Philadelphia’s weather is about to get nicer, and that’s connected to Florence

While residents of the Carolinas are enduring a nightmare wrought by Hurricane Florence, the Philadelphia region is about to experience an entirely different change in the weather.

"Overall it should be a pretty decent weekend," said Lee Robertson, a National Weather Service meteorologist in Mount Holly. For now no rain is in the forecasts for Saturday and Sunday, with the September sun warming temperatures to around 80.

While the outcomes in the Carolinas and the Philadelphia region couldn't be more disparate, they are very much related.

Attention — at times obsessive — naturally has been focused on the path of Florence, which on Friday morning made landfall near Wrightsville Beach, N.C., as a Category 1 hurricane, with peak winds of 90 mph.

But a big player has been an area of high pressure over southeastern Canada that has suppressed Florence and protected the Northeast from the hurricane's wrath.

Under descending currents of high pressure, the air is literally heavier and tends to discourage clouds and rains, which need rising air to develop.

But that protection will break down. Florence's remnants are likely to affect the Philadelphia region Monday into Tuesday, according to the weather service, but the region will see nothing like the projected 20 to 40 inches of rain in North Carolina.

A cold front is forecast to interact with Florence's remnants to accelerate it northeastward later in the weekend and across Pennsylvania, close enough to affect Philadelphia.

The weather service now sees a high likelihood of showers and thunderstorms Monday night and Tuesday, with rain possibly starting during the day Monday. The atmosphere around here would be primed and vapor-rich.

But for now, it's entirely possible that the region will have only its third rain-free weekend since the beginning of July.

The timing of any impacts would hinge on when Florence catches up with inland steering mechanisms and moves northward, and the local impacts will hinge on how close the center comes to Philadelphia.

Close to 8 inches of rain has fallen citywide in Philadelphia in the last 30 days, according to the Middle Atlantic River Forecast Center, with more in the counties to the west.

As Florence gets closer, the region might well get caught in a wind sandwich, as the lower pressure of Florence interacts with the higher pressure to the north. Winds move from highs to lows like air leaking from a tire.

In the short term, Philadelphians should savor their good weekend fortune and hope for the best for Carolinians.

"We're going to be in a sweet spot — for a while," said Dave Dombek, a meteorologist with AccuWeather Inc.