This Week’s Drought Summary
An upper-level ridge dominated the central contiguous U.S. (CONUS) during this U.S. Drought Monitor (USDM) week (September 14-20). It was bracketed by an upper-level trough which moved out of the Northeast early in the week, and a Pacific upper-level trough that moved into the West as the week progressed. Pacific weather systems moved across the northern states between the troughs. This pattern resulted in above-normal precipitation across much of the West and parts of the Northeast. Fronts associated with the Pacific systems triggered showers and thunderstorms across parts of the central and northern Plains to Mid and Upper Mississippi Valley. For the rest of the CONUS, a large dry air mass covered much of the southern Plains and East throughout the week. Rain occurred along a stationary front draped across Florida that was associated with the southern edge of the air mass, but for much of the South, Southeast, Mid-Atlantic, and Midwest regions it was a dry week. Temperatures averaged warmer than normal across the Plains to Great Lakes, and cooler than normal across much of the West, Southeast, and northern New England. A tropical system brought heavy rain to Puerto Rico and the Virgin Islands. Drought or abnormal dryness expanded or intensified across northern parts of the West, from the central and northern Plains to the Mid- and Upper Mississippi Valley, and over parts of the Mid-Atlantic coast. Drought or abnormal dryness contracted where it rained, especially in parts of Florida, New Mexico, and the Northeast, in a swath from Iowa to Illinois, and across Puerto Rico.
South
A few areas of the Gulf Coast and western Texas received up to half an inch of rain this week, but the South region was, for the most part, dry with no rain falling. Moderate and severe drought contracted slightly in a couple spots in southern Texas, and abnormal dryness and moderate drought expanded in a couple other areas of the Lone Star State and abnormal dryness expanded in Tennessee. But the biggest changes occurred in Oklahoma and Arkansas. D1-D4 expanded in Oklahoma and D0-D2 expanded in Arkansas. Soils continue to dry and groundwater and stream levels are low. According to U.S. Department of Agriculture (USDA) statistics, 82% of Oklahoma’s topsoil moisture is short to very short of moisture (dry to very dry). The only drier years in mid-September in data going back to 2010 were 2011 and 2012, which were very bad drought years. All states in the region except Louisiana and Mississippi had half or more of the topsoil moisture short or very short of moisture. Almost 70% of the pasture and rangeland in Oklahoma was in poor to very poor condition. Ponds in Oklahoma are drying up and 63% of the cotton crop is in poor to very poor condition.