12/11 Drought Monitor - PNW Better, But Plains Wheat Burning Up; SD 64% P/VP; TX, NE OK - 40-45%

National Drought Summary -- December 11, 2012

The discussion in the Looking Ahead section is simply a description of what the official national guidance from the National Weather Service (NWS) National Centers for Environmental Prediction is depicting for current areas of dryness and drought. The NWS forecast products utilized include the HPC 5-day QPF and 5-day Mean Temperature progs, the 6-10 Day Outlooks of Temperature and Precipitation Probability, and the 8-14 Day Outlooks of Temperature and Precipitation Probability, valid as of late Wednesday afternoon of the USDM release week. The NWS forecast web page used for this section is: http://www.cpc.ncep.noaa.gov/products/forecasts/.

Moderate to heavy precipitation fell on a swath from the lower Mississippi Valley northeastward through the Appalachians and upstate New England. A large part of this region received over an inch of precipitation, with 3 to 5 inches reported in parts of the Ohio and lower Mississippi Valleys, and a few other isolated areas. Farther northwest, moderate precipitation totaled up to 1.0 inch along a strip from the northern High Plains eastward through parts of the Great Lakes region. West of the Plains, heavy precipitation was observed from northern California northward through western Oregon and Washington. A few inches fell on some of the higher elevations, and coastal areas near the Oregon/California border. And finally, precipitation fell on parts of the central and northern Rockies and the northern Intermountain West. Isolated totals up to 4 inches were measured in some of the higher elevations.

The Northeast: Generally 0.5 to locally 2.0 inches fell on the D0 areas, but the precipitation was not enough to change the intensity or coverage of the dry areas substantially.

The South Atlantic Seaboard: Light to moderate precipitation was restricted to areas near the Appalachians and parts of Florida last week. Enough precipitation fell to bring relief to most of the D0 area in southern Florida, with dryness now restricted to a small part of the southwestern coast. In addition, some small areas of improvement were noted in parts of northern Georgia and western South Carolina where moderate precipitation fell. In contrast, little precipitation fell on central and eastern Georgia, allowing for expansion of D2 and D3 areas in parts of those regions, most notably near the Georgia coast.

The Lower Mississippi and Ohio Valleys: Moderate to heavy precipitation through most of this region brought large areas of 1-category improvement from Louisiana, eastern Arkansas, and Mississippi northeastward through southern Ohio, and a portion of central Alabama. Precipitation totals of 3 to 5 inches were fairly common from the central Tennessee/Kentucky border northward to the Ohio River and northeastward into southern Ohio. As a result, dryness and drought retracted westward across this broad area. Precipitation dropped off markedly farther to the north and west, particularly above the Ohio/Mississippi Confluence, so no improvement occurred across these regions.

The Plains: Moderate to heavy precipitation – a few inches in spots – brought improvement to parts of the Texas coastline. Across the northern Plains, generally 0.5 to 1.0 inch fell from portions of the Dakotas eastward across southern Minnesota and western Wisconsin, but any improvement seemed insufficient to make any changes to the Drought Monitor in those areas. Through the remainder of the Plains, little or no precipitation fell. As a result, 1-category deterioration was assessed in parts of Texas, eastern Kansas, and small parts of adjacent areas. The continuing dryness has negatively impacted the winter wheat crop. According to the National Agricultural Statistics Service of the U. S. Department of Agriculture, 64 percent of the crop is in poor or very poor condition in South Dakota, and 40 to 45 percent are poor or very poor in Texas, Oklahoma, and Nebraska.

The West: It was a dry week in eastern sections of Washington and Oregon, and from the central Rockies to the Mexican border. In these areas, dryness and drought remained essentially unchanged. Farther north and West, the precipitation across California, Idaho, Montana, and northwestern Wyoming improved conditions in some of the former D0 to D2 areas there. Among other changes, dryness was pulled out of the Sacramento Valley, and moderate drought (D1) improved in parts of Yellowstone and adjacent areas.

Hawaii, Alaska, and Puerto Rico: Heavy precipitation, generally 2 to 4 inches, fell across Kauai, Hawaii, engendering 1-category improvements island-wide. D0 to D2 conditions are now confined to southern sections of the Island. Less precipitation, if any, fell on the rest of the state, keeping dryness and drought unchanged. Elsewhere, no changes were made to the D0 area in Alaska, and there is no dryness assessed across Puerto Rico.

Looking Ahead: During the next 5 days (December 13 - 17, 2012), moderate to heavy precipitation (0.5 to locally 3.0 inches) is expected from the central Rockies and the Intermountain West westward to the Pacific Coast, from part of the central Plains northeastward through the Great Lakes region, from the central Gulf Coast states northeastward through the central and southern Appalachians, and along the East Coast from Virginia southward through South Carolina and central and northern Georgia. Most locations across the eastern half of the country are forecast to receive at least 0.25 inch of precipitation, with little if any expected in the Florida Peninsula, northern Maine, and the High Plains. For the next 5 days (December 18 – 23, 2012), odds favor above-median precipitation once again from the central Rockies and part of the Intermountain West westward to the Pacific Coast. Wetter than normal weather also seems most likely across the mid-Atlantic, the northern half of the Appalachians, and the Northeast. In contrast, subnormal precipitation is favored across the Southeast, most of the Mississippi Valley and Plains states, and the northern Rockies.

Author: Rich Tinker, Climate Prediction Center/NCEP/NWS/NOAA

Dryness Categories

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)



Updated December 12, 2012