U.S. Drought: Weekly Report for July 23, 2024

According to the July 23, 2024 U.S. Drought Monitor, moderate to exceptional drought covers 17.0% of the United States including Puerto Rico, a decrease from last week’s 17.4%. The worst drought categories (extreme to exceptional drought) slightly decreased from 1.3% last week to 1.2%.

The upper-level circulation pattern over the contiguous U.S. (CONUS) during this U.S. Drought Monitor (USDM) week (July 17–23) changed very little compared to previous weeks. A ridge of high pressure remained anchored over the West, while an upper-level trough of low pressure stretched from the Great Lakes to the Lower Mississippi Valley. A big difference, however, was that the trough kept in place a stationary front that stretched from Texas to New England. The front served as a trigger for persistent showers and thunderstorms that were fed by Gulf-of-Mexico and Atlantic moisture. 

Weekly precipitation was above normal along the front from the southern Plains to the Southeast, in parts of the Northeast, and across the Tennessee Valley to the Mid-Atlantic, where rain was sorely needed. Further west, summer monsoon showers gave parts of the Southwest a wetter-than-normal week, but the western ridge kept most of the West drier than normal. A northerly flow between the ridge and trough directed dry air into the northern Plains and most of the Midwest. The ridge also kept most of the West warmer than normal, with many temperatures reaching into the triple digits. Numerous large wildfires raged across the West, due in part to the hot and dry weather. 

The trough funneled cooler air into the Great Plains and Midwest, where the week averaged cooler than normal, while clouds and showers kept temperatures near to a little cooler than normal across the Deep South and into the Southeast. The North Atlantic ridge was slow to loosen its grip on the East Coast, where temperatures averaged near to warmer than normal. Outside of the CONUS, the western ridge stretched northward across western North America and into Alaska, with most of the state having a warmer- and drier-than-normal week. Puerto Rico and the U.S. Virgin Islands had a mostly warmer-than-normal week with a mixed precipitation anomaly pattern, while a dry and stable air mass strengthened its grip over Hawaii.

Drought or abnormal dryness contracted where heavier rain fell across parts of the Southwest and southern Plains, the Lower Mississippi Valley to the Southeast, and the Mid-Atlantic coast to parts of the Ohio Valley. But the continued dryness and heat expanded or intensified drought or abnormal dryness across much of Hawaii and parts of the West, central to northern Plains, and Ohio Valley to the mid-Appalachians. 

Nationally, contraction was more than expansion, so the nationwide moderate to exceptional drought area percentage decreased this week. Abnormal dryness and drought are currently affecting over 127 million people across the United States including Puerto Rico—about 40.9% of the population.