Once again the government’s Storm Prediction Center has parts of the region, just to the north and west of Philadelphia, in a “slight risk” for severe storms Friday.
But this time a repeat of the random flooding downpours that have ambushed different areas around here is highly unlikely.
For a change, with a front approaching the atmosphere should show some signs of breaking out of the typical summer torpor that leads to upper-air doldrums.
The upper atmosphere tends to rock between the waves in summer as solar energy is spread more evenly, and the temperature contrasts that drive winds slacken.
That languid behavior, unfortunately, can contribute to flooding rains, and late Thursday was yet another case study.
Five inches of rain was measured in parts of Burlington County, with 1.42 inches falling in 25 minutes near Burlington City. Not surprisingly, that set off serious flooding.
The rains were focused on a roughly 20-mile long corridor from Tullytown, Bucks County, near the Delaware River, where 1.15 inches of rain came in a 15-minute spurt, into Burlington County.
“A cluster of storms set up over the same spot,” said Mitchell Gaines, a meteorologist at the National Weather Service Office in Mount Holly. “Then a second cluster of storms got stuck in the same spot.”
As often happens when rains are so focused, nearby areas were rain-deprived. Philadelphia International Airport, for example, got almost nothing.
Trenton, only 17 miles from Burlington, received a grand total of 0.18 inches.
Rains Friday night should be spread more generously, and probably less traumatically.