Over 25 million under alert for severe weather, possible flash flooding in Northeast

Strong to severe thunderstorms are sweeping across parts of the Northeast on Saturday afternoon, putting more than 25 million people on alert.

A severe thunderstorm watch has been issued for parts of the Northeast, from Maryland to Maine, until 8 p.m. ET.

This includes much of the Interstate 95 corridor, including Baltimore, Philadelphia, New York City and Boston. 

The primary hazard from any severe thunderstorms that develop is strong, potentially damaging wind gusts. Isolated large hail and a brief tornado or two cannot be ruled out, especially for locations in northern New England included in the watch.

Any slow-moving thunderstorms with torrential rain could also trigger localized flash flooding, especially in urban, poor-drainage areas, and bring frequent lightning. 

Damaging winds, large hail and lightning will be possible early Saturday evening into the overnight across this area, with a slim risk of a few brief tornadoes.

Flash flooding will also be a concern for some of these areas, with the highest risk (Level 2 of 4) stretching from Philadelphia to Bridgeport, Connecticut.

Multiple rounds of heavy rain from overlapping and training storms will be capable of producing localized to scattered areas of flash flooding, especially with the heaviest downpours or in areas known to flood.

The storms are expected to continue into the overnight hours.

Cooler air will be sweeping in behind this front, as another round of refreshing, fall-like air moves from the Midwest into the Northeast for the second half of the weekend.

 In true fall-fashion, the cool air will not stick around long, gradually warming is expected throughout next week, from west to east.