Drought - May 2014


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Issued 12 June 2014
Contents Of This Report:
Map showing Palmer Z Index
Percent Area of U.S. in Moderate to Extreme Drought, January 1996 to present

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


During May 2014, a strong westerly flow in the upper-level circulation sent several weather systems rippling across the CONUS, some of which would stall in the upper-level trough/ridge pattern and amplify, then move slowly across a region. These systems brought heavy precipitation to parts of the country, especially the Gulf of Mexico coast. The haphazard character of the slow-moving upper-level systems split the storm track east of the Rockies, resulting in drier-than-normal weather from the Southern Appalachians to Central Plains, and contributing to the occurrence of large wildfires early in the month. Ridging in the upper atmosphere dominated in the West, bringing mostly below-normal precipitation and above-normal temperatures. Drought expanded in some areas, but beneficial rains from the upper-level lows and cold fronts contracted drought in others. The net change was contraction of moderate to exceptional drought in the Midwest, Central to Southern Plains, and West, but an increase in the intensity of drought (expanded extreme to exceptional drought) in the Central Plains and West. Upper-level ridging brought dry weather to much of Alaska, while Hawaii was generally wetter than normal in the northern islands and drier than normal in the south with statewide drought conditions continuing to improve. When integrated across the CONUS, May 2014 ranked as the 48th driest May in the 1895-2014 record. On balance, the national drought footprint shrank when compared to last month, decreasing to about 31.2 percent of the U.S. as a whole, according to USDM statistics. According to the Palmer Drought Index, which goes back to the beginning of the 20th century, about 34 percent of the CONUS was in moderate to extreme drought at the end of May, an increase of about 5 percent compared to last month.

The U.S. Drought Monitor drought map valid June 3, 2014
The U.S. Drought Monitor drought map valid June 3, 2014.

By the end of the month:



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 the West and parts of the Plains than the PHDI map because the meteorological conditions that produce drought 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 wet or near normal conditions occurred during May over parts of the Southern Plains which had areas in long-term drought during April, resulting in contraction of drought by the end of May. Short-term dry conditions occurred over much of the West, Central Plains, and Tennessee Valley, which had areas in long-term drought or neutral conditions during April, resulting in an intensification and expansion of drought by the end of May. Wet short-term conditions occurred over parts of the long-term near normal to wet areas of the Northern Plains, Mid-Atlantic, and Southeast, resulting in expansion of the wet spell areas there.



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 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. Spring precipitation was spotty across the West, with the last one, two, and three months having near-normal to wet conditions in some areas (especially the Northwest) and dry conditions in others. The spring precipitation was not enough to erase deficits built up during the winter wet season, with much of the West (especially the Southwest) quite dry at the six-month time scale. At longer time scales (9-12 months), precipitation from the fall and summer 2013 monsoon season give neutral conditions to the Southwest, while California shows up as dry. The multi-year drought in the West begins to be manifested at the 24-month time scale. The Central Plains is persistently dry at all time scales. Recent precipitation in the Southern Plains neutralized the dryness at the one- to two-month time scales, but Southern Plains dryness is evident at three months and especially at six months. The great drought of 2012 can still be seen in the Plains on the 24-month SPI map. Dryness is evident at one to three months in the Tennessee Valley to Central Appalachians, while the 2013 dryness in the Midwest can be seen at the 9- to 12-month time scales. Wet conditions largely dominate east of the Mississippi River at two months and longer (12-24 months) time scales, with neutral to somewhat dry conditions more prevalent at the intervening time scales. For the Colorado and Wyoming Rockies to the Northern Plains, wet conditions are the rule at 9 to 12 months, while recent weather has been on the neutral to dry side.


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


Agricultural, Hydrological, and Meteorological Indices and Impacts

USDA Topsoil Moisture Short-Very Short map
USDA Topsoil Moisture Short-Very Short map
USGS monthly streamflow percentiles
USGS monthly streamflow percentiles

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

The cumulative impact of the persistent reduced precipitation (last 1, 2, 3, 5, 6, 8 months) in the nation's agricultural areas can be seen in dried soils (both modeled and observed) and stressed vegetation in parts of the West and much of the Plains. According to June 2 U.S. Department of Agriculture (USDA) reports, more than 60 percent of the topsoil was short or very short of moisture in California (75%), Oklahoma (68%), New Mexico (66%), and Kansas (60%), and 50 percent or more was short or very short in Nevada (55%), Texas (53%), Utah (51%), and Washington (51%). Subsoil moisture conditions were worse, with more than 80 percent of the subsoil moisture short or very short in California (85%), and Oklahoma (84%), and more than 70 percent in Kansas (75%) and Nevada (75%), reflecting the long-term (multi-year) nature of the drought. The wind, low humidities, and prolonged dryness contributed to the development of large wildfires in the Plains, Southwest, and Southern Appalachian regions throughout the month.

Precipitation in the Southern Plains improved soil moisture and crop conditions, but the continued dry conditions across the West and Central Plains ravaged crops and other vegetation. The modeled Soil Water Index indicated unsatisfactory soil moisture conditions across the southwestern third of the country, where impacts could be stress or wilting, and the Water Requirement Satisfaction Index indicated potential crop failure across much of the Southwest and Southern Plains. As of June 3rd, about 51 percent of winter wheat was in drought, down from 53 percent a month ago, 43 percent of the cattle inventory was in drought (down 1 percent), 29 percent of hay (down 1 percent), 22 percent of corn (down 4 percent), and 16 percent of soybeans (down 3 percent). June 2nd USDA reports indicated that 44 percent of the winter wheat crop was in poor to very poor condition, nationally (up 10 percent from a month ago), with state values of 78 percent in Oklahoma, 64 percent in Texas, 62 percent in Kansas, and 39 percent in Colorado. Nationally, 19 percent of the pasture and rangeland was in poor to very poor condition, with statewide values over 50 percent in California (70%), New Mexico (68%), and Arizona (55%), and 40 percent or more in Kansas (43%), Oklahoma (43%), and Nevada (40%). The Palmer Crop Moisture Index (CMI) showed abnormally to excessively dry conditions expanding northward in the West as the month progressed (weeks 1, 2, 3, 4, 5).

USDA West statewide reservoir status
USDA West statewide reservoir status.

The subnormal precipitation was reflected in below-normal monthly precipitation totals as well as lack of rain days and long runs of consecutive dry days, especially in the Southwest. Streamflow and modeled runoff averaged below normal in parts of the West, Plains, and Southern Appalachians, with some basins averaging much below normal and some stream gauges measuring record low monthly values for May. Precipitation for the water year-to-date (October 1 to present) has generally been near to above normal for the Northern to Central Rockies. On a basinwide basis, the northern basins in the Pacific Northwest had near average precipitation for the water year-to-date, but on an individual station-by-station basis, many stations were drier than normal. Of the western basins, the Central Rockies basins have had the wettest water year, based on percent of normal. Stations and basins in the Southern Rockies and Southwest, especially California, predominantly have had a drier-than-normal water year. The persistent dryness — for the water year-to-date and longer — was reflected in below-normal groundwater and springwater observations, and — for Texas (especially the western counties), California, and most of the western states — below-normal reservoir levels. Some wells in the western and central states, and some springs in the western states, had record low levels, with some of the wells having the lowest groundwater levels in at least 50 years.



Regional Discussion


Hawaii: The precipitation pattern for May 2014 and April-May 2014 was mixed across Hawaii, with a lack of trade winds keeping the windward sections of the Big Island drier than normal while rainfall was above normal on the northern islands. The last 3 months was predominantly wetter than normal. A mixed pattern of above- and below-normal precipitation dominated at the longer periods (last 5, 6, 8, 11, and 12 months). The recent rainfall has been beneficial and helped contract drought, but it has not been enough to erase deficits built up over the last 2 to 3 years. On the USDM map, moderate drought covered less than one percent of the state this month, but the area abnormally dry to moderate drought expanded to 50 percent this month compared to 34 percent last month.

Alaska: May was drier than normal for stations from central Alaska to the panhandle, and wetter than normal for stations along the northwest coast. A dry pattern dominated since last winter (last 2, 3, 5, and 6 months). A mixed pattern was evident at 8 months, dryness dominated from the interior stations to panhandle at intermediate time scales (last 11, 12, and 24 months), but the pattern was mixed again at 36 months. The water-year-to-date (October-May) wetness and May dryness are reflected in the high elevation (SNOTEL) stations. Abnormal dryness covered a fifth (about 21 percent) of the state on the USDM map, mainly reflecting water supply (reservoir) concerns in the southern panhandle and dryness towards the interior.

Puerto Rico: May 2014 was wetter than normal across parts of the northern coast of Puerto Rico but drier than normal across the southern half of the island. The dryness shifts to the eastern half of the island at longer time scales (last 2 to 3 months), then toward the central interior to south central regions at the longest time scales (last 5, 6, and 8 months). Rainfall deficits in excess of twelve inches are evident in interior regions for the last five months and in excess of 20 inches for the last eight months. May streamflows were below normal at several stations. The abnormally dry area covered about a quarter of the island on the USDM map.

CONUS State Ranks:

1-month state precipitation ranks Kansas statewide precipitation, May, 1895-2014

The May precipitation anomaly pattern of dryness in the Southwest, Northern Rockies, Great Plains, Midwest, and Tennessee Valley was reflected in the state ranks. Kansas had the sixth driest May in the 1895-2014 record, but enough pockets of wetness occurred in the dry areas to prevent any other state from ranking in the top ten dry category. Eleven states had May precipitation ranks in the dry third of the historical record.

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). California had their ninth warmest May on record. The unusual warmth in the Southwest exacerbated the drought conditions as seen by more severe SPEI drought values when compared to the SPI values. Likewise, the unusually colder-than-normal temperatures in the Plains reduced water demand, as reflected by less severe SPEI drought values when compared to the SPI values.

3-month state precipitation ranks Kansas statewide precipitation, March-May, 1895-2014

At the three-month time scale, persistent dryness in the Central Plains gave Kansas their third driest spring and Oklahoma their ninth driest spring on record. March-May dryness in the Southwest, Southern Plains, Midwest, and Tennessee Valley to Central Appalachians marked nine other states with a precipitation rank in the driest third of the historical record. Like May, the unusual spring warmth in the West exacerbated the drought conditions as seen by more severe SPEI drought values when compared to the SPI values, and the unusually colder-than-normal temperatures in the Plains reduced water demand, as reflected by less severe SPEI drought values when compared to the SPI values.

year-to-date state precipitation ranks Oklahoma statewide precipitation, January-May, 1895-2014

The January-May 2014 precipitation anomaly pattern of dryness in the Southwest, Great Plains, and Appalachians was reflected in the state ranks. Thirteen states ranked in the driest third of the historical record, with three of them having the tenth driest, or drier, year-to-date. These "top ten driest" states included Kansas (second driest January-May), Oklahoma (third driest), and Arizona (fourth driest). Five states in the West had the tenth warmest, or warmer, January-May, including California which ranked record warm. As with May and March-May, the year-to-date warmth in the Southwest exacerbated the drought conditions as seen by more severe SPEI drought values when compared to the SPI values, and the below-normal temperatures in the Plains reduced the SPEI drought values when compared to the SPI values.

Arizona statewide precipitation, January-May, 1895-2014 Kansas statewide precipitation, January-May, 1895-2014

Current 6-month state precipitation ranks Kansas statewide precipitation, December-May, 1895-2014

The precipitation pattern for the last six months is similar to that for the last five months, except it is drier. Most of the West and Great Plains was drier than normal during December 2013-May 2014, with four states having the tenth driest, or drier, December-May in the 1895-2014 record — Kansas (second driest), Oklahoma (second driest), Arizona (fourth driest), and California (sixth driest). Eight other states ranked in the driest third of the historical record, including Nebraska (eleventh driest). The temperature anomaly pattern of unusual warmth in the West and coolness east of the Rockies was evident at the 6-month time scale, with California having the warmest December-May. Evapotranspiration is greatly reduced during winter, yet the temperature extremes still resulted in enhanced SPEI drought values in the Southwest and reduced SPEI values east of the Rockies when compared to the SPI values.

Oklahoma statewide precipitation, December-May, 1895-2014 Arizona statewide precipitation, December-May, 1895-2014

California statewide precipitation, December-May, 1895-2014 California statewide temperature, December-May, 1895-2014

12-month state precipitation ranks California statewide precipitation, June-May, 1895-2014

For the last twelve months (June 2013-May 2014), dryness dominated California, the Southern to Central Plains, and Midwest, with pockets of wetness in most of the dry areas. California was especially hard hit, having the hottest and third driest June-May on record, and Iowa ranked tenth driest. Seven other states ranked in the driest third of the historical record. States in the Southwest ranked near- to above-normal because of pockets of wetter-than-average weather which influenced the statewide ranks. The West has experienced unusual warmth for most of the last twelve months, with ten states ranking in the warmest third of the historical record. Six of these states — California, Oregon, Nevada, Idaho, Utah, and Arizona, as well as Florida — had the tenth warmest, or warmer, June-May. The record warmth in California exacerbated the drought conditions as seen by more severe SPEI drought values when compared to the SPI values. Likewise, as is the case for the other time periods examined here, the persistent and unusually colder-than-normal temperatures east of the Rockies have reduced the severity of drought in the Plains as seen by less severe SPEI values when compared to SPI values.

Iowa statewide precipitation, June-May, 1895-2014 California statewide temperature, June-May, 1895-2014

Western U.S.


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

As noted above, dry weather has dominated the West for the last several months, resulting in a reduced winter mountain snowpack and low lake, reservoir, and stream levels. According to the USDM, 60.3 percent of the West was experiencing moderate to exceptional drought at the end of May, a decrease of about 1.1 percent compared to the previous month. Beneficial precipitation improved conditions in some areas, while continued dryness and increased water demand due to the unusually warm temperatures expanded and intensified drought in other areas. This resulted in a net decrease in drought area as measured by the USDM. The Palmer Drought Index percent area statistic was 64.0 percent, an increase of about 10 percentage points from the previous month.

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

PHDI for California Division 6, January 1900-present
PHDI for California Division 6, January 1900-present.

Parts of the West, especially the southern portions, have been in drought for the last several years, with the PHDI reaching record or near-record low values at times. Time series of precipitation departure show the variation over time (New Mexico, California), while maps of the SPEI show the spatial extent (36-month SPEI, 48-month SPEI) of the long-term dryness. The May 2014 PHDI has surpassed the lowest values reached during the 1976-77 drought of record for parts of California — the Central Coast Drainage (climate division 4), the San Joaquin Drainage (climate division 5), and the South Coast Drainage (climate division 6). Some of these analyses show a disturbing trend toward more extreme droughts over the last 40 years in California.

In the Southern Plains, the summer of 2013 was a wet reprieve for such states as Texas, Oklahoma, and Kansas. The 2012 rainy season was, and now the 2014 rainy season is, much drier than normal for these states, with the dryness extending further back in time for some of them.


Agricultural Belts


Primary Hard Red Winter Wheat Belt precipitation, current month, 1895-2014
Primary Hard Red Winter Wheat Belt precipitation, current month, 1895-2014.
Primary Hard Red Winter Wheat Belt precipitation, growing season, 1895-2014
Primary Hard Red Winter Wheat Belt precipitation, growing season, 1895-2014.

The May precipitation pattern for the Primary Hard Red Winter Wheat agricultural belt was drier than normal, with May 2014 ranking as the 27th driest and 44th warmest May region-wide. The growing season to date (October 1-present) ranked as the fifth driest October-May in the 1895-2014 record. Three of the last four growing seasons have been much drier than normal.

Primary Hard Red Winter Wheat Belt PHDI, January 1900-present
Primary Hard Red Winter Wheat Belt PHDI, January 1900-present.

The last several months have been persistently dry in the Primary Hard Red Winter Wheat belt. March-May, February-May, and January-May 2014 each ranked as the third driest such periods in the 1895-2014 record. April-May ranked as the fourth driest such two-month period on record. Regionwide, the PHDI has been in drought for just over three years (since April 2011), but the droughts of the 1930s and 1950s were more severe and lasted longer according to this index.

Primary Corn and Soybean Belt precipitation, current month, 1895-2014
Primary Corn and Soybean Belt precipitation, current month, 1895-2014.
Primary Corn and Soybean Belt precipitation, growing season, 1895-2014
Primary Corn and Soybean Belt precipitation, growing season, 1895-2014.

The growing season for the Primary Corn and Soybean agricultural belt got off to a dry start during March, it was wet across much of the region during April 2014, and May saw a return to dry conditions regionwide. When these three months are aggregated together, spring 2014 ranked as the 49th driest and 36th coolest March-May on record.

River Basins


Rio Grande River Basin precipitation, January-May, 1895-2014
Rio Grande River Basin precipitation, January-May, 1895-2014.
Arkansas-White-Red River Basin precipitation, water year (October-present), 1895-2014
Arkansas-White-Red River Basin precipitation, water year (October-present), 1895-2014.

As noted by the USGS, streamflow in some river basins in the West and Central Plains was much below normal at the end of May. The Arkansas-White-Red river basin had the 12th driest spring (March-May) and 14th driest water year to date (October-present) in the 1895-2014 record. The Rio Grande river basin had the 11th driest year to date (January-May) and 27th driest water year to date. The water year to date ranked as the 24th driest for the Pacific Northwest basin, 14th driest for the Lower Colorado River basin, and 33rd driest for the Tennessee River basin.

NOAA Regional Climate Centers:


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

SoutheastSouthMidwestNortheastHigh Plains
WestPacific Islands




As described by the High Plains Regional Climate Center, the majority of the High Plains region was dry this month with the driest portions including central Wyoming, eastern Kansas, pockets of the Dakotas, and a swath stretching from eastern Colorado, through much of Kansas, and north into Nebraska. These areas received at most 50 percent of normal precipitation. This lack of precipitation caused some locations to be ranked in the top 10 driest Mays on record. Grand Island, Nebraska had its 5th driest May with 0.74 inch (19 mm) which was 3.67 inches (93 mm) below normal, or 17 percent of normal precipitation (period of record 1896-2014). The driest May on record occurred in 1934 with 0.34 inches (9 mm). Topeka, Kansas also ranked in the top 10 driest Mays on record. With only 1.63 inches (41 mm), or 33 percent of normal, this ranked as the 9th driest May for Topeka. The record of 0.41 inch (10 mm) was set in 1966 (period of record 1887-2014). The main exception to the dryness was a swath of above normal precipitation running from western to northern Colorado into the panhandle of Nebraska ending in central South Dakota. Overall, there were only slight changes to the USDM in the High Plains region this month. Although some areas had improvements and others had degradations, the areas experiencing moderate (D1) to exceptional (D4) drought remained at about 33 percent. The most significant changes occurred in Kansas where there was a 20 percent increase in extreme drought conditions (D3). Exceptional drought conditions (D4) were also introduced across the southern border of the state. In Nebraska, D1 and D2 were trimmed in areas receiving ample precipitation, but a new area of D3 emerged in the central part of the state. D1 also expanded northward into southeastern South Dakota. A small area of D3 also expanded to include all of southeastern Colorado.

As explained by the Southern Regional Climate Center, precipitation totals for the month of May illustrate that for parts of the Southern region, it was a very wet month, while for other areas, it was very much the opposite. In Texas, central and southern counties received between two and three times the normal amount of precipitation. This was also the case for the south central and south eastern Louisiana, and southern Mississippi. In central Arkansas, precipitation totals varied from near normal to approximately one and a half times normal. Elsewhere, precipitation was scarce. The western panhandle of Texas, for instance, averaged between zero and fifty percent of normal, with most stations averaging near one quarter of normal precipitation. This was also the case in central Tennessee, and in east central and northern Oklahoma. Oklahoma experienced its twenty-eighth driest May on record (1895-2014), while for Tennessee, it was their twenty-first driest May (1895-2014).

Drought conditions in the Southern region did not significantly change in the states of Arkansas, Mississippi, Louisiana, or Tennessee, with all four states remaining relatively drought free. Heavy rains in Texas and north western Oklahoma have led to a dramatic reduction in areal coverage of exceptional drought over the past month. There was also a significant reduction in the amount of severe and extreme drought in central Texas. Despite these improvements, approximately one fifth of the Southern region (mostly Oklahoma and northern Texas) is still experiencing extreme to exceptional drought. Almost half the region (46.47 percent) is currently experiencing some form of drought. In Texas, winter wheat production is estimated to be down from 2013. The USDA estimated that though the 29 bushels per acre is unchanged from last year, only 55.1 million acres, down from 65.3 million acres, are expected to be harvested; the Blacklands were the worst off, dropping 36 percent in their estimated acres harvested. Other Texas grains harvests are expected at 1.9 million acres, down 16 percent from this time last year. By the end of the month, only 62% of cotton acreage had been planted, down from 74% last year and the 75% 5-year average. The recent rains have greatly helped the corn crop, with less than 10% poor to very poor and almost 50% being good to excellent, up from around 20% at the beginning of the month (Information Provided by the Texas Office of State Climatology). The drought in Texas, continues to have heavy impacts. Wichita Falls, despite the recent rains, officially began Stage 5, Drought Catastrophe water restrictions this month. Several small communities across the state are in danger of running out of drinking water within 45-90 days, leading small loans to be given out by the Texas Department of Agriculture, such as the $350,000 well loan for Pebble Beach in Bandera County. As planning for the future of Texas's water supply continues, debate on the true number for future water use falls under scrutiny, as new reports argue that less than half of 2.7 trillion estimated gallons of water would be needed; this would encompass all of the controversial $3.3 billion reservoir proposed for the Dallas-Fort Worth metropolitan area (Information Provided by the Texas Office of State Climatology).

As summarized by the Midwest Regional Climate Center, May precipitation was below normal for much of the Midwest. The driest areas were pockets of less than half of normal precipitation in northern Missouri, west central Illinois, southeast Iowa, and northwest Iowa. Wet areas for the month were mostly in the northern states with some areas receiving more than 150 percent of normal. Spring precipitation was slightly wetter than the pattern for May with the northern states mostly above normal along with a swath from southeast Missouri to northeast Ohio. Drier spring conditions were most pronounced in northwest Iowa where totals were less than half of normal. Other areas with less than 75 percent of normal extended into Minnesota, Missouri, and Illinois. Drought conditions in May showed slight improvements in both coverage and intensity. Despite the improvements overall, western Missouri saw some degradation. Areas in the western half of the region and in southeast Kentucky were being watched closely for drought impacts. Planting of corn and soybeans was behind normal as the month began but favorable field conditions allowed farmers to catch up to normal during the month. Much of the corn crop was planted by the end of the month, slightly ahead of normal. Soybean planting was ahead of normal in the south but remained behind normal in the north.

As noted by the Southeast Regional Climate Center, mean temperatures were above average and monthly precipitation totals were variable across the Southeast in May. The driest locations were found across South Florida, southern sections of Puerto Rico, and coastal sections of Virginia and the Carolinas, where monthly totals were less than 50 percent of normal. Only minor changes were noted in the USDM across the Southeast in May. There was a slight expansion of abnormally-dry conditions (D0) across northern portions of Alabama and Georgia, as well as extreme western North Carolina and Virginia. A small region of moderate drought (D1) emerged across extreme southern Florida, where precipitation deficits over the past several months have been the greatest. The Florida Climate Center reported that planting of field crops across the Panhandle was running 2 to 4 weeks behind schedule due to excessive rainfall and flooding. Reports of wet field conditions, disease, and delays in planting and hay cutting were also reported across parts of Georgia.

As explained by the Northeast Regional Climate Center, the Northeast wrapped up May with above-normal precipitation, receiving 4.50 inches (114.3 mm) or 111 percent of normal. For the dry states, departures ranged from 91 percent of normal in Delaware and Massachusetts down to 83 percent of normal in Rhode Island. According to the USDM released May 1, parts of northeastern West Virginia, western Maryland, and southern Pennsylvania (2 percent of the Northeast) were abnormally dry. The following week, dry conditions expanded in West Virginia and Pennsylvania to cover 9 percent of the region. However, by mid-month precipitation had eased dryness in all but southern West Virginia (1 percent of the region).

As summarized by the Western Regional Climate Center,

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

As noted by the National Weather Service office in Honolulu, in April the last area of severe drought, or the D2 category in the USDM map, was eased to moderate drought, or the D1 category, for the Kualapuu reservoir service area in west Molokai. This downgrade ended D2 conditions that had been present continuously in various locations in the state of Hawaii since June 2008. There were no other drought areas in the state. The USDM map showed just a sliver (less than one percent) of D1 (moderate drought) remaining as of June 3rd.


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

On other Pacific Islands (maps — Micronesia, Marshall Islands, basinwide), May 2014 was wetter than normal at Chuuk, Lukonor, and Saipan, and drier than normal at the other reporting stations. As measured by rainfall amount, a drying trend occurred over the western islands this month. The May rainfall amounts were below 4 inches (a critical threshold amount for the Mariana Islands) at Guam and Yap, below 8 inches (another critical threshold amount) at Koror, Kwajalein, Majuro, Pago Pago, and Saipan, and above 8 inches at the other stations. The 4- and 8-inch thresholds are important because, if monthly precipitation falls below the threshold, then drought becomes a concern. Even though May 2014 rainfall was below these thresholds at Saipan, it was above normal because this is the dry season at Saipan and their May normal is very low — well below the thresholds.

As measured by percent of normal precipitation, when compared to April 2014 and the last three months (March-May 2014), May 2014 exhibited a drying trend for Koror, Kosrae, Kwajalein, Majuro, Pago Pago, and Yap. When compared to the year to date (January-May 2014), May 2014 exhibited a drying trend for Koror, Kwajalein, Majuro, and Yap. May's drier-than-normal precipitation anomalies contrast with the wetter-than-normal anomalies of the last twelve months (June 2013-May 2014) for Guam, Kwajalein, Majuro, and Yap.


X
  • Percent of Normal Precip
  • Precipitation
  • Normals
Pacific Island Percent of 1981-2010 Normal Median Precipitation
Station NameJun
2013
Jul
2013
Aug
2013
Sep
2013
Oct
2013
Nov
2013
Dec
2013
Jan
2014
Feb
2014
Mar
2014
Apr
2014
May
2014
Jun 2013-
May 2014
Chuuk84%84%80%141%103%111%75%59%492%89%111%116%113%
Guam NAS102%53%74%255%198%56%65%421%170%141%108%99%117%
Kapingamarangi47%50%83%55%85%38%254%168%112%81%43%83%77%
Koror67%64%99%64%86%115%64%170%91%68%224%63%84%
Kosrae122%69%62%104%201%112%87%86%104%82%150%93%88%
Kwajalein67%98%57%82%37%121%39%121%523%475%366%80%113%
Lukonor64%37%62%117%118%125%90%257%206%138%72%116%95%
Majuro96%103%65%87%71%96%51%125%177%91%246%75%100%
Pago Pago220%153%337%125%62%58%99%146%97%65%152%81%104%
Pohnpei113%61%38%121%81%142%36%78%225%112%87%87%91%
Saipan157%50%53%167%109%52%71%546%55%167%168%205%112%
Yap134%53%86%181%144%74%65%340%91%153%226%39%117%
Pacific Island Precipitation (Inches)
Station NameJun
2013
Jul
2013
Aug
2013
Sep
2013
Oct
2013
Nov
2013
Dec
2013
Jan
2014
Feb
2014
Mar
2014
Apr
2014
May
2014
Jun 2013-
May 2014
Chuuk9.8510.0410.2516.4911.8211.828.445.9835.707.4313.8013.06154.68
Guam NAS6.325.3910.8432.2522.664.133.3316.895.142.912.743.36115.96
Kapingamarangi6.457.116.725.426.993.4925.0215.3810.369.265.839.97112
Koror11.7011.9413.357.5310.1913.117.1917.277.795.0816.387.45128.98
Kosrae17.8910.338.8014.8222.0315.5413.9414.3913.4713.1226.2916.59187.21
Kwajalein4.669.715.518.814.1713.632.623.8113.8211.1719.245.36102.51
Lukonor7.515.888.6411.9213.3411.3810.1121.6518.4212.768.1813.58143.37
Majuro10.5511.517.629.709.0112.845.769.6612.195.9623.207.58125.58
Pago Pago11.758.4818.148.145.715.9112.7119.5411.656.9514.297.84131.11
Pohnpei16.799.425.4115.2312.3720.995.7910.2721.5014.7015.9617.33165.76
Saipan5.684.426.9916.8711.602.912.7413.811.433.164.414.8778.89
Yap16.168.0112.6924.3917.606.565.5621.744.726.9912.723.07140.21
Pacific Island 1981-2010 Normal Median Precipitation (Inches)
Station NameJun
2013
Jul
2013
Aug
2013
Sep
2013
Oct
2013
Nov
2013
Dec
2013
Jan
2014
Feb
2014
Mar
2014
Apr
2014
May
2014
Jun 2013-
May 2014
Chuuk11.6611.9812.8611.7111.5110.6111.2510.107.258.3212.4711.30136.77
Guam NAS6.1810.1414.7412.6611.447.385.114.013.032.072.533.4099.09
Kapingamarangi13.7814.158.139.938.199.279.849.159.2711.4313.6412.08145.85
Koror17.4818.5313.5011.7711.8411.3911.1610.188.567.447.3211.83152.90
Kosrae14.6414.9114.2214.2210.9413.8316.1116.6712.9316.0617.5117.75213.87
Kwajalein6.939.879.7410.7411.1811.286.663.162.642.355.266.7290.41
Lukonor11.6515.9314.0410.1511.329.0811.278.418.939.2611.3111.69151.36
Majuro11.0111.1711.6911.1712.7313.4411.397.746.886.589.4210.11125.25
Pago Pago5.335.555.386.539.2610.1412.8413.3412.0010.689.399.66125.57
Pohnpei14.8115.4314.2612.5515.2714.8316.0813.189.5513.1718.4119.96182.36
Saipan3.628.9113.1310.0910.625.613.852.532.591.892.632.3870.25
Yap12.0415.0814.8213.5012.188.838.516.395.194.565.637.85120.31

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 Climatic Data Center, State of the Climate: Drought for May 2014, published online June 2014, retrieved on September 2, 2014 from http://www.ncdc.noaa.gov/sotc/drought/2014/5.