East Coast rain threat prompts 51 NYC shelters as flash-flood risk grows

A line of thunderstorms sweeping from Washington, D.C. to New Haven, CT prompted flood alerts for about 39 million people. New York City opened 51 weather shelters for residents at risk, especially those in basement or below‑grade units. The National Weather Service issued flood watches for portions of Maryland, Pennsylvania, Delaware and New Jersey, with NYC’s watch running 4 a.m.–noon Sunday. Forecasters warned 5–7 inches of rain could fall in Nassau and Suffolk counties and southern Connecticut, with eastern Brooklyn and Queens at higher flash‑flood risk if the rain’s setup shifts. The threat stems from a clash of cool air aloft with moist, warm air, increasing the chances of excessive rainfall and severe thunderstorms.