BETHLEHEM, Pa. — The Lehigh Valley will go beyond its average 90-degree window this year, with a heat advisory in effect and highs in the mid-90s expected Wednesday.
Allentown's (Lehigh Valley International Airport’s) average last 90-degree day was Aug. 27 during the 1991-2020 normals period, the National Weather Service said this week.
But widespread 90s are expected across the region today, with a heat advisory in effect from 11 a.m. to 8 p.m., and heat index values up to 102 expected in our area.
It’ll be our first 90-degree day since Aug. 6, when temperatures hit 91 degrees.
Overall, August has been 1.8 degrees cooler than normal. That includes a stretch from Aug. 20-23 when the average high was just 74 degrees and overnight lows dipped into the 40s.
Thunderstorm potential?
“We will have a frontal boundary moving through, but I’ll tell you what. This has been a very complicated thing, and it’s apparently complicated for the SPC too,” EPAWA meteorologist Bobby Martrich said in his latest video update.
The SPC is the Storm Prediction Center, which has the Lehigh Valley at a slight (2 out of 5) risk of severe weather on Wednesday, with damaging winds as the greatest threat in any storm.
But Martrich said we could be missing a key ingredient for storms to fire.
“The problem is, there’s not a really strong trigger mechanism,” he said.
“If one of these (isolated storms) do get going, you could have something strong and maybe see a severe thunderstorm warning, but it will be very localized and very isolated.”Bobby Martrich
The weather service highlighted two main time periods possible for storms in its latest forecast discussion: mid-to-late afternoon, and a second time frame in the evening and overnight.
But the afternoon is looking “marginal” to see anything organized, the discussion said, and Martrich said evening activity likely would be confined to areas well south of the Lehigh Valley.
“Just be weather-aware,” he said.
“If one of these [isolated storms] do get going, you could have something strong and maybe see a severe thunderstorm warning, but it will be very localized and very isolated.”
Labor Day weekend outlook
“The short term looks unsettled but not overly impactful,” the weather service said, while Martrich highlighted the possibility of some showers or storms Thursday as temperatures come way down.
Heading into Labor Day weekend, Martrich said if you have anything going on outdoors Saturday, “don’t cancel those plans.”
A slow-moving front could bring showers and storms to the area, perhaps in the late evening and overnight.
“This is the only day of the holiday weekend that shows any potential for storms,” he said.
Sunday should bring intervals of clouds and sun, and Labor Day Monday should be a mostly sunny day with temperatures in the mid 70s.
