More than 50 million Americans are in the severe weather threat zone Saturday afternoon, stretching from Indiana into the Northeast.

A level two out of five risk is in place for cities including Cleveland; Pittsburgh; Philadelphia; New York City; Albany, New York; and Hartford, Connecticut. Damaging wind gusts will be the primary hazard, with isolated large hail and frequent lightning also possible with any stronger storms.

Severe thunderstorm watches have been posted across portions of Ohio, Pennsylvania, Maryland, West Virginia and Virginia — including Pittsburgh and Harrisburg, Pennsylvania; Hagerstown, Maryland; and Martinsburg, West Virginia.

Additional watches could be issued in the coming hours.

Scattered severe thunderstorms are already impacting east-central Ohio on Saturday afternoon with a few reports of downed trees so far. A line of severe storms was passing just south of Pittsburgh on Saturday afternoon.

The storms will continue to sweep east through the remainder of the afternoon and last through the evening hours. Impacts along the Interstate 95 corridor in the Northeast and New England impacts will be mostly between 7 p.m. to 10 p.m. ET.

The threat winds down after that with quieter weather on the way for the second half of the weekend.

Any stronger, slow-moving thunderstorms with torrential rain could also trigger areas of flash flooding where the heaviest rain develops.

On Sunday, severe thunderstorms are possible later in the day across parts of the northern Plains, including much of the Dakotas with damaging wind gusts and large hail the primary hazards.

Areas of heavy rain and scattered thunderstorms are also sweeping across parts of the southern Plains and Midwest this weekend. 

Flood watches have been posted from north Texas up to southwest Missouri this weekend, including Dallas; Oklahoma City, Oklahoma; and Springfield, Missouri.

Flash flooding could occur where the heaviest rain develops.

Summer heat remains in place across much of the Northeast this afternoon, however the cold front triggering the severe weather will also usher in a brief cooldown over the next couple of days. 

Highs will be closer to average for early June on Sunday and Monday.

However, this cooldown will not last long. By the middle of next week, temperatures will climb back into the upper 80s to near 90 across much of the region.