U.S. Drought: Weekly Report for July 18, 2023

According to the July 18, 2023 U.S. Drought Monitor, moderate to exceptional drought covers 21.6% of the United States including Puerto Rico, a decrease from last week’s 22.5%. The worst drought categories (extreme to exceptional drought) stayed about the same as last week’s 2.2%.

A strong ridge of high pressure was anchored across the southwestern U.S. during this U.S. Drought Monitor week (July 12–18). The ridge extended northward across the western contiguous U.S. and into western Canada. It was also part of the subtropical high-pressure belt that extended eastward across the Caribbean and North Atlantic, and westward across the North Pacific. The ridge suppressed precipitation, leaving most of the western contiguous U.S., Texas, and the Caribbean dry. It also brought above-normal temperatures, with sweltering record heat occurring in the Southwest and southern Plains. 

Further north, Pacific weather systems moved in the jet-stream flow along the U.S.-Canadian border. Cold fronts and surface low-pressure systems that were associated with the weather systems weakened as they penetrated the western ridge. They were rejuvenated as they moved into an upper-level trough over eastern North America, which provided more favorable conditions. The fronts brought cooler-than-normal air to the northern and central Plains and Upper Midwest, and they moderated temperatures as they worked their way into the Southeast. They also tapped Gulf of Mexico and Atlantic moisture to generate showers and thunderstorms that gave parts of the Plains, Midwest, and East and Gulf coasts above-normal precipitation for the week. Some of the thunderstorms produced locally heavy rains. 

Drought or abnormal dryness contracted or was reduced in intensity in areas that were wetter than normal, especially in eastern parts of the central Plains, and parts of the Mississippi and Ohio Valleys, southern Great Lakes, and Northeast. But drought or abnormal dryness expanded or intensified where it continued to dry, especially across parts of the Southwest, southern Plains, and Upper Mississippi Valley. 

Nationally, contraction exceeded expansion, so the nationwide moderate to exceptional drought area decreased this week. Abnormal dryness and drought are currently affecting over 145 million people across the United States including Puerto Rico—about 46.7% of the population.