Drought - July 2016


NCEI added Alaska climate divisions to its nClimDiv dataset on Friday, March 6, 2015, coincident with the release of the February 2015 monthly monitoring report. For more information on this data, please visit the Alaska Climate Divisions FAQ.

Issued 11 August 2016
Contents Of This Report:
Map showing Palmer Z Index
Percent Area of U.S. in Moderate to Extreme Drought, Jan 1996 to present
West region temperatures, August-July, 1895-2016

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


The U.S. Drought Monitor drought map valid August 2, 2016
The U.S. Drought Monitor drought map valid August 2, 2016.

During July 2016, the weather over the CONUS was dominated by a longwave ridge over the southern tier States, with the storm track keeping along the Canadian border. Fronts and low pressure systems moved along the jet stream flow, with fronts occasionally stalling out from the Central Plains to Midwest and some dipping into the Southeast. Areas of above-normal precipitation occurred with storm systems moving along the storm track from the Northwest to Northern Plains, and from the Central Plains to Ohio Valley. The rain, clouds, and fronts kept monthly temperatures generally cooler than normal in these areas. Beneath the subtropical high pressure ridge, the weather was generally warmer and drier than normal, especially across much of the West, Southern Plains, Southeast, and Northeast. Ridges and troughs passing over Alaska gave the state a mixed temperature and precipitation anomaly pattern. July was generally warmer than normal across most of the state, drier than normal in the north and parts of the panhandle, and wetter than normal over much of the rest of the state. Heavy rains at the beginning of the month and Tropical Storm Darby rains at the end of the month gave Hawaii a wetter than normal month. Much of Puerto Rico was also wetter than normal. Drought and abnormal dryness expanded in parts of the country and contracted in other, sometimes nearby, areas. Contraction dominated Hawaii, but for the nation as a whole, drought expanded more than it shrank, with the national drought footprint increasing to 17.7 percent of the U.S. (21.1 percent of the CONUS). When integrated across the CONUS, July 2016 ranked as the 52nd wettest July in the 1895-2016 record. According to the Palmer Drought Index, which goes back to the beginning of the 20th century, about 22.0 percent of the CONUS was in moderate to extreme drought at the end of July, an increase of about 7 percent compared to last month.

Percent area of the CONUS in moderate to exceptional drought, January 4, 2000 to present, based on the U.S. Drought Monitor
Percent area of the CONUS in moderate to exceptional drought, January 4, 2000 to present, based on the U.S. Drought Monitor.


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. While both the PDSI and PHDI indices show long-term moisture conditions, the PDSI depicts meteorological drought while the PHDI depicts hydrological drought. The PDSI map shows less severe and extensive drought in parts of the West than the PHDI map because the meteorological conditions that produce drought and wet spell conditions are not as long-lasting as the hydrological impacts.

Palmer Z Index map Palmer Hydrological Drought Index map

Used together, the Palmer Z Index and PHDI maps show that short-term dry conditions occurred across parts of the Northeast, Ohio, and Southern Plains, and much of the Southeast, Southwest, and Central to Southern Rockies. This short-term dryness expanded or initiated long-term dry conditions in July compared to June in most of these areas. Short-term wet conditions expanded or intensified long-term wet conditions in parts of the Upper Midwest to Ohio Valley, and eliminated long-term drought conditions in parts of the Northern Plains.



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

6-month Standardized Precipitation Index

The SPI maps illustrate how moisture conditions have varied considerably through time and space over the last two years. Dryness dominates much of the Northeast at all time scales, with the dryness stretching into Ohio at the 1 to 3 month time scales. The Southeast has had dry conditions at the 1 to 6 month time scales, but near normal to wet conditions at the longer time scales. Dryness is evident in parts of the Southwest at the 1 to 9 month time scales, and in parts of California at all time scales. Dry conditions dominate the Southern to Central Rockies at the 1 to 3 month time scales, especially the area around Wyoming and adjacent Nebraska, South Dakota, and Montana. Parts of this area has dryness at the 6 to 12 month time scales, but near normal to wet conditions overtake the dryness at the 24-month time scale. Parts of the Southern Plains (mainly Texas) are dry at the 1-month time scale, with massive wet conditions evident at the 3 to 24 month time scales, especially at the longer time scales. In parts of the Northern Plains, July was wet but the 2 to 3 month time scales (May-July) have areas of dryness, with wet conditions dominating at the longer time scales. Much of the Mississippi and Ohio Valleys is wet at most time scales, with wetness dominating most of the country at the 9 to 24 month time scales.


9-month Standardized Precipitation Index 12-month Standardized Precipitation Index 24-month Standardized Precipitation Index



Standardized Precipitation Evapotranspiration Index


The SPI measures water supply (precipitation), while the SPEI (Standardized Precipitation Evapotranspiration Index) measures the combination of water supply (precipitation) and water demand (evapotranspiration as computed from temperature). Warmer temperatures tend to increase evapotranspiration, which generally makes droughts more intense.

1-month SPEI for current month
1-month SPEI for current month.
1-month SPI for current month
1-month SPI for current month.

Temperatures were much warmer than normal across the southern and eastern States during July. The combination of these unusually warm temperatures and the lack of precipitation resulted in the 1-month SPEI map showing more severe drought conditions than the 1-month SPI map, especially in the Southwest to Southern Plains. When the heat and dryness of the last two months is examined, the 2-month (June-July) SPEI map shows even more severe drought conditions than the SPI map in the West. Warmer temperature anomalies for the last six months across the country contributed to more severe drought on the 6-month SPEI map compared to the SPI map, especially in the West where precipitation was below normal. Widespread warm temperature anomalies for the last 12 months resulted in more severe drought in the areas with below-normal precipitation on the August 2015-July 2016 SPEI map compared to the SPI map, and also resulted in less extreme wetness where above-normal precipitation fell.

August-July temperatures for western U.S., 1895-2016

Significant differences between the SPEI and SPI maps begin to appear in the West at the 24-month time frame (SPEI vs. SPI) and become increasingly significant at the 36-month (SPEI vs. SPI), 48-month (SPEI vs. SPI), 60-month (SPEI vs. SPI), and even 72-month (SPEI vs. SPI) time scales. This is due to persistent above-normal temperatures in the West for the last several years which have increased evapotranspiration and exacerbated drought conditions.


36-month SPEI map 48-month SPEI map 60-month SPEI map

This is especially the case in California, where the last four August-July 12-month periods ranked in the top five warmest such periods for the state in the 1895-2016 record. The last four years cap a period of persistent unusual warmth which has lasted over three decades. The precipitation for the last 12 months gave California a statewide precipitation rank of 52nd wettest (70th driest) for August 2015-July 2016. But the persistent dryness since 2000 still gave the state the driest SPI for the last 60 months and a top-ten dry SPI for the last 48 and 72 months. When the temperature is factored in, California has had the most severe SPEI for the last 60 and 72 months, second most severe SPEI for the last 48 months, and third most severe SPEI for the last 36 months.

California statewide temperature, August-July, 1895-2016
California statewide temperature, August-July, 1895-2016.
California statewide 60-month SPEI for July, 1895-2016
California statewide 60-month SPEI for July, 1895-2016.



Regional Discussion


Monthly streamflow
Monthly streamflow
USDA topsoil moisture short to very short
USDA topsoil moisture short to very short



CONUS Agricultural & Hydrological Impacts:

The dry and hot weather of July increased short-term drought conditions and, for some areas, exacerbated long-term drought. This is reflected in numerous agricultural, hydrological, and other meteorological indicators, both observed and modeled. The dry weather, with increased evapotranspiration, dried soils and stressed vegetation. Where the dry conditions have been continuing for several months, hydrological conditions such as streamflow and groundwater supplies were reduced. On a national scale, as of August 2nd, 18 percent of the nation's cattle inventory, 17 percent of the nation's hay, 12 percent of winter wheat production, 6 percent of corn, and 7 percent of soybean production were in drought. These percentages are all more than the values for the end of June. According to August 1st U.S. Department of Agriculture (USDA) reports, only 6 percent of the nation's corn crop, 7 percent of soybeans, and 8 percent of spring wheat were rated in poor to very poor condition, but 17 percent of the pasture and rangeland were so rated, an increase from the 9 percent at the end of June. And 31 percent of the nation's topsoil moisture and 30 percent of the subsoil moisture were rated short to very short (dry to very dry). The topsoil value is the same as last month, but the subsoil moisture value has increased. On a regional basis, conditions were more extreme.

Drought conditions at the end of the month, as depicted on the August 2nd USDM map, included the following CONUS core drought and abnormally dry areas:



Hawaii: Heavy rains at the beginning of the month combined with Tropical Storm Darby rains at the end of the month to give Hawaii a wetter-than-normal July at most stations. The last 2, 3, and 4 months have generally been wetter than normal. A drier-than-normal pattern is evident at the 7- and 10-month time scales, with more of a mixed pattern of anomalies at 6 months and at the longer time scales (last 12, 24, and 36 months). Moderate to severe drought contracted to cover about 14 percent of the state according to the August 2nd USDM map.

Alaska climate division precipitation ranks for the current month
Alaska climate division precipitation ranks for the current month.

Alaska: July 2016 was wetter than normal across much of Alaska as seen in the low elevation, high elevation SNOTEL, and climate division data sets, with some drier-than-normal areas in the north and extreme south. The last two to three months were wetter than normal across most of the state, and drier than normal in the south, on the station and climate division maps, although the southern dryness was not on the gridded map. Wetness dominated for the last four to six months (station map, climate division map), but was not as extensive for the year to date (station, climate division, gridded maps). Wetter-than-normal conditions dominated for the water year to date (October-July), except in parts of western and northern Alaska. Wet conditions dominated for the last 12 months (station map, climate division map), dryness in the west is evident at the 24-month time scale, and wet conditions again dominate at the 36-month time scale. Like the previous month, some interior stations were cooler than normal during July, but warmer-than-normal temperatures dominated the state. The interior cool anomalies show up well on the 2-month (June-July) station map. But warmer-than-normal temperatures dominated for the last three months (station, gridded, and climate division analyses), six months, seven months (station, gridded maps), ten months, and 12 months. In fact, the climate division maps indicate that most, if not all, of the state had record warm temperatures for the last six, seven, and 12 months. Monthly streamflow was near to above normal at most stations except the extreme southern panhandle. Wildfires developed in Alaska during July, especially during the last half of the month. Abnormal dryness contracted to about 21 percent of the state on the August 2nd USDM map.

Puerto Rico: Puerto Rico was drier-than-normal in the southeast drought area and wetter than normal across the rest of the island during July. This pattern is fairly consistent for the last 2, 3, 6, 7, and 10 months, although the dryness is most widespread at the 3-month time scale. Soils were still dry across parts of central Puerto Rico and the southern coastal area. As shown by the August 2nd USDM map, abnormal dryness and drought continued at about 18 percent of Puerto Rico, with moderate drought at about 6 percent of the island.



CONUS State Precipitation Ranks:

Map showing July 2016 state precipitation ranks Map showing May-July 2016 state precipitation ranks

Georgia statewide precipitation, July, 1895-2016
Georgia statewide precipitation, July, 1895-2016.

July 2016 was drier than normal across much of the West, Southern Plains, and Southeast, and parts of the Northeast. The dryness showed up on the statewide level, with 16 states in the CONUS ranking in their driest third of the 1895-2016 record. Four states had a top ten driest July, including Georgia (second driest July), Florida (third driest), Wyoming (ninth driest), and New Mexico (tenth driest).

The dryness was persistent in the Northeast and Southeast at the 3-month period and still widespread in the West, although localized wet areas masked the statewide ranks. Seventeen states (in the Northeast, Southeast, West, and Northern Plains) ranked in their driest third of the historical record with Massachusetts having the seventh driest May-July.

Map showing January-July 2016 state precipitation ranks Connecticut precipitation, January-July, 1895-2016

The patterns of statewide precipitation ranks for the last six months (February-July) and year to date (January-July) are similar. Dryness is evident in the Northeast, Southeast, and Southwest, and parts of the Northwest, Plains, and Mid-Mississippi Valley. Localized wet areas mask the dryness in some states, with eleven states ranking in their driest third of the historical record for February-July and 13 for January-July, both in the Southwest, Southeast, and Northeast. For the year-to-date, Connecticut had the seventh driest January-July and Massachusetts the ninth driest. In Connecticut, three of the last five year-to-dates have been much drier than average. Wetter-than-normal conditions dominated at the 12-month time scale, with dry conditions in the Northeast and parts of the West. Wyoming and six Northeast states ranked in the driest third of the historical record for August 2015-July 2016, with Connecticut having the sixth driest such 12-month period. The last three August-July periods have been very dry for Connecticut.


Western U.S.


Percent Area of the Western U.S. in Moderate to Extreme Drought, January 1996-present, based on the Palmer Drought Index Percent Area of the Western U.S. in Moderate to Exceptional Drought, January 4, 2000-present, based on the U.S. Drought Monitor

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.

As noted earlier, July was much drier than normal across much of the West, except in the Northwest. The water year-to-date (October 1, 2015-July 31, 2016), overall, has been near to wetter than normal for much of the West. But portions of the northern Rockies and adjacent High Plains in Montana and Wyoming have been persistently dry, with water year-to-date precipitation percentiles in the driest 5 percent. Even though precipitation during this water year has been above normal in many areas, one wet season cannot make up for several years of moisture deficits, so drought continued in both the USDM and Palmer analyses. The dryness of the last two months resulted in expansion of drought on both maps. According to the USDM, 32.2 percent of the West was experiencing moderate to exceptional drought at the end of July, about 4.5 percent more than the previous month. The Palmer Drought Index percent area statistic for the West increased to 40.2 percent.

Agricultural Belts


Primary Corn and Soybean Belt precipitation, July, 1895-2016
Primary Corn and Soybean Belt precipitation, July, 1895-2016.
Primary Corn and Soybean Belt precipitation, March-July, 1895-2016
Primary Corn and Soybean Belt precipitation, March-July, 1895-2016.

July was generally wetter than normal in the Primary Corn and Soybean agricultural belt and warmer than normal in the south but cooler than normal in the north. Regionwide, July 2016 ranked as the sixth wettest and 43rd warmest July in the 1895-2016 record. March serves as the beginning of the growing season. Regionwide, March-July 2016 ranked as the 25th wettest and eighth warmest March-July in the 1895-2016 record.


NOAA Regional Climate Centers:


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


As described by the High Plains Regional Climate Center, the month of July brought a variety of climate conditions to the High Plains region, as some places were wet while others were dry, and temperatures were both cool and warm at times. On the whole, temperatures were closer to average in the High Plains region for the month. The western High Plains experienced warmer and drier conditions, causing streamflows to run low and drought to expand and intensify in western South Dakota/northeastern Wyoming. The dryness in Wyoming was especially pronounced, as a large portion of the state received only 25 percent of normal precipitation for the month, at best. Several locations in Wyoming had a top 5 driest July, including Lander (tied for driest), Rawlins (4th driest), Casper (4th driest), and Laramie (5th driest). Soil moisture declined in July across most of the region except North Dakota, and crop stress was evident in areas where drought was present.

Adequate precipitation is very important during this part of the growing season, as some crops are entering critical growth stages. For example, moisture is especially needed when corn begins to tassel. Fortunately, dry areas in the eastern Dakotas received beneficial rainfall during this corn growth stage, and row crop conditions improved. Cooler, wetter weather in Kansas benefited developing sorghum. However, soil moisture continued to decline in July throughout much of the High Plains, which could cause crop conditions to worsen and impact yields should conditions not improve.

The occurrence of wildfires increased, particularly across Wyoming, Colorado, and South Dakota. Streamflows were running much below normal across the northern half of Wyoming and in western South Dakota in July. The early melting of mountain snowpack and very little precipitation during the month were to blame for low streamflows in Wyoming. The presence of drought in western South Dakota was taking its toll on streamflows there, and water quantity and quality issues were being reported. Streamflows were mostly normal in Colorado despite a dry July, although there were some exceptions in the southern part of the state. This area was much warmer, and the spring supply of snowmelt and soil moisture began to diminish, causing a decline in streamflows and reservoir levels.

Drought and abnormal dryness expanded and intensified across much of the region in July due to the lack of adequate rainfall in areas that needed it most. This was especially true in Wyoming, where the dry weather in July followed a very dry June. The July 26th release of the USDM indicated that approximately 35 percent of the High Plains region was experiencing drought or abnormal dryness (D0-D4), compared to about 28 percent at the end of June. Reports of impacts became more common as conditions continued to worsen. However, wetter conditions prevailed in areas of the eastern High Plains, which allowed for improvement of drought and dryness in some areas. The area in drought in the Black Hills of South Dakota extending into northeastern Wyoming was faring the worst in the region, as the area received little drought relief in July after enduring a very dry June. Impacts that have been reported include low alfalfa yields, little hay production, water quantity and quality issues, and wildfires. Moderate drought (D1) began to spread from this area into central South Dakota and the Nebraska panhandle. Another area of drought that intensified was in the Bighorn Mountains of northern Wyoming, where drought has been present since the snowpack season and precipitation has been abysmal so far this summer. As for improvements, ample precipitation fell in the eastern Dakotas in July, providing some relief from drought conditions in the area. Also, abnormal dryness (D0) was nearly erased in eastern Kansas due to impressive July rainfall totals.

As explained by the Southern Regional Climate Center, July temperatures were generally above average in the Southern region while precipitation totals for the month varied spatially over the region. Much of the northern half of the region experienced a wetter than normal month, and by contrast, it was drier than normal in the southern half of the region. Conditions were quite dry in eastern and southern Texas, with stations reporting little to no precipitation for the month. Many stations reported less than 10 percent of normal for the month. Drought conditions across the Southern region have worsened over the past month. In central Mississippi, many counties have been downgraded from moderate drought to severe drought as conditions there have been consistently drier than normal. There is also a new small pocket of moderate and severe drought in south eastern Oklahoma and north eastern Texas. Conditions in central Texas were quite dry this past month and many counties are now identified as abnormally dry. This is also the case in west-central and south western Arkansas.

In Texas, excessive rain early in July, followed by a prolonged period of dry conditions, took its toll on farmers. Non-irrigated fields in areas seeing little rain are dealing with partial to near total losses. Rice farmers are seeing highs over 100 degrees F (37.78 degrees C) and lows above 77 degrees F (25 degrees C), not allowing plants stressed during the day any reprieve at night. Excessive heat is also lowering the quality of livestock, which are spending more time cooling than feeding, and lowering hay quality. The development of flash drought was a concern in many parts of Texas during July, as many places had not seen more than half an inch of rainfall since the beginning of June, notably in northeast Texas near Texarkana. Drought conditions progressively worsened throughout the month as areas went longer and longer with no rainfall. Wildfires due to high surface evaporation were common throughout the month, including Del Valle, where 10 acres were burned (Information provided by the Texas Office of State Climatology).

As summarized by the Midwest Regional Climate Center, July was very wet for most of the Midwest and temperatures, when averaged for the month, were close to normal for most of the region. Statewide precipitation totals were above normal in every Midwest state except Ohio, which ranked tied for the 19th driest July on record (1895-2016). The northern two-thirds of Ohio and northeast Indiana received only 25 to 50 percent of its normal July rainfall total. The lack of rain in Ohio led to the introduction and expansion of moderate drought in the state during July (33 percent of Ohio). Drought also was introduced in Lower Michigan (16 percent of the state). The areas in the western half of the region that were in drought to begin the month saw improvements in their status with the heavy rains. Corn and soybean crops in the Midwest were rated about the same condition as each other in most of the states. Ohio and Michigan showed the most concern with both crops rated good or excellent in only 54 to 58 percent of fields. The other seven states in the region had good or excellent conditions for more than 70 percent of these two key crops. Ohio and Michigan were also reported to have the highest percentage of both topsoil and subsoil moisture in the region. These two states had about half their acreage in the short or very short categories while the other seven states reported less than 20 percent in those two categories.

As noted by the Southeast Regional Climate Center, precipitation was highly variable across the Southeast region during July, with numerous extremes recorded, and temperatures were well above average across the region with numerous record-breaking extremes observed. The driest locations were found across the southern portion of the region, including much of Georgia as well as parts of central Alabama, central and western South Carolina, the Florida Panhandle, and the eastern coast of the Florida Peninsula. Monthly precipitation totals were between 10 and 50 percent of normal in these areas. A total of 11 long-term (i.e., period of record exceeding 50 years) stations in Georgia and Florida observed their driest or second driest July on record. In contrast, the wettest locations were found predominately across the northern portion of the region. Drought conditions intensified and expanded in coverage across several areas of the Southeast region during July, including northern and central Georgia as well as western portions of the Carolinas. The percentage of the region under drought-free conditions (less than D1) decreased from 83 percent on June 28th to 81 percent on July 26th. The coverage of moderate-to-extreme (D1-D3) drought across Alabama remained around 40 percent during the month. Extreme drought conditions expanded in coverage by 9 percent during the month across parts of northern Georgia, and an area of moderate drought developed in the central portion of the state. Drought conditions (D1 and greater) doubled in coverage across western South Carolina, including the emergence of a localized area of extreme drought along the northwestern border with Georgia. A small area of southeastern Puerto Rico remained in moderate drought during the month. Field crops (corn, soybeans, cotton, and tobacco) were highly stressed by the persistent excessive heat and the lack of rainfall across much of the region, and this will likely reduce the quality of yields at harvest. The corn crop in Alabama and Georgia was especially affected by the hot, dry weather during the month, with substantial losses reported in many fields. In drought-stricken portions of the region, many livestock producers continued a supplemental feeding for their herds, as some pastures became infested with fall armyworms.

As explained by the Northeast Regional Climate Center, the Northeast wrapped up July with 3.74 inches (95.00 mm) of precipitation, 88 percent of normal, and it was a warmer-than-normal month. Eight states received below-normal precipitation, ranging from 51 percent of normal in Massachusetts, their 14th driest July on record, to 94 percent of normal in Maine. The USDM released on July 7 showed 21 percent of the Northeast was in a moderate or severe drought and 44 percent of the region was abnormally dry. Much of the region received below-normal precipitation during the month, leading to the expansion of drought and abnormally dry conditions. By the end of July, 29 percent of the region was in a moderate or severe drought and 37 percent of the region was abnormally dry. There were numerous impacts from the drought. Streamflow was at record or near record low levels and groundwater and reservoir levels were below normal in parts of New York, New England, northern New Jersey, and northern Pennsylvania. Water bans and restrictions were in place in more than 130 Massachusetts towns and more than 50 New Hampshire towns. Yields of corn and second cuttings of hay were expected to be lower than usual. Pastures and crops were stunted, and wild blueberries and apples were smaller in size. Many farmers irrigated, but some reported dried up wells and ponds. There was also increased fire activity. In Massachusetts, there were several lightning strike fires in late July, which is unusual for the state. Dead fuel moisture, the amount of water in dead vegetation (fuel), was historically low for late July in the state. When fuel moisture is low, fires can start easily and spread rapidly. A Drought Watch was declared for New York (for the first time since 2002) and northern New Jersey. In addition, a Drought Advisory was issued for southeastern Massachusetts and the Connecticut River Valley, while a Drought Watch was issued for central and northeastern Massachusetts.

As summarized by the Western Regional Climate Center, July average temperatures were slightly cooler than normal across the northern tier of the West this month, and slightly above normal across much of the Southwest. Scattered areas of above normal precipitation were recorded across Northwest. In the Southwest, a break in monsoon activity was observed in the first half of the month, with a return to monsoon conditions in the latter half of the month. Several large fires impacted the West this month, notably in California and Nevada.

Several Southwest locations saw below normal precipitation. Salt Lake City, Utah, recorded no measurable July precipitation for only the second time since records began in 1928. Normal July precipitation for Salt Lake City is 0.61 in (15 mm). Monsoon activity favored Arizona this month, leaving most of New Mexico drier than normal. In eastern New Mexico, Roswell saw only one day of precipitation totaling 0.45 in (11 mm), 22% of normal. This was the 16th driest July in a 124-year record. In southwestern New Mexico, Hachita reported only 33% of normal precipitation. Further north, Lander, Wyoming, reported no measurable July precipitation for the first time since its record began in 1946. Normal July precipitation for Lander is 0.78 in (20 mm). Most of California received little to no precipitation this month, typical for July. Drier than normal conditions allowed for drought to develop or increase in severity along the Oregon coast, western Montana, and eastern New Mexico. Along the eastern Wyoming-Montana border, extreme drought conditions are now present. Only very small areas of improvement were seen this month in the New Mexico panhandle and eastern Idaho.

Temperatures in coastal regions of Alaska were generally above normal this month, reflecting strong positive sea-surface temperature anomalies; inland areas saw more moderate temperatures. Anchorage recorded an average July temperature of 62.7 F (17.1 C), 3.9 F (2.2 C) above normal and the warmest July since records began in 1952. Much of Alaska's Interior observed above normal precipitation; Fairbanks recorded 4.97 in (126 mm) for the month, 230% of normal and the 3rd wettest July since records began in 1929. To the south, above normal precipitation was reported at many locations in Hawaii, much of it resulting from Tropical Storm Darby. Kaneohe, Oahu, recorded 10.75 in (273 mm) for the month, of which 7.65 in (194 mm) fell on the 25th. This was 400% of normal and the wettest July since records began in 1905.

Pacific Islands: The NOAA National Weather Service (NWS) offices, the Pacific ENSO Applications Climate Center (PEAC), and partners provided reports on conditions across the Pacific Islands.

In the U.S. Affiliated Pacific Islands (USAPI) (maps — Federated States of Micronesia, Northern Mariana Islands, Marshall Islands, Republic of Palau, American Samoa, basinwide), July 2016 was wetter than normal at Chuuk, near normal at Kwajalein, and drier than normal at the rest of the primary stations.

Rainfall amounts were below the minimum thresholds (4 or 8 inches) required to meet most monthly water needs at stations in the Marianas (Saipan), the Federated States of Micronesia (FSM) (Lukonor, Pingelap, and Ulithi), the Marshall Islands (Jaluit), and American Samoa (Pago Pago). July rainfall was above the monthly minimum thresholds at the rest of the regular reporting stations in Micronesia.

For many stations, this month broke a string of dry months (where the monthly precipitation was below the minimum threshold). These included Ailinglapalap and Utirik in the Marshall Islands; Rota in the Mariana Islands; and Maap and Woleai in the FSM. The 4- and 8-inch thresholds are important because, if monthly precipitation falls below the threshold, then drought becomes a concern.

As measured by percent of normal precipitation, Kapingamarangi, Koror, Kosrae, Lukonor, Majuro, Pohnpei, and Yap have been drier than normal in the short term (July and the last 3 months [May-July 2016]) as well as the long term (year to date [January-July 2016] and last 12 months [August 2015-July 2016]). Kwajalein was near normal in the short term but drier than normal in the long term. Pago Pago was near normal in the long term but drier than normal in the short term. Saipan was near normal for the last 12 months but drier than normal for the other three time periods. Guam was near normal for the year to date but drier than normal for the other three time periods. Chuuk was near to wetter than normal for all four time periods.


X
  • Percent of Normal Precip
  • Precipitation
  • Normals
Pacific Island Percent of 1981-2010 Normal Median Precipitation
Station Name Aug
2015
Sep
2015
Oct
2015
Nov
2015
Dec
2015
Jan
2016
Feb
2016
Mar
2016
Apr
2016
May
2016
Jun
2016
Jul
2016
Aug 2015-
Jul 2016
Chuuk155%188%53%70%82%63%29%85%86%107%91%94%91%
Guam NAS146%108%125%81%74%65%120%79%52%53%125%67%86%
Kapingamarangi162%112%63%89%134%103%65%88%94%34%24%66%73%
Koror73%143%53%69%41%26%30%36%135%115%93%45%66%
Kosrae138%115%63%33%95%60%113%32%23%72%130%88%66%
Kwajalein171%95%105%88%59%64%17%45%21%57%142%101%89%
Lukonor75%149%40%123%56%123%61%51%113%102%73%43%72%
Majuro207%96%83%40%61%14%46%20%22%110%66%90%75%
Pago Pago125%18%88%210%183%34%54%101%329%102%73%81%105%
Pohnpei199%124%78%67%71%102%49%44%60%80%143%79%89%
Saipan141%92%198%64%154%54%105%106%68%87%57%42%105%
Yap148%68%43%37%58%35%34%15%62%113%54%67%65%
Pacific Island Precipitation (Inches)
Station Name Aug
2015
Sep
2015
Oct
2015
Nov
2015
Dec
2015
Jan
2016
Feb
2016
Mar
2016
Apr
2016
May
2016
Jun
2016
Jul
2016
Aug 2015-
Jul 2016
Chuuk19.9122.076.097.469.256.402.097.0810.7312.1110.6111.27125.07
Guam NAS21.5413.7114.265.963.772.623.631.631.311.807.736.7784.73
Kapingamarangi13.1411.085.138.2813.209.406.0410.0212.784.073.309.33105.77
Koror9.9016.886.247.864.592.642.532.689.9013.5516.258.28101.3
Kosrae19.6916.366.904.5515.379.9514.565.153.9912.7018.9913.07141.28
Kwajalein16.6310.2411.719.983.902.020.461.051.133.809.819.9680.69
Lukonor10.5515.154.5311.186.3510.375.444.7512.8311.928.496.84108.4
Majuro24.2410.7210.525.336.931.113.171.332.0511.127.2710.0993.88
Pago Pago6.751.208.1521.3323.534.496.4910.7630.879.893.884.48131.82
Pohnpei28.3315.5911.869.9511.4113.494.645.7611.0116.0621.1812.12161.4
Saipan18.519.2621.003.615.941.362.722.001.782.072.053.7674.06
Yap21.999.215.293.314.932.231.770.703.478.906.4610.0378.29
Pacific Island 1981-2010 Normal Median Precipitation (Inches)
Station Name Aug
2015
Sep
2015
Oct
2015
Nov
2015
Dec
2015
Jan
2016
Feb
2016
Mar
2016
Apr
2016
May
2016
Jun
2016
Jul
2016
Aug 2015-
Jul 2016
Chuuk12.8611.7111.5110.6111.2510.107.258.3212.4711.3011.6611.98136.77
Guam NAS14.7412.6611.447.385.114.013.032.072.533.406.1810.1499.09
Kapingamarangi8.139.938.199.279.849.159.2711.4313.6412.0813.7814.15145.85
Koror13.5011.7711.8411.3911.1610.188.567.447.3211.8317.4818.53152.90
Kosrae14.2214.2210.9413.8316.1116.6712.9316.0617.5117.7514.6414.91213.87
Kwajalein9.7410.7411.1811.286.663.162.642.355.266.726.939.8790.41
Lukonor14.0410.1511.329.0811.278.418.939.2611.3111.6911.6515.93151.36
Majuro11.6911.1712.7313.4411.397.746.886.589.4210.1111.0111.17125.25
Pago Pago5.386.539.2610.1412.8413.3412.0010.689.399.665.335.55125.57
Pohnpei14.2612.5515.2714.8316.0813.189.5513.1718.4119.9614.8115.43182.36
Saipan13.1310.0910.625.613.852.532.591.892.632.383.628.9170.25
Yap14.8213.5012.188.838.516.395.194.565.637.8512.0415.08120.31

The end of the El Niño and development of ENSO-neutral conditions in the tropical Pacific has resulted in the return of much-needed rainfall to most of the USAPI region. The rains have ended the drought, although long-term drought impacts linger on some islands due to the extreme dryness of this recent El Niño episode as seen in the table below.

An analysis of historical data for the USAPI stations in the Global Historical Climatology Network-Daily (GHCN-D) dataset, augmented with fill-in data from the 1981-2010 Normals, indicated that several stations had record or near-record dryness during 2016 and 2015-2016. The following table lists the precipitation ranks for July 2016, January-July 2016 (year to date), and August 2015-July 2016 (the last 12 months). Some stations have a long period of record and their dataset is fairly complete, while other stations have a shorter period of record and the dataset has some missing data. The year to date was the driest January-July on record for Ulithi (based on a record from 1981-2016) and second driest for Jaluit (1981-2016), Majuro (1954-2016), and Utirik (1985-2016). The last twelve months (August 2015-July 2016) was the driest such August-July period on record at Jaluit, Woleai (1968-2016), Yap (1951-2016), Ulithi, and Pingelap (1981-2016), and second driest at Kosrae (1954-2016) and Saipan (1981-2016).

Rank, Number of Years with data, and Period of Record for USAPI stations for July 2016, January-July 2016, and August 2015-July 2016.
Rank of 1 = driest.
Station July 2016
Rank
July
No. of Years
Jan- Jul 2016
Rank
Jan- Jul
No. of Years
Aug 2015- Jul 2016
Rank
Aug- Jul
No. of Years
Period of Record
Jaluit 4 33 2 33 1 31 1981-2016
Koror 6 66 7 65 3 65 1951-2016
Woleai 24 35 3 26 1 22 1968-2016
Yap 12 66 3 65 1 65 1951-2016
Majuro 19 63 2 62 3 62 1954-2016
Ulithi 3 34 1 33 1 32 1981-2016
Ailinglapalap 20 32 3 32 N/A 29 1981-2016
Pingelap 2 33 4 32 1 31 1981-2016
Kosrae 15 48 4 36 2 29 1954-2016
Lukonor 2 32 4 32 3 19 1981-2016
Saipan 3 36 4 35 2 27 1981-2016
Pohnpei 13 66 6 65 9 65 1951-2016
Kwajalein 33 65 9 64 11 64 1952-2016
Kapingamarangi 10 27 3 19 4 13 1962-2016
Chuuk 22 66 10 65 13 65 1951-2016
Guam 10 60 7 59 10 59 1957-2016
Nukuoro 15 33 10 32 20 31 1981-2016
Pago Pago 20 51 22 50 34 50 1966-2016
Wotje 31 33 23 33 N/A 30 1981-2016
Utirik 12 13 2 6 N/A 2 1985-2016

Precipitation amount for current month for U.S. Affiliated Pacific Island stations

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

Percent of normal precipitation for last 3 months for U.S. Affiliated Pacific Island stations

Percent of normal precipitation for the year to date for U.S. Affiliated Pacific Island stations

Percent of normal precipitation for last 12 months for U.S. Affiliated Pacific Island 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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Contacts & Questions
For additional, or more localized, drought information, please visit:

Citing This Report

NOAA National Centers for Environmental Information, State of the Climate: Drought for July 2016, published online August 2016, retrieved on September 30, 2016 from http://www.ncdc.noaa.gov/sotc/drought/201607.