The upper-level low pressure system that has been stalled across the Tennessee Valley will finally begin to move northeastward crossing the DC region on Saturday morning before exiting on Saturday night.
Window for Steadiest Rainfall
A period of moderate to heavy rain is expected late Thursday night and continuing into Friday morning across the Washington Area. The latest North American Model (image courtesy Pivotal Weather) below shows the heavy rain bands moving into the DC Area on Friday morning and moving north of our area during the afternoon. Scattered thunderstorms may break out on Friday afternoon as the area of low pressure approaches, increasing the lapse rates in the atmosphere. Some thunderstorms on Friday afternoon will be capable of producing small hail.
The heaviest rainfall is expected across the eastern slopes of the Blue Ridge Mountains where one to three inches of rain is possible.