasing greenhouse gas concentrations. The large temperature increase in 1982 is attributed to the volcanic eruption of El Chichon, and the increase in 1991 was associated with the eruption of Mt. Pinatubo in the Philippines.

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References

Christy, John R., R.W. Spencer, and W.D. Braswell, 2000: MSU tropospheric Temperatures: Dataset Construction and Radiosonde Comparisons. J. of Atmos. and Oceanic Technology, 17, 1153-1170.

Free, M., D.J. Seidel, J.K. Angell, J. Lanzante, I. Durre and T.C. Peterson (2005) Radiosonde Atmospheric Temperature Products for Assessing Climate (RATPAC): A new dataset of large-area anomaly time series, J. Geophys. Res., 10.1029/2005JD006169.

Free, M., J.K. Angell, I. Durre, J. Lanzante, T.C. Peterson and D.J. Seidel(2004), Using first differences to reduce inhomogeneity in radiosonde temperature datasets, J. Climate, 21, 4171-4179.

Fu, Q., C.M. Johanson, S.G. Warren, and D.J. Seidel, 2004: Contribution of stratospheric cooling to satellite-inferred tropospheric temperature trends. Nature, 429, 55-58.

Lanzante, J.R., S.A. Klein, and D.J. Seidel (2003a), Temporal homogenization of monthly radiosonde temperature data. Part I: Methodology, J. Climate, 16, 224-240.

Lanzante, J.R., S.A. Klein, and D.J. Seidel (2003b), Temporal homogenization of monthly radiosonde temperature data. Part II: trends, sensitivities, and MSU comparison, J. Climate, 16, 241 262.

Mears, Carl A., M.C. Schabel, F.J. Wentz, 2003: A Reanalysis of the MSU Channel 2 tropospheric Temperature Record. J. Clim, 16, 3650-3664.

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Wildfires

As 2008 came to a close, reports of new large fires dwindled across the nation. This marks the end of a relatively mild fire season for the United States as a whole, as compared to the previous years of 2007 and 2006. However, some areas of the nation experienced significant and costly fire activity in 2008. Severe to exceptional dryness occurred across many parts of the United States throughout much of the season, according to the U.S. Drought Monitor. Drought conditions and high fire risk were particularly persistent in areas of the Northwest and Southeast.

Fire activity was primarily clustered in the western and southeastern regions of the nation in 2008, declining to small areas of activity in the central U.S. by the end of November. Across the nation, the majority of fire activity occurred during the months of July and August. California suffered severe fires throughout the year, driven by high temperatures, dry conditions, and strong Santa Ana winds. Mid–November fires ravaged much of Southern California, resulting in the destruction of hundreds of dwellings.

Following the highly destructive wildfire seasons of 2006 and 2007, 2008 started off on the same track, with fewer fires, but more acreage burnt than average. Ample June precipitation accompanied a marked decline in acreage burned, dropping 2008 to levels below those of recent years. From July to November, a greater number of fires were reported, when compared to the 1985–2008 average, but with less acreage burnt. July and August were particularly active, with no fewer than 34 large fires burning across the nation at the end of July. Tragically, the 2008 wildfire season claimed the lives of 21 firefighters, according to news reports, including nine who died in a helicopter crash in Northern California in early August.

By year's end, only small areas in Texas, Hawai'i, California, and the Southeast U.S. were reporting extreme to exceptional drought. Fire danger also dropped to moderate levels across most of the U.S., except for portions of California, Texas, Kansas, and Nebraska, where risk remained high. This is a marked improvement over drought conditions present at mid-summer, when much of the Southeast, South, northern Great Plains, the West, and Hawai'i was in moderate to exceptional drought and fire danger was high to extreme over most of the western United States.

End of Year Fire Danger Maps:

January 01, 2009 Fuel Moisture Maps:

Annual Wildfire Statistics

(Source: NIFC)
Annual Totals Nationwide Number of Fires Nationwide Number of Acres Burned
2008 77,772 5,159,907
2007 85,705 9,328,045
2006 96,385 9,873,745
2005 66,753 8,689,389
2004 65,461 8,097,880
2003 63,629 3,960,842
2002 73,457 7,184,712
2001 84,079 3,570,911
2000 92,250 7,393,493
1999 92,487 5,626,093
1998 81,043 1,329,704
1997 66,196 2,856,959
1996 96,363 6,065,998
1995 82,234 1,840,546
1994 79,107 4,073,579
1993 58,810 1,797,574
1992 87,394 2,069,929
1991 75,754 2,953,578
1990 66,481 4,621,621
1989 48,949 1,827,310
1988 72,750 5,009,290
1987 71,300 2,447,296
1986 85,907 2,719,162
1985 82,591 2,896,147
Average
(1985 – 2008)
77,202 4,641,405

For the year as a whole, nearly 80,000 wildland fires burned more than 5 million acres (2 million hectares), according to preliminary year–end statistics from the National Interagency Fire Center (NIFC). These values rank 2008 near average in terms of the number of fires and above average for acreage burnt. The 2008 fire season's estimated 77,772 wildfires were 570 fires more than the 1985–2008 average of 77,202 fires. Acreage burnt in 2008 was approximately 518,502 acres (209,831 hectares) more than the 1985–2008 average of 4,641,405 acres (1,878,317 hectares), ranking 2008 as the ninth most acreage burnt since 1985, when NCDC considers reliable records to have become available. The quantity of acreage burnt in 2008 was close to 4 million fewer acres (1.62 million hectares) than either of the previous years of 2007 and 2006. Since the mid–1980s, the total number of acres burnt has gradually increased, though 2008 levels show a reduction to quantities lower than the four previous years. The number of wildfires reported by NIFC during that same period does not show a significant linear trend.

The wildfire season in the U.S. generally extends from March 1st through November 30th. The 2009 wildfire summary page will resume coverage in early April unless fire conditions in 2009 warrant an earlier start.

(Dashed lines on the above charts are OLS linear trends fit to the data.)


El Niño/Southern Oscillation

2008 Annual Report


Oceanic Conditions:

The El Niño/Southern Oscillation (ENSO) began 2008 in a cold phase (i.e., La Niña) which developed during September of 2007, peaked in February 2008, began to dissipate in March, and completely disolved by June. During the first half of 2008, below average sea-surface temperature (SST) anomalies were observed in the central and eastern equatorial Pacific Ocean, with the coldest SST anomalies measured in February in the Niño 3.4 region. By June 2008, the near-equatorial SST anomalies had warmed to near-normal in the central Pacific region as the ENSO transitioned to a neutral phase.

In the western equatorial Pacific, SSTs returned to near-average temperatures by July, remaining near average through November. This can be seen in the monthly averaged SST anomalies in the Niño 4 region. Cooling in the upper-ocean along the equatorial Pacific in the latter part of 2008 did give some indication of the possible late onset of an ENSO cold event. However, neutral ENSO conditions remained at the end of the year, with below-average SSTs.

A slight cooling began in late October when colder SST anomalies developed along the equatorial zone due to stronger than average trade-wind flow, which enhanced upwelling and decreased SST anomalies in both the eastern and central tropical Pacific.

Atmospheric Conditions:

The Southern Oscillation Index (SOI) was positive for the entirety of 2008, save the month of May when it was only slightly negative. The stronger positive numbers in the first part of the year reflect the conditions during the La Niña. Prolonged periods of positive SOI values coincide with abnormally cold ocean waters across the eastern tropical Pacific typical of La Niña episodes.

At the beginning of 2008, the Outgoing Longwave Radiation (OLR) Index was strongly positive as tropical convection was suppressed across the equatorial Pacific in response to the cold SSTs that had developed in association with the La Niña present at that time. Outgoing Longwave Radiation values have been positive since January 2007 when there was a warm phase (i.e., El Niño) present.


Citing This Report

NOAA National Climatic Data Center, State of the Climate for Annual 2008, published online December 2008, retrieved on December 18, 2014 from http://www.ncdc.noaa.gov/sotc/2008/13.