The next storm system will impact the Mid-Atlantic states beginning overnight Saturday continuing through much of the day on Sunday. The image below (courtesy Pivotal Weather) is from the latest European Forecast Model depicting a strong low pressure system tracking northeast from the Tennessee Valley to Southern New England. Bottom Line: A period of very heavy rainfall with widespread embedded thunderstorms could drop enough rain over a short period of time on Sunday morning to produce flooding of creeks, streams and and urban areas that are low-lying with poor drainage.
Timing the Strongest Thunderstorms
The latest North American Model (next image courtesy Tropical Tidbits) is forecasting widespread thunderstorms to move across the Washington Region from south to north between 10z (6am) and 17z (1pm). The exact time frame of heaviest rain/storms may change a bit with future forecast model updates.