Severe thunderstorms tore through the region again on Friday evening, punctuating some of the wildest few days in the region’s weather history with several reports of downed trees and rainfall of up to six inches reported in Chester County.
“It’s just amazing to have this many big weather events in one week’s time,” said Dave Houk, a meteorologist with AccuWeather Inc.
The storms again targeted Chester County, with West Chester reporting six inches of rain, and then pursued a path of mayhem eastward through parts of Delaware County, northern Delaware, and South Jersey, with numerous reports of downed trees and flooded roads.
Evacuation orders were reported in Aston Township, Delaware County, where 3.51 inches of rain — that’s a normal month’s worth — fell in just 50 minutes.
Chester Creek had risen to 13 feet as of 8 p.m., five feet over flood stage.
Elsewhere, an 89 mph gust was measured in Cumberland County, N.J.; flooding closed the New Jersey Turnpike in both directions between the Delaware Memorial Bridge and Route 322; and I-95 southbound in New Castle County, Del., was closed due to flooding.
Trees came down in Chester County, and in northern Delaware ripped down some wires near the Edgemoor Gardens complex, possibly trapping some people inside.
Tropical Storm Isaias left up to eight-plus inches in the region, and spawned a number of tornadoes, including one that struck Northeast Philadelphia. Some of the areas hardest hit by Isaias got it yet again Friday.
The region has been caught in persistent moisture plumes, lying between a system to the west and high pressure over the Atlantic Ocean that is importing humid air from the subtropics as part of its clockwise circulation, said Houk.
“It’s just a big channel of deep moisture form the Carolinas northward,” he said. Unfortunately, in summer, the upper-air steering currents can get very stuck in their ways.
“It seems like each day, we’ve seen disturbances coming from the southwest,” he said. “They’ve grown into pretty big complexes of storms.”
The rain Friday likely got at least an additional measure of juice from Isaias, which not only left the ground saturated, but left the August foliage quite wet — and another source of moisture, he said.