The stage is being set in the atmosphere for some potential fireworks this evening across the I-95 corridor from Philly to New York City. An increasingly cool air mass is now sliding down through New England into southern New York (back door cold front) while simultaneously, record or near record-breaking warmth has settled in across southern Pennsylvania, northern Maryland, Virginia and the DC metro region. In fact, temperatures today have climbed to near 90 degrees in the DC metro region and into the middle 80’s around Philly, but have dropped into the low 50’s up the coastline in Boston, MA. Meanwhile, an impressive band of showers and strong thunderstorms has fired up this afternoon across eastern Ohio and western Pennsylvania, and it is charging eastward right into this clash of air masses along the I-95 strip. Additional showers and thunderstorms are lining up farther to the west across the Ohio Valley and they too will likely affect the I-95 corridor in the overnight hours. The end result will be numerous showers and strong thunderstorms between about 6pm and midnight in the region from Philly to NYC and some of the rain will fall heavily at times. Also, hail is a possibility with some of the strong storms as well as frequent lightning and wind gusts to 50 mph or so.
The cool air mass now in place across New England will continue to press to the southwest overnight, and it’ll be noticeably cooler tomorrow in NYC and Philly as compared to today, but the DC metro region will likely have a minimal impact by this back door cold front and should still reach the 80 degree mark for highs tomorrow afternoon. More rain and thunderstorms threaten the entire Mid-Atlantic region later tomorrow night and Friday from a more conventional west-to-east moving cold front and some of that rain is likely to be heavy.