U.S. Drought Monitor Update for October 6, 2020

According to the October 6, 2020, U.S. Drought Monitor, moderate to exceptional drought covers 37.2% of the United States including Puerto Rico, an increase from last week’s 35.8%. The worst drought categories (extreme to exceptional drought) increased from 12.2% last week to 13.3% this week. 

Atmospheric circulation this week was dominated by a high-pressure ridge over the western contiguous United States and a low-pressure trough over the East. This classic pattern  deflected Pacific storm systems  into western Canada, leaving the western contiguous United States with sunny, dry, and warmer-than-normal weather. The western ridge and eastern trough produced a northwesterly flow over central North America. This flow pattern funneled cooler- and drier-than-normal air into the contiguous United States east of the Rockies. 

As they moved south and  east, the cold fronts tapped Atlantic moisture to generate precipitation over the Great Lakes to the East Coast, but most of the rest of the contiguous United States was drier than normal with little to no precipitation falling. As a result, drought  and abnormal dryness expanded in most vulnerable areas. There was some contraction in the Northeast and Midwest, but expansion dominated in the West, Plains, Midwest, and Northeast, resulting in an expansion of the overall U.S. drought footprint again this week. 

Abnormal dryness and drought are currently affecting over 120 million people across the United States including Puerto Rico—about 38.7% of the population.