Weather Summary: Highly beneficial rainfall brought additional drought relief to the south-central United States and began to chip away at short-term precipitation deficits in the mid-Atlantic and Northeastern States. Parts of the Southeast also experienced drought relief, but little rain fell in a core drought area centered on central and southern Georgia and northern Florida. In the Midwest, a dry week followed early-May rainfall. Dry conditions also prevailed across much of the West.
The East: Much-needed rain put a significant dent in short-term dryness (D0) and moderate to severe drought (D1 and D2) across the mid-Atlantic and Northeastern States. In fact, rain eradicated nearly all of the D2 in the northern Atlantic coastal plain. Farther south, rain provided drought relief in many areas, especially from parts of Alabama into northern Georgia and the Carolinas. Some of the most widespread heavy rain affected North Carolina, where totals of at least 4 to 6 inches were common across the central one-third of the state. Meanwhile, only light showers dotted the core area of extreme to exceptional drought (D3 to D4) across the lower Southeast. For the year ending May 15, 2012, Augusta, Georgia, received only 22.44 inches of rain. The previous driest such period on record occurred a year ago, from May 16, 2010 – May 15, 2011, when 29.72 inches fell. At times, early-season heat has aggravated drought conditions in the lower Southeast. For example, recent daily-record highs in Florida included 95°F (on May 11) in Ft. Myers and 94°F (on May 12) in Sarasota-Bradenton.
The Mid-South: “Flash drought” conditions began to develop in an area centered on the lower Ohio Valley and the northernmost portion of the Mississippi Delta. The term “flash drought” refers to acute short-term dryness, often aggravated by above-normal temperatures. A decline in crop conditions has been noted across the Mid-South, with 10% of the Arkansas rice crop rated in very poor to poor condition by May 13, according to USDA. Some of the most significant drought was noted across western Kentucky, where severe drought (D2) expanded. Drought also began to creep northward into southern Illinois.
The Midwest: Mostly dry weather returned, following a period of beneficial rainfall in late April and early May. There were only minor changes to the depiction of dryness (D0) and moderate drought (D1). A core area of dryness and drought still existed across the upper Midwest, including most of Minnesota and northern Iowa.
The Plains: Much of Texas, except northern areas, experienced substantial drought relief. Widespread 2- to 4-inch totals were noted across southern and western Texas, primarily from May 10-12, allowing for a broad improvement in the drought depiction. In the vicinity of Houston, Texas, May 11-12 totals included 9.83 inches at Sugar Land and 6.23 inches at Hobby Airport. Despite some rainfall on the southern High Plains, winter wheat continues to struggle, with 39% of the Texas crop rated in very poor to poor condition on May 13. Farther north, some modest expansion of dryness (D0) was observed across the northern and central Plains, as a relatively wet April was followed by a rather dry first half of May.
The West: Parts of southern and eastern New Mexico received widespread, locally heavy precipitation, but dry weather covered the remainder of the West. The drought impact type was changed to long term (L) across southern New Mexico, where substantial rain fell. Elsewhere, relatively minor changes were highlighted by a modest expansion of severe drought (D2) in northwestern Arizona and southern Nevada, and a slight expansion of severe drought in north-central Colorado.
Hawaii, Alaska and Puerto Rico: Currently, there is neither dryness nor drought depicted in Alaska and Puerto. The drought situation in Hawaii remained virtually unchanged, except for the expansion of severe drought (D2) on the southern portion of the Big Island due to deteriorating pasture conditions, and the removal of some lingering dryness (D0) from eastern Oahu.
Looking Ahead: During the next 5 days (May 17-21), periods of rain will continue to provide drought relief in the southern Atlantic States, particularly across Florida’s peninsula. In Florida, 5-day rainfall totals could reach 1 to 3 inches, with locally higher amounts. Meanwhile, generally light to moderately heavy showers will spread across the northern and central Plains and the upper Midwest, although most totals will be less than an inch. Elsewhere, mostly dry weather can be expected through May 21 from southern California to the southern Plains, and from the Mid-South into the Ohio Valley. The NWS 6- to 10-day outlook for May 22-26 calls for near- to above-normal temperatures nationwide, except for cooler-than-normal conditions in Florida and the Northwest. Meanwhile, below-normal rainfall in the Northeast and from California to the central and southern Plains will contrast with wetter-than-normal weather along the southern Atlantic Coast and across the nation’s northern tier from the Pacific Northwest to Minnesota.
Author: Brad Rippey, U.S. Department of Agriculture
D0 ... Abnormally Dry ... used for areas showing dryness but not yet in drought, or for areas recovering from drought.
Drought Intensity Categories
D1 ... Moderate Drought
D2 ... Severe Drought
D3 ... Extreme Drought
D4 ... Exceptional Drought
Drought or Dryness Types
S ... Short-Term, typically <6 months (e.g. agricultural, grasslands)
L ... Long-Term, typically >6 months (e.g. hydrology, ecology)