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Drought Intensifies and May Last Through October

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Drought conditions intensified in parts of the Midwest and Great Plains during the week ending on July 31, and a new forecast calls for the drought to persist straight on through until October. Beneficial rainfall did trim the edges of the drought area slightly during the past week, and may alleviate the drought in some spots during the next several months, according to the new edition of the U.S. Drought Monitor and Seasonal Drought Outlook, both of which were released Thursday morning.

The U.S. Drought Monitor released on August 2, 2012.
Credit: USDA/NOAA.

As of July 31, 62.91 percent of the lower 48 states was in at least moderate drought, down from 63.86 percent on July 24. However, there was a slight increase in the portion of the country suffering from “exceptional” drought, the worst drought category, which rose to 3 percent from about 2 percent on July 24.

“It’s hard to believe that it’s getting worse, but it is, even with some rain in the region,” said Brian Fuchs, a climatologist with the National Drought Mitigation Center at the University of Nebraska-Lincoln.

The drought is the worst to strike the U.S. since at least 1956, and is comparable in terms of its extent to the Dust Bowl droughts of the 1930s and has impacted food prices across the U.S.

On Wednesday, Agriculture Secretary Tom Vilsack added 218 more counties in 12 states to the list of primary natural disaster areas "due to damage and losses caused by drought and excessive heat," a USDA press release said. Those counties are in Arkansas, Georgia, Iowa, Illinois, Indiana, Kansas, Mississippi, Nebraska, Oklahoma, South Dakota, Tennessee, and Wyoming. That brings the total number of counties in the drought disaster area to 1,452 across more than two dozen states, which is slightly more than half of all U.S. counties.

The states where drought continued to intensify included Arkansas, Kansas, Missouri, Nebraska, and Oklahoma. All of these states experienced “devastatingly hot weather” during the past week, with numerous high temperature records set, according to the latest edition of the Weekly Weather and Crop Bulletin, published by the USDA. For example, North Platte, Neb., experienced its second-longest streak of triple-digit heat, with eight straight days from July 17-24, which was second only to a streak of 13 such days in 1934. Des Moines, Iowa, had four straight days with triple-digit heat from July 22-25, including a high of 106°F on July 25. And Oklahoma City had its second-warmest temperature on record, with a high of 112°F, on August 1.

Rainfall departure from average for during July 2012, showing the lack of rainfall in the Midwest and High Plains. Click on the image for a larger version.
Credit: NOAA.

The heat has both aggravated the drought and fed off of it by drying soils and vegetation more rapidly, which helps temperatures rise even more. This feedback was observed during the Texas drought of 2011, and studies show that manmade global warming may be making droughts hotter than they otherwise would be, even if natural climate variability, such as La Nina, helped trigger the drought conditions in the first place.

Some rains fell during the past week in the Southwest and the northern corn belt of the Upper Midwest, which helped alleviate the drought conditions somewhat, along with the Southwest and eastern U.S., but the rainfall was largely scattered in nature.

The High Plains, which has been roasting under a large "heat dome" of High Pressure for much of the summer, has been the hardest-hit drought region, with nearly 50 percent of a six-state area from Colorado to South Dakota experiencing extreme to exceptional drought. 

As for the title of hardest-hit state, Arkansas is vying with Kansas for that dubious distinction. In Arkansas, 44 percent of the state is experiencing exceptional drought conditions, with about 81 percent classified as being in extreme-to-exceptional drought. That was a jump from July 24, when about 34 percent of the state was in exceptional drought.

In Kansas, 88 percent of the state is in extreme to exceptional drought, up from about 73 percent a week ago. Demonstrating how quickly the drought evolved, just 0.3 percent of the state was in extreme-to-exceptional drought as of May 1.

The latest Seasonal Drought Outlook shows that the drought is expected to persist across the country through October, but relief is forecast for parts of the East, Southeast, and Southwest. An active southwestern monsoon season, which has been bringing nearly daily thunderstorms to Arizona, Colorado, and New Mexico, is the main reason why drought is forecast to improve in those regions.

The Drought Outlook paints an ominous picture for the High Plains and Midwest, however. "It would require a dramatic shift in the weather pattern to provide significant relief to this drought, and most tools and models do not forecast this," said the Climate Prediction Center.

And in Texas, which was struck by its most intense and costly one-year drought on record last year — which caused billions in damage — drought conditions are projected to expand by October. The drought is also projected to expand across the Dakotas and Montana.

 

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