BETHLEHEM, Pa. — Strong to severe thunderstorms are expected to bring damaging winds and several tornadoes Monday from the Ohio Valley into the mid-Atlantic, but may not live up to their potential in the Lehigh Valley.
That’s the word from EPAWA meteorologist Bobby Martrich, who said cloud cover will limit instability in the region.
Clouds can limit thunderstorm development by acting as a cap, preventing the upward movement of warm, moist air needed to fuel thunderstorms.
Additionally, clouds can reduce the amount of solar radiation reaching the surface, also limiting atmospheric instability.
Martrich’s outlook differs from the Storm Prediction Center, which has a large swath of the middle Atlantic under a slight (2 out of 5) risk of severe weather.
“I will tell you that I do not agree with this,” Martrich said in his latest video update. He said a marginal (1 out of 5) risk would have been sufficient, and only for a certain area.
“We have a difference of opinion,” he said. “This is not uncommon for us to disagree with the SPC.”
Martrich highlighted an area from right around or just north of the Lehigh Valley all the way below southern Pennsylvania and into Maryland as having the potential for isolated severe storms.
He said model soundings showed “just barely enough instability to work with,” again mentioning how cloud cover will limit instability despite “all the other parameters looking pretty decent.”
Martrich said the primary threat with any storms will be gusty winds of 30 to 40 mph, with timing around and after 7 p.m. in the Lehigh Valley.
What the SPC is saying
The Storm Prediction Center does note that “instability is expected to weaken with the northward extent ahead of the cold front” moving in.
“Still, scattered thunderstorms should develop this afternoon and spread east-northeastward toward the coast through the evening,” forecasters said in Monday’s day 1 convective outlook.
⚠️⛈️ No significant changes to the forecast for today. Thunderstorms between 4 PM to midnight will bring potential for locally damaging winds and localized flooding. A brief tornado and hail are possible as well. Remain alert for changing conditions! #PAwx #NJwx #DEwx #MDwx pic.twitter.com/zd9PRDE17a
— NWS Mount Holly (@NWS_MountHolly) March 31, 2025
According to the outlook, “some of this convection may pose a threat for damaging winds and perhaps a tornado or two, before it eventually moves offshore.”
What’s next?
Unfortunately, it will be noticeably cooler Tuesday and Wednesday in the Lehigh Valley.
The National Weather Service is projecting highs in the low 50s under mostly sunny to partly sunny skies.
Temperatures are expected to rebound Thursday and Friday, but with more rain on the way before it gets cooler again by the weekend.
