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Flood watch for Philadelphia region until 2 a.m. Saturday as more rain due to pour atop Isaias’ leftovers

This is just about what we don’t need.

Kelly Drive at Midvale Avenue is flooded after Schuylkill River overflows.
Kelly Drive at Midvale Avenue is flooded after Schuylkill River overflows.Read moreALEJANDRO A. ALVAREZ / Staff Photographer

The region needs this about as much as an overflowing sink needs a running faucet.

The National Weather Service has extended and expanded a flash-flood watch for the entire region into early Saturday as the aftereffects of Tropical Storm Isaias persist.

Showers and thunderstorms doused parts of the region Friday morning, with a flood advisory in effect in upper Bucks County. The weather service says more downpours are possible late in the day into the evening.

Given that the region is still trying to dry out from Isaias’ soaking rains — 8-plus inches in some places — and another round of showers Thursday morning, “it will not take much rain to result in flash flooding,” the agency said.

» READ MORE: Isaias’ aftermath brings a massive cleanup at flooded homes, prolonged outages, and a closed Vine Street Expressway

A weak frontal feature that isn’t going anyplace has settled overhead, and the air still is full of moisture, the weather service says. And thanks to Isaias rains, all that wet foliage is supplying some additional juice.

» READ MORE: Isaias could leave some customers in Pa., N.J. without power through the weekend

The flood watch, which also covers all of Delaware and Central and Southern New Jersey, officially is in effect until 1 p.m., but chances are good it will be extended, said Dean Iovino, a lead forecaster at the weather service office in Mount Holly.

And shower chances continue Friday night into Saturday before things dry out and modest heat returns. Highs on Sunday could approach 90 and reach the low 90s on Monday.

At least Isaias is long gone, having ended its career in Quebec, and for now forecasters are expecting a lull in what has been a record-setting Atlantic tropical storm season. Never in the period of reliable data have nine named storms, those with winds of at least 39 mph, formed this early. On average a ninth doesn’t occur until October.

However, based on the updated hurricane outlooks, Isaias and its predecessor, Fay, may turn out to be mere preludes.

Typically, the June 1-Nov. 30 season doesn’t get cooking until mid- or late August, and doesn’t reach its climatological peak until Sept. 10. On Thursday the government predicted the 2020 season would be “extremely active” the rest of the way, with as many as 25 named storms; the average is 11.

That is in line with other outlooks as conditions appear favorable for hurricanes through the Atlantic Basin, which includes the Gulf of Mexico and the Caribbean.

While tropical storms and their remnants can be quite disruptive, Isaias did bring the region one residual benefit.

As recently as Tuesday morning, Philadelphia was running a 1.15-inch precipitation deficit for the year, according to the weather service.

Isaias’ 4.16 inches officially in the city on Tuesday, which broke the daily record set on Aug. 4, 1915, brought the precipitation total since Jan. 1 to 27.9 inches, almost three above normal.

And by day’s end Tuesday, according to the Middle Atlantic River Forecast Center, every county in the region had received a near- or well-above-normal total for 2020.

Those numbers might go up again on Friday.