Millions of people across the East Coast and Ohio Valley are under threat of severe thunderstorms and torrential rainfall from Friday through Sunday, following earlier storms that saturated parts of the Northeast. The atmospheric setup, with abundant moisture surging northward from the Atlantic ahead of an approaching cold front, is expected to create unsettled conditions throughout the weekend.
A cold front stretching from the Great Lakes into the central Plains will increase instability and trigger showers and thunderstorms from the Southeast into the Northeast beginning Friday afternoon. Rainfall rates could reach 2.5 inches per hour in the strongest storms, raising concerns about flash flooding in areas already experiencing saturated ground.
A Level 1 out of 4 flash flood risk is in effect for much of the Northeast, Ohio Valley, and Southeast through Saturday, impacting major cities including New York City, Washington D.C., Charlotte, and Atlanta. The National Oceanic and Atmospheric Administration's Storm Prediction Center has also issued a Level 2 out of 5 risk for severe thunderstorms from Friday afternoon across a corridor stretching from southwestern Connecticut and New York's Lower Hudson Valley through eastern Pennsylvania and parts of New Jersey into the Delmarva region. The primary threat in this corridor, which includes the I-95 corridor from New York City to Washington D.C., is expected to be damaging wind gusts.
Conversely, areas that avoid the heavy rain will contend with hot and humid conditions. Heat alerts have been issued for regions from Philadelphia to Boston, where heat index values may climb above 100 degrees, with potential extensions into Saturday. Residents across the Northeast and Mid-Atlantic can anticipate widespread rainfall totals of 0.5 to one inch, with localized amounts potentially reaching one to two inches or more if thunderstorms repeatedly track over the same locations through Sunday. Communities that experienced significant flash flooding last month may be particularly vulnerable, as areas like Bridgeport, Connecticut, have already recorded over seven inches above average rainfall this year, and Albany, New York, is more than five inches above average.