PITTSBURGH (KDKA) – A cold front is expected to bring storms on Friday evening, putting an end to our stretch of 90-degree days.
KDKA Meteorologist Ray Petelin says it’s been very hot and overall dry, which has caused the ground to bake and most of the region to become “abnormally dry” with a moderate drought in the ridges.
The National Weather Service has issued a severe thunderstorm warning for Clarion, Washington, Beaver, Lawrence, Indiana, Butler, Armstrong, Allegheny, Fayette and Westmoreland counties until 7:15 p.m. Fayette County is also under a flash flood warning until 7:45 p.m. All other alerts have expired or been extended.
There’s also a Flood Warning for Allegheny, northern Fayette, east central Washington, Westmoreland, southern Armstrong, Butler, southwestern Clarion, southwestern Indiana, eastern Beaver and southeastern Lawrence counties in place until 9:15 p.m.
The NWS says this means between 1.5 to 2.5 inches of rain have fallen.
There have been reports of damaging winds and hail. In New Castle, a viewer sent KDKA a picture of a fallen oak tree that stood for 100 years.
Allegheny County is also reporting that a house in Crescent is on fire after being struck by lightning.
Crescent: house on fire after being struck by lightning – 180 Block McGovern Boulevard
— Allegheny County (@Allegheny_Co) July 10, 2020
Any rain we get will be welcome, but it also means the intensity of the rain could be problematic.
With the ground hardened by the dry weather and heat, runoff becomes the issue. With “precipitable water values” (the amount of water possible based on atmospheric profiles) between 1.5 and 2 inches, Ray Petelin says we could see some flash flooding in areas caught under heavy rain.
All it takes to trigger some flooding is 1.5″ in an hour. For reference, some areas saw well more than Thursday. That’s the main concern this evening. However, we could also see a thunderstorm or two become gusty.
Saturday comes with more rain, which won’t be quite as intense. This rain will start to become less prevalent during the second part of the day, Ray Petelin says, and it should stay dry through the first half of Sunday, too.
Then the next disturbance comes in with more rain Sunday afternoon and Monday. The weekend and Monday will come with more reasonable temperatures, too.
Don’t get too used to the comfortable temperatures. Ray Petelin forecasts by the middle of the new week, temperatures will take off again.
This could set us up for another heatwave, as a string of 90 degree days is possible late next week.