National Drought Monitor for June 17, 2014
Summary
During the drought-monitoring period, widespread, locally heavy downpours brought drought relief to the Midwest, central Plains, and southern Florida, while drought conditions prevailed or intensified from California into the central and southern Rockies.
Alaska, Hawaii, and Puerto Rico
There were no changes made to the drought depiction in Alaska, Hawaii, and Puerto Rico this week. In Alaska, cool, showery conditions were noted across western and southern portions of the state, though low streamflows continued to reflect the impacts of a drier-than-normal spring. In Hawaii, most of the Abnormally Dry (D0) and Moderate Drought (D1) areas received little – if any – rain. Likewise, Puerto Rico’s D0 areas were also dry during the monitoring period, with streamflows dropping below the 10th percentile, indicating the island may slip further into D0 or perhaps even D1 should rain not materialize in the upcoming weeks.
Central Plains
Conditions remained largely unchanged on the central High Plains during the monitoring period, as hot weather (readings as high as 100°F) offset the light to moderate showers (0.1 to 1 inch) which dotted western portions of the region. Farther east, however, locally heavy downpours – with totals averaging 1 to nearly 4 inches – resulted in reduction of Severe (D2) and Extreme (D3) Drought in central and southern Kansas. In improved areas, precipitation over the past 30 days has averaged 150 to 240 percent of normal. The improved conditions are noted in the June 15, USDA-NASS crop condition report for Kansas: winter wheat, which is beyond benefiting from rainfall, was rated 63 percent poor to very poor, while corn was only 9 percent poor to very poor (and 50 percent good to excellent).
Delta
Moderate to heavy showers (1-2 inches, locally more) eased Moderate (D1) and Severe (D2) Drought in southwestern Louisiana, though 90-day rainfall remained well below normal (50-65 percent) in the small area of D1 and D2. The rest of the Delta remained free of drought.
Mid-Atlantic and Northeast
The northeastern quarter of the nation remained free of drought, with widespread showers offsetting increasing heat. Pockets of Abnormal Dryness (D0) are still noted in New England, where despite light to moderate showers (locally more than an inch) over the 7-day period, 30-day rainfall has tallied 35 to 65 percent of normal. Meanwhile, locally heavy showers (2 inches or more) eased D0 in southern West Virginia.
Midwest
Heavy to excessive rainfall eradicated drought but submerged low-lying fields and caused historic river flooding in western portions of the region. Persistent, repetitive showers and thunderstorms – also known as “training” – inundated areas from eastern Nebraska and southeastern South Dakota into southern Minnesota and northern Iowa with 3 to 8 inches of rainfall; these amounts may be conservative, with radar-derived estimates as high as 12 inches. Rain of this magnitude was more than sufficient to warrant a rare, but not unheard of, 2-category improvement, eliminating Moderate Drought (D1) and Abnormal Dryness (D0) from the hardest-hit locales. It should be noted, however, that despite the heavy downpours, long-term precipitation deficits linger (less than 70 percent of normal over the past 12 months) in west-central Iowa; consequently, a small area of D0 (with a Long Term, or “L” designation) remained where shortfalls are most pronounced.
Ohio Valley and Southeast
Widespread showers from the Ohio Valley to the Atlantic and Gulf Coast States were sufficient to prevent much expansion of Abnormal Dryness (D0) or Moderate Drought (D1). However, dry conditions persisted in northeastern Tennessee, where D1 was expanded to reflect 90-day rainfall as low as 60 percent of normal and resultant declining streamflows. Localized soil moisture shortages are noted in the Carolinas, though at this juncture none of the areas of dryness warranted D0. In Florida, 2 to 4 inches of rain signaled the onset of the summer rainy season, alleviating Moderate Drought and reducing the areal extent of D0 in southern portions of the state.
Southern Plains and Texas
Despite temperatures in the 90s, rainfall during the week was sufficient to warrant some modest reductions in drought from northern and central Oklahoma southward into central Texas, while hot, mostly dry conditions in western and northeastern portions of Texas led to small increases in drought intensity. Showers and thunderstorms dropped 1 to locally more than 2 inches of rain across much of central and northeastern Oklahoma, which – while not nearly enough to warrant widespread drought reduction or removal – were enough to improve pastures and summer crop prospects. In Texas, similar amounts of rainfall were reported from Lubbock southeast toward Waco and southward into Austin and San Antonio. Consequently, reductions in drought intensity were made in areas where the heaviest rain fell, although long-term impacts continue (i.e. reservoir storage and ground water supplies) despite recent 60-day surpluses. Rain largely bypassed the Dallas-Fort Worth metro area, where 90-day rainfall averaged 35 to 55 percent of normal at the end of the period; Severe (D2) to Extreme (D3) drought was increased to reflect the deteriorating conditions. Likewise, temperatures approaching or exceeding 100°F (locally as high as 108°F) in Texas’ Trans-Pecos region coupled with 6-month deficits approaching or exceeding 3 inches (locally less than 20 percent of normal) led to increases in Moderate Drought (D1) in western-most portions of the state.
Western U.S.
Unsettled conditions in the north contrasted with ongoing or intensifying drought elsewhere. The lingering benefits of February and early-March precipitation continued to diminish across California and the Southwest as unseasonable warmth and dryness increased water demands and further depleted already-meager snowpacks.
In northern portions of the region, a slow-moving Pacific storm triggered increasingly heavy rain and mountain snow from the Cascades into the northern Rockies, the latter of which was hit with heavy snow at elevations as low as 6,500 feet. In the Northwest’s Moderate (D1) to Severe (D2) Drought areas, however, rain was mostly light (less than half an inch) and insufficient to warrant any reductions in drought intensity and coverage. To further illustrate the drought’s impacts, the USDA-NASS reported Washington’s winter wheat as 26 percent poor to very poor as of June 15, with only 30 percent rated good to excellent.
Farther south, a disappointing water year drew to a close, most likely locking portions of the region into a third consecutive year of drought. In northern and central California, Exceptional Drought (D4) was increased to account for the updated (and mostly final) 2013-14 Water Year precipitation totals; from northern portions of the Coastal Range to Mt. Shasta, precipitation since October 1 totaled 30 to 50 percent of normal (deficits of 16 to 32 inches). The corresponding Standardized Precipitation Indices (SPI), which helps quantify precipitation in terms of drought and historical probability, are well into the D4 category. Feedback from local experts as well as updated precipitation data covering the past 2 to 3 years indicated that D4 expansion was warranted across north-central portions of the San Joaquin Valley and environs as well as from Pyramid Lake in western Nevada northwestward into California; water-year precipitation in both of these areas near or less than half of normal (locally less than 40 percent of normal) . Assessments of the situation in California over the ensuing weeks may warrant additional increases in drought coverage and intensity.
In the central Rockies and Four Corners, changes to this week’s drought depiction were confined to northern and eastern portions of the region. In south-central Wyoming, Abnormal Dryness (D0) was expanded to reflect 180-day precipitation less than 35 percent of normal. In southeastern Colorado, similar precipitation shortfalls and resultant soil moisture deficits led to a small expansion between Pueblo and the New Mexico border.
Looking Ahead
Hot, humid conditions along with scattered afternoon and evening showers and thunderstorms will persist from the central and southern Plains to the Atlantic Coast, while dry weather prevails from California into the Southwest. The best chance for moderate to heavy rain appears to be from northern Texas northward into the Great Lakes, with additional heavy downpours possible in some of the already-flooded areas of the western Corn Belt. Farther south, seasonal showers will persist in Florida, while spotty showers in the interior Southeast may afford localized relief from developing dryness. Out west, rain and mountain snow will diminish in northern portions of the region, while dry, cooler-than-normal weather lingers for much of the period from California into the Four Corners. The NWS 6- to 10-day outlook for June 24-28 calls for above-normal rainfall in the Northwest and from the southern Plains to the central Atlantic Coast. Conversely, drier-than-normal conditions will prevail from northern California into the Four Corners and from the northern Plains into the Upper Midwest. Temperatures are expected to average above normal across much of the contiguous U.S., with cooler-than-normal weather confined to east-central Plains.
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