U.S. Drought Monitor Update for March 24, 2020

According to the March 24, 2020, U.S. Drought Monitor, moderate to exceptional drought covers 9.9% of the United States including Puerto Rico, a decrease from last week’s 10.5%. The worst drought categories (extreme to exceptional drought) decreased from 0.5% last week to 0.3% this week. 

The atmospheric circulation consisted of three main parts. The first part was a strong upper-level ridge over the eastern North Pacific that funneled warmer- and drier-than-normal air over Alaska. The second part was a deep trough of low pressure over the western contiguous United States. Pacific weather systems were pushed southward into the trough. They circled around in the trough and eventually moved eastward across the Southwest, where they brought above-normal precipitation and cooler-than-normal temperatures. The Pacific Northwest to northern Plains were drier than normal beneath the resulting northerly upper-level flow. The third part of the atmospheric circulation was a strong ridge of high pressure centered over the Gulf of Mexico that also extended along the East Coast. The ridge kept temperatures warmer than normal from Texas to the Northeast and precipitation below normal across the coastal Southeast. 

Pacific weather systems that moved out of the Southwest and into the Plains ran into the Gulf of Mexico High. They were pushed northeastward toward the Great Lakes and left wetter-than-normal conditions in their wake from the southern Plains to Great Lakes and Northeast. As a result of this pattern, drought or abnormal dryness contracted in parts of the West but expanded in other parts of the West, contracted in parts of Texas, and expanded in parts of the coastal Southeast. 

Abnormal dryness and drought are currently affecting over 79 million people across the United States including Puerto Rico—about 25.6% of the population.