Heavy showers and strong-to-severe thunderstorms pounded much of the region late yesterday from DC-to-Philly-to-NYC, but today’s action could be even stronger with the potential for more extensive and greater damage. The explosive combination of a vigorous upper level low, strong upper level jet streak, strong surface cold front, and excessively humid air will lead to widespread showers and thunderstorms from this afternoon through tonight and even into early tomorrow morning in some areas. There is currently no "severe thunderstorm watch" for the region, but that will very likely be issued by the National Weather Service later today. The eastward progress of the strong surface cold front will slow later today/early tonight as upper level winds along the east coast become parallel to the “north-to-south” oriention of the frontal system. This will inhibit eastward movement by the front for several hours leading to the possibility of a serious dumping of rain across portions of eastern PA, southeastern NY, the Delmarva Peninsula and all of New Jersey. As a result, localized flooding is a serious concern as 2-4 inches of rain can fall in some areas in a relatively short period of time on top of already well-saturated grounds.
In addition to the flooding concerns, power outages are also a threat in parts of the region later today/early tonight caused by strong thunderstorm activity. The greatest threat for damaging thunderstorms will be between 2pm and 9pm in the I-95 corridor from DC-to-Philly-to-NYC, but heavy showers and strong thunderstorms can occur before and after that “severe weather” timetable and could even last into early Wednesday morning in some areas. The good news is that a refreshing air mass will push into the region later Wednesday with a substantial drop in overall humidity levels, but we’ll have to pay a price before we experience the invigorating change. Stay tuned.