For the first time since — let’s see — Wednesday, the government’s Storm Prediction Center issued a severe-thunderstorm watch for the Philadelphia region Thursday, in effect until 9 p.m.

Some strong storms with heavy downpours popped up in the region late in the afternoon, and the National Weather Service posted several reports of downed trees in Burlington County, including one that fell upon a house.

The weather service issued a flood advisory for portions of Philly, and Chester, Delaware, and Montgomery Counties where it said 1 to 1.5 inches of rain had fallen.

A flood watch remained in effect for Philadelphia, the nearby Pennsylvania suburbs, Camden, and Gloucester Counties, and part of Burlington County until 10 p.m.

A cold front approaching the region was forecast to incite the warm unstable air that has settled over the area.

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“The sun broke through, and it got pretty soupy out there,” said Jonathan O’Brien, a weather service meteorologist.

The storm center said that “numerous storms” could develop, leading to a “more clustered” storm pattern. Flash-flooding is possible, depending on how the storm cells align, the weather service said.

Also, the probability of tornadoes is quite low, the agency said.

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“it’s kind of a typical summertime thunderstorm setup,” said O’Brien.

Why do these watches keep popping?

It is that time to year. Among the months, June ranks No. 2 in the average number of days with thunderstorms in Philly, at 5.3, or about 20% of the annual total. No. 1 would be July at 5.7, with August third at 5.1.

Meteorologically, that’s called summer.