Sunday’s windy and unstable atmosphere led to hail blowing through parts of the Mon Valley and Westmoreland County, including record-setting, 2-inch hail stones.
Reports show that Perryopolis, in Fayette County, experienced hail stones that were more than two inches in diameter, which is only the third time in recorded history that Pennsylvania saw hail of that size in November, according to National Weather Service meteorologist Colton Milcarek.
“It is record-setting in terms of hail storms,” said Milcarek.
He said hail storms hit the Pittsburgh area when there is a powerful wind shear, meaning a large difference in wind speeds over short distances, and instability of air masses colliding.
On Sunday, strong winds helped to push the warm air mass that was near the surface up into the colder air mass higher up in the atmosphere. That is a perfect recipe for hail, said Milcarek, with wet rain drops rapidly freezing as they are pushed back up into the cold air mass.
He added that meteorologists were surprised by the level of instability in the atmosphere, which was several times stronger than they had anticipated.
Milcarek said hail storms hit the Mon Valley area near Perryopolis and Greensburg in Westmoreland County. He said the Perryopolis area saw the largest hailstones, which lasted about six minutes starting around 2:45 p.m. on Sunday. Greensburg saw smaller hailstones, about 1 inch in diameter, and they lasted for about 10 mins starting at 2:38 p.m.
@NWSPittsburgh nearly 2" diameter hail in Fayette County. pic.twitter.com/nziBLp8uQd
— Don (@CrashTheNet17) November 27, 2022
“It was fairly quick,” he said. “These storms were really making pace.”
The National Weather Service reported damage caused by hail across the area, including dented cars, broken windows, and even a hailstone that broke through the siding of a home.
Wind gusts were recorded up to 60 mph. Milcarek said that some hail stones were thrusted horizontally near the surface at high speeds.
Milcarek says hail storms are more typical in the spring and summer, but the Pittsburgh region could be in for a second round of hail on Wednesday.
He said Wednesday is looking to have conditions similar to what the region saw on Sunday, with high winds and atmospheric instability.
“We are looking for a semi similar setup for Wednesday,” said Milcarek. “We don’t foresee the same size of hail, but we can’t rule it out.”
