Drought Reinforcing Drought in the U.S. Southern Plains

It’s a discouraging fact that drought reinforces drought, especially in the summer. When it doesn’t rain, the ground and plants dry out. With less water to evaporate during the long days of summer heat, the landscape gets still hotter. Hotter temperatures accelerate evaporation, drying everything out further. It can be a tough cycle to break.

A drought-causing-drought feedback loop is solidly underway across much of the United States, especially in the Southern Plains. The maps above show the drought status in the heart of the country on August 7 (left) and August 14 (right). Conditions range from “abnormally dry” (yellow) to “exceptional drought” (reddish brown).

Over the span of a week, a patch of exceptional drought in parts of Colorado, Kansas, and Oklahoma merged with another patch of exceptional drought that extended from parts of the lower Mississippi River into the Ohio Valley. The area affected by exceptional drought also expanded in Nebraska and Georgia, and extreme drought expanded in New Mexico and southern Texas. A few of the region’s northern and eastern states experienced some lessening of the severity of their drought, including parts of Ohio, Indiana, and Michigan.

For the contiguous United States as a whole, about 62 percent of the country was in some state of drought, with another 16 percent ranking as “abnormally dry.” The area hit by the worst drought increased from a little over 4% to a little over 6%.

Links

U.S. Drought Monitor

U.S. Drought Portal

State of the Climate: National Drought Analysis for July 2012