A frontal system is combining with the well-established excessively humid air mass, surface low pressure, and potent upper level support to once again raise the prospects for severe weather later today in the Mid-Atlantic region from DC-to-Philly-to-NYC and all the way eastward to the coastline. Heavy showers and embedded strong thunderstorms are currently increasing in coverage and intensity across central and western Pennsylvania and they are moving eastward into increasingly unstable air. The result will be more heavy rainfall in this region between 3 and 9PM and the likelihood of some severe thunderstorm activity to include hail, torrential rain, and damaging wind gusts. Flash flooding will once again become a serious concern later today and early tonight as grounds are super-saturated – any roadways with water should simply be avoided. The threat for showers and thunderstorms will continue well into next week with additional heavy rainfall likely, but I will say that the areal coverage of the rain is liable to be substantially diminished tomorrow with much in the way of rain-free time.