Thu Aug 2, 2012, 08:46 AM
hatrack (37,065 posts)
7/31 Monitor; Conditions "Set Drought Apart From Anything We Have Seen At This Scale For Decades"
National Drought Summary -- July 31, 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/.
The Northeast and Mid-Atlantic: Short-term dryness led to an introduction of D0 in eastern and northern Maine. Vermont, New Hampshire and eastern New York also shared in a slight reduction of D0 compared to last week. Moderate rains across a good portion of Pennsylvania led to 1-category improvements and this trend continued down into parts of northwestern Maryland, West Virginia and western Virginia. In the Carolinas, favorable rains improved the D1 along coastal South Carolina and led to a reduction of D0 in eastern North Carolina as well. Low streamflows and ground water levels have led to a slight expansion of D2 in the Delmarva Peninsula.
The Southeast: Good rains (3 to 5 inches) fell across most of Tennessee, and parts of central Alabama also shared in good rains last week, leading to widespread 1-category improvements this week. Alabama continues to be affected by the long-term nature of multi-year D2-D3 entrenched across the eastern half of the state. This pattern continues across the border into Georgia, which has not seen much rainfall of late either, leading to an expansion of D3 and D4 in north-central and northwestern locales.
The Midwest: Most of the region registered above-normal temperatures for the period ending Tuesday morning. In fact, preliminary data show that July came in at 5-10 degrees above normal for the month of July. The region continues to be impacted not only by oppressive heat, but also by depleted soil moisture, desiccated pastures and widespread crop damages, livestock culling and elevated fire risk. Recent concerns have now turned to soybeans and water supply as the droughtís duration persists. Some fared a bit better than others; southern Minnesota and southern and eastern Wisconsin benefitted the most from rains, leading to general 1-category improvements this week. Rains also fell across northern Indiana and southern Michigan, leaving things pretty much unchanged from last week. That said, there is a slight expansion of D3/D4 across western and central Indiana. Much of southern Ohio and eastern Kentucky also saw measurable improvement on the order of 1-category this week, pushing the drought to the west. Longer-term impacts still remain even given the short-term relief, but parts of eastern Kentucky and Ohio are seeing a rebound in streamflows, which is a good sign. In the western half of the region, things continue to worsen across Missouri and Arkansas, with continued deterioration and encroachment of D3 and even D4.
The Great Plains: Expansion is noted across most of the region this week as abnormally hot temperatures (5 to 10 degrees above normal) continue to plague the region, bringing stress to pastures, crops, livestock/wildlife, trees and humans alike. Rainfall during the last week was confined to small patches in the Black Hills and northeastern South Dakota and southeastern North Dakota. Those areas receiving the 2- to 3-inch rains were improved 1-category in the Dakotas. The same canít be said to the rest of the region as D1-D3 continue to advance across more of eastern Nebraska, southeastern South Dakota, Kansas, Oklahoma and the Texas Panhandle. In Kansas and the Panhandles of Oklahoma and Texas, D4 has also expanded, given the intense conditions and extreme impacts being observed. These areas canít seem to shake off last yearís drought and have now been dragged back into it this year, with the exception being southeastern Texas, which has continued to see a much more favorable wet pattern the past several months.
In addition to the large geographic footprint of this yearís drought, the quick onset and rapid ramping up of intensity, coupled with extreme temperatures and subsequent impacts, has really left an imprint on those affected and has set this drought apart from anything we have seen at this scale over the past several decades.
The West: The West remains relatively quiet in most parts, with the West Coast benefitting from below-normal temperatures last week as well. Warmer temperatures continue to plague the Rockies and Front Range while precipitation was mostly confined to Arizona and Colorado, where monsoon rains continue to bring relief. Changes this week on the map are marked by 1-category improvement (from D3 to D2) in north-central and southwestern Colorado as well as eastern Utah. The same canít be said for southeastern Colorado, where D3 has now expanded to cover this region as well as northeastern New Mexico, western Kansas and the Oklahoma Panhandle. To the north, Montana has seen recent dryness as well, leading to a slight expansion of D0 across the northern tier counties.
Hawaii, Alaska and Puerto Rico: Most of the islands continue with the status quo this week, but deterioration is noted on both Kauai and Molokai this week, where lowland dryness continues to hinder pasture growth and is hampering livestock operations.
Alaska and Puerto Rico remain unchanged this week.
Looking Ahead: The 5-day forecast (August 1-6) calls for a mixed bag of potential, with the best chances of precipitation being located over western Colorado, the northern and Central Plains (including northwestern Minnesota), parts of the Upper Midwest, the Northeast and the Southeast. Temperatures are expected to be above normal in the Pacific Northwest, Northeast, and Southern Plains while the Northern Plains may come in a bit cooler than normal.
For the period August 7-11, a continuation of the recent pattern is expected to persist with above-normal temperatures dominating most of the country, the areas of exception being the West Coast and Florida. Below-normal precipitation appears likely in the southern and east-central Plains spreading into Missouri and northern Arkansas. Those areas projected to see a greater likelihood of precipitation are the Four Corners, Upper Great Lakes, Gulf Coast, Atlantic Seaboard and the northern tier states in the Northeast from New York to Maine.
Author: Mark Svoboda, National Drought Mitigation Center
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 August 1, 2012
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