Rainfall totals that created Thursday's flash flooding in D.C. and some of its suburbs

Southwest Monsoon Flooding

Monsoonal conditions in the Southwest will lead to threats of flash flooding through the weekend. Severe thunderstorms will be possible through Friday night in the northern tier of the country and Saturday afternoon in the vicinity of the Southern Great Lakes. Warm conditions have prompted Heat Advisories for portions of the Midwest and ArkLaMiss this weekend. Read More >

Thursday afternoon September 10th 2020

Early on Thursday afternoon, showers and thunderstorms arose along a weak atmospheric boundary oriented north to south across the Washington area. The storms that formed were fed by tropical moisture to our southeast which allowed for heavy rainfall rates. In addition, weak winds in the atmosphere kept the storms moving slowly. That combination of heavy rain and slow movement allowed for 2-5" of rain to fall in a relatively narrow corridor across parts of the Washington metro area. Most of that rain fell within 2 hours.

The heavy rains produced flash flooding of numerous roads and streams and first responders conducted several water rescues. The hardest hit areas were: the District of Columbia, Arlington and Alexandria Virginia, and the Maryland suburbs in Prince Georges and Montgomery Counties.