What to KnowA FIRST ALERT for heavy rain and severe storms is in effect from 1 p.m. until 9 p.m. on Thursday. Heavy rain is anticipated, and multiple rounds of showers and thunderstorms could lead to flash flooding.In addition to the flash flood threat, severe storms could bring damaging wind, and t ornadoes are possible.Much of the heaviest weather will race through the area during the afternoon and evening commute.  Severe storms are bringing a flash flood threat, damaging winds and possible isolated tornadoes to the Philadelphia region on Thursday, Aug. 20, 2026. Get live updates below. Get the latest weather updates by downloading the NBC10 app and following the NBC10 First Alert Weather team. ...read more read less