Thursday, July 19, 2012

Drought Update: 42% of U.S. Severe to Exceptional

The percentage of the U.S. affected by abnormally dry/drought conditions increased slightly in the past week to 81%, the highest since at least 2000. Meanwhile, the intensity of the drought increased as the severe and above category (D2-D4) jumped 5 percentage points to 42%, also a new 21st century high. The 2 most intense categories (extreme and exceptional), however, are still well below their peaks of 2011.

From the Drought Monitor report:
A strong upper-level ridge of high pressure dominated the nation’s weather this U.S. Drought Monitor (USDM) week, bringing well above-normal temperatures to the central and northern tier states. Clouds with scattered showers and thunderstorms along a stalled cool front kept temperatures below-normal in the southern states. But even then, maximum temperatures were 90 degrees F or warmer across much of the country, with maximums exceeding 100 from South Dakota to Kansas. Philip, South Dakota, reached 109 degrees on July 15. Beneficial rain fell from southern Texas to the southern Appalachians along the front. Excessive rainfall occurred over southeast Texas where amounts totaled 10 inches or more in places, but elsewhere rainfall amounts were generally localized with limited relief. Monsoon showers and thunderstorms brought above-normal rain to parts of the West, but the rain had little impact on deficits which have accumulated over several months. Weak fronts triggered localized showers and thunderstorms along the northern tier states. In between, hot and dry weather dominated from the central Plains to Ohio Valley, Great Lakes, and Northeast.

Another week of hot and dry weather continued the deterioration of crop conditions in America’s breadbasket. U.S. Department of Agriculture (USDA) reports for the week ending July 15 indicated that 38 percent of the nation’s corn crop was in poor to very poor condition, compared to 30 percent a week ago, and 30 percent of soybeans were in poor to very poor condition (compared to 27 percent last week). Fifty-four percent of the nation’s pasture and rangeland was in poor to very poor condition, which is a jump of 4 percent compared to last week and is an all-time high for the 1995-2012 growing season weekly history. About two dozen large wildfires, mostly in the West, were burning on July 17, about half the number compared to a week ago. Streamflows were in the lower tenth percentile of record, or at record low values at several time scales, across much of the Midwest and parts of the central Plains, West, Southeast, and even parts of New England. As a result, the impacts boundaries were shifted to reflect short-term and long-term drought conditions from the west coast to Ohio Valley and Southeast, with short-term conditions indicated in the northern tier states and from eastern Tennessee to New England. Long-term impacts were indicated for parts of the Southwest and central Gulf of Mexico states.

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