After a powerful twister touched down 50 miles west of Philadelphia, the region is under alert for possible tornadoes for a second-straight day, with potentially damaging thunderstorms also expected.

Multiple tornado warnings were issued for the Philadelphia region Wednesday afternoon and evening, with the most recent affecting parts of Bucks and Burlington Counties. The National Weather Service warned of hailstones the size of Ping-Pong balls.

Downpours set off flash-flood warnings for parts of Bucks and Montgomery Counties.

Earlier, now-expired tornado warnings issued for parts of Bucks, Montgomery, Hunterdon and Lehigh Counties.

The rest of the region remains under a tornado watch, which means conditions are favorable for the storms to possibly produce tornadoes. Thunderstorm and flood alerts were also issued for parts of the region.

The storms, packing potentially high winds, hail and drenching rains, are expected to arrive in the late afternoon and the tornado watch is in effect until 8 p.m.

On Tuesday, a tornado touched down in Morgantown, Berks County, damaging a number of buildings but causing no injuries. The weather service determined that it was an EF2, with winds up to 135 mph.

It was at least the 17th tornado reported in Pennsylvania this year, more than twice the annual average. Tuesday also was the 12th-straight day when at least eight tornadoes touched down in the United States, setting a record.

The tornado watch covers much of Pennsylvania, northern Delaware, and South Jersey down to the Shore.

Rain totals could range from "1 to 2 inches with locally higher amounts possible, " the weather service said.

A flash flood watch has been issued for most of the region, starting at 4 p.m. Wednesday and lasting until 2 a.m. Thursday.

It also will be somewhat humid with a high temperature around 87 degrees in the afternoon.

More thunderstorms are in the forecast for Thursday, when the high is expected to be about 86.

There is no precipitation in the forecast for Friday during the day and all of Saturday, but there is chance of showers Sunday.

Here’s what to do in the event of a tornado:

The National Weather Service offers this advice in the event of a tornado.
National Weather Service
The National Weather Service offers this advice in the event of a tornado.