Connellsville weather event, flooding analyzed
Roberto M. Esquivel | Herald-Standard
In this file image, emergency personnel divert traffic away from floodwaters across Route 119 near Bellview Road in Connellsville on Aug. 28.
Jack Hughes
It’s been a little over a month since historic rainfall and flooding devastated the Connellsville area and the surrounding communities, causing nearly $7.7 million in personal damages by impacting more than 150 homes, according to the Fayette County Emergency Management Agency.
According to a local weather observer, the storm on Aug. 28 was just one of four possible ways Mother Nature brings an onslaught of rain and potential flooding to our region.
“In the summertime, it’s not unusual for a storm to build up right over top of an area — usually a warm, moist air mass is in place. From there, showers develop and instead of moving, the storm system just sits there,” said Jack Hughes of Chalk Hill.
Also known as the mountain weather observer, Hughes has spent decades recording and reviewing weather data.
“It’ll drop inches of rain, and you’ve got a disaster in the making,” he said.
“Water has to go down hill. In a very short period of time, you’ve got this mass of rainfall that has nowhere to go,” he added.
In a matter of minutes, storm sewers, waterways and valleys become inundated with water, causing banks to overflow. Hughes said the Aug. 28 weather event had a combination of hilly terrain and excessive rainfall.
“After raining profusely for a couple of hours, it dissipated, right over the same area that it formed,” Hughes said. “Those are the dangerous ones with a lot of water in a short period of time.”
“Fortunately, those don’t affect widespread areas. They’re localized in nature,” he added.
That night, weather records indicate that the Connellsville area got nearly five inches of rain, while areas less than 50 miles away in various directions received little to no precipitation.
Chad Kauffman, a professor with California University of Pa.’s meteorology program, said the weather that night was part of a larger group of storms, mostly triggered by a front boundary to the north and west of Pittsburgh.
Weather data from the Weather and Storm Prediction centers indicated that the region “had been highlighted very close to the ‘marginal risk’ region, meaning forecasters had some concern about the chance for severe-type thunderstorms,” he said.
“The weak flow aloft may have been a contributing factor to the slow movement of these thunderstorms in the region,” Kauffman said, referring to upper-level winds. “The slow flow aloft, however, is not unusual for late summer.”
In addition to localized, stalling weather systems, Hughes said torrential rainfall and inevitable flooding can also be brought to the region by winter snow melts with warm rains. Another possibility is through a derecho, or a cluster of showers, wind and thunderstorms bringing widespread rainfall totals — much larger than the Connellsville event, Hughes said.
“They don’t happen very frequently, but they’re extreme rainmakers,” Hughes said.
The more common source of excessive rainfall to our region, however, are tropical storms. Though they don’t hit this far inland, Hughes said, their remnants can be felt several states in from the coast.
Hughes recalled June 1972 when Uniontown got 4.34 inches of rain from Hurricane Agnes, while central parts of the state received close to a foot of rain. Another similar weather event from Hurricane Carol in October 1954 brought 4.60 inches of rain to Uniontown.
Kauffman, who has lived in the region for about 15 years, said he couldn’t recall a localized devastation from heavy rainfall like the one in Connellsville.
“Everyone who was here for Ivan’s remnants in 2004 likely remembers that event, but Ivan’s rainfall impacts were much more widespread throughout the region and tropical in origin.”