U.S. Drought Monitor Update for August 3, 2021

According to the August 3, 2021, U.S. Drought Monitor, moderate to exceptional drought covers 40.0% of the United States including Puerto Rico, an increase from last week’s 39.7%. The worst drought categories (extreme to exceptional drought) increased from 21.3% last week to 21.7% this week. 

The atmospheric circulation consisted of a strong ridge of high pressure over the western contiguous U.S. with a low pressure trough building over the East. The ridge deflected Pacific storm systems into western Canada. The systems were directed back into the contiguous United States by the eastern trough, dragging Canadian cool fronts with them into the Plains to Gulf of Mexico coast. 

An active monsoon gave the Southwest above-normal precipitation and cooler-than-normal temperatures, while the western ridge kept the rest of the West warmer and drier than normal. The cool fronts triggered precipitation east of the Rockies, with areas of above-normal precipitation scattered across the Plains, South, Midwest, and Northeast. Other areas in the Plains and Midwest to Appalachians were drier than normal. The fronts gave the Ohio Valley to Northeast a cooler-than-normal week, while temperatures averaged near to warmer than normal in the South.  

Drought and abnormal dryness contracted in parts of the Northeast and Great Lakes, and reduced in intensity in the Southwest, where beneficial rains fell. But drought and abnormal dryness intensified or expanded where little to no rain fell in northern parts of the West, northern Plains to Upper Mississippi Valley, central Plains, central Appalachians, and northern Maine. Overall, expansion slightly exceeded contraction, with the nationwide moderate to exceptional drought area increasing this week.

Abnormal dryness and drought are currently affecting over 94 million people across the United States including Puerto Rico—about 30.2% of the population.