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Environment & Science

Forecasters: Heat could set the stage for thunderstorms to erupt across the region

Stormy weather
This graphic from the Storm Prediction Center shows the Wednesday outlook for severe weather. The Lehigh Valley is in a marginal risk (1 out of 5) area both Wednesday and Thursday.

BETHLEHEM, Pa. — A buildup of summerlike heat could set the stage for stormy weather in the Lehigh Valley and surrounding areas over the next few days, forecasters warn.

With heat and humidity on the rise, the temperature spread across the region on Wednesday will be 83 to 90 degrees, EPAWA meteorologist Bobby Martrich said in his latest video update.

That strong daytime heating will provide instability and push afternoon temperatures into the upper 80s in the Lehigh Valley.

“A very warm, summerlike day today again for the second straight day,” Martrich said, flagging a trough ahead of a cold front making its way across central Pennsylvania late in the day that could spark a few showers and thunderstorms.

The National Weather Service said storms would be mainly isolated-to-scattered in coverage, but have the potential to bring gusty winds, small hail and quick downpours to parts of the region.

The SPC weighs in

The Storm Prediction Center has outlined a marginal risk (1 out of 5) for severe weather north and west of the I-95 corridor late Wednesday and again on Thursday.

“Showers and storms could persist into the overnight period [late Wednesday] as well as the prefrontal trough lingering through early Thursday morning,” the latest NWS forecast discussion said.

Wednesday’s storms are expected to lose steam after sunset with the loss of daytime heating, and the pattern will play out again Thursday.

“I do agree with the Storm Prediction Center and their assessment on Wednesday as far as severe weather goes, because I think it’s going to be weakening as it moves further east,” Martrich said.

A couple of rounds of showers and thunderstorms will again be possible Thursday into Thursday evening, the weather service said.

“Some storms could become strong to severe, with hail or damaging winds possible. While the main threat for severe storms will be during the day and into the evening hours, there will remain the potential for showers and thunderstorms into the overnight hours as the cold front slowly continues to move across the area,” the forecast discussion noted.

The difference Thursday will be the potential for periods of heavy rainfall with any showers and thunderstorms that move through.

“We’re moving into a very soupy environment, basically is the best way you can put it,” Martrich said.