US Drought Monitor - August 7, 2012

Larger Image Link: http://droughtmonitor.unl.edu/ National Drought Summary -- August 7, 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: Rainfall over the past week was scattered and temperatures were above normal for most locales. As such, most of this area stays status quo this week. Minor adjustments of note include some reduction of D0 and D1 in West Virginia, Virginia and North Carolina, where some locales saw 3 to 5 inches this past week. Low streamflow and groundwater levels remain a concern heading into fall for parts of Virginia, Maryland, Delaware and northern Maine. The Southeast: Parts of the Southeast received a good soaking last week while others missed out, leading to a mixed bag of changes on this week’s map. The heaviest precipitation fell over eastern Tennessee, the western Carolinas, northern Georgia, eastern Alabama and the Florida Panhandle, leading to 1-category improvements along the drought’s perimeter in these regions. This hasn’t removed drought, but instead has only tightened the gradients between the haves and the have-nots, as conditions can vary wildly over very short distances. The underlying hydrologic drought in Georgia and Alabama remains well seated, with low streamflows being commonplace as they are well into a two-year drought. The Midwest: Conditions continue to improve in the eastern half of the region as another week of good rains came to parts of Ohio, Indiana and Kentucky. Again, generally speaking, the drought continues to improve and is being pushed west, tightening the gradient along the way with 1-category improvements noted in eastern and southern Ohio, eastern and central Kentucky and north-central Indiana. Parts of the core region of drought in this region continue to see deterioration this week marked by a slight expansion of D2/D3 in southeastern Indiana. Continuing east, both Iowa and Illinois see expansion of D3 and D3. Missouri and Arkansas continue to worsen as the heat and dryness continues its grip, leading to an expansion of D4 in northern Arkansas and southern Missouri along with a new area of D4 in extreme west-central Missouri adjoining Kansas. Reports of water-related impacts are ticking upward with each passing week as mandatory restrictions continue to ramp upward around the region. As the drought continues, this will undoubtedly become a more prevalent issue as the agricultural season passes and attention turns to next year’s crops or herds. The Great Plains and South: Same song, tenth verse last week as much of the Plains saw the pattern of excessive heat and dryness persist, leading to more expansion across Nebraska, Kansas, Oklahoma and parts of Texas. As a result, D3 has moved across east central Nebraska and into west central Iowa, D3 pushes more to the northeast in Kansas, and D4 expands in western Kansas and connects up with a growing area of D4 in western Oklahoma. In addition, water emergencies and shortage concerns in several communities result in a new D4 region in east central Kansas over into extreme west central Missouri. The only real area of improvement noted this week is in the Black Hills region of South Dakota, where generally cooler weather and recovering streamflows lead to a small improvement from D3 to D2, which extends into extreme northeastern Wyoming. After some improvement of late, the heat and dryness bring the return of a bit more D0-D3 into the Panhandle and western reaches of Texas. The other change of note this week lies in northern Louisiana after a recent dry spell led to a slight southward push of D0 and D1 there. The West: The West saw a mixed bag of results over the past week with the monsoon rains bringing relief to some and nothing much to many others. A slight expansion of D1 this week is noted in Montana on the heels of an expansion of D0 northward to the Canadian border last week. Most of Colorado remains unchanged this week but the heat and dryness does lead to a joining of the D4 between east central CO and western Kansas. The D3 also extends out of southeast Colorado and the Oklahoma Panhandle into more of northeastern New Mexico along with a slight push westward of the D2 in north central New Mexico this week. Northwestern New Mexico has benefitted from a good start to the monsoon, leading to a reduction of D2 and D3 in the northwestern part of the state into the eastern edge of the Navajo Nation lands. Longer-term conditions and impacts in the Navajo Nation have led to a state of emergency Executive Proclamation due to the extreme conditions on their lands in the Four Corner region. Hawaii, Alaska and Puerto Rico: Conditions remain unchanged on this week’s map for Hawaii, Alaska and Puerto Rico. Looking Ahead: The 5-day forecast (August 8-12) shows a shift in the heat from the country’s mid-section to the West as high pressure builds in there. This leaves prospects for precipitation high and dry for most locations west of the Rockies and increases the chances for the wet stuff over the Midwest, Northeast, Great Lakes, Gulf Coast and Atlantic coastal reaches of the Carolinas and Georgia. Above-normal temperatures will accompany the high pressure in the West and the cool down to the east of the Rockies will be a welcomed respite for most of the Great Plains and Midwest. For the period August 13-17, above-normal temperatures are more likely across Alaska, the Southwest, Great Basin, southern Rockies and southern Plains. Interestingly, no regions are forecasted to see below-normal temperatures during this period. The chances for below-normal precipitation are greatest in eastern and central Alaska, the southern Plains and lower Midwest while the odds of above-normal rains are best situated over the Southwest, northern Plains and eastern Montana as well as along the Gulf Coast and Atlantic Coast from Florida northward to Virginia. Author: Mark Svoboda, National Drought Mitigation Center 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 August 8, 2012