Temperatures throughout the region stayed well in the 50s on Tuesday afternoon, and that could have a significant — and benign — impact on the Wednesday morning commute.
Snow, perhaps an inch in Philadelphia and possibly a touch more to the usually cooler places, is almost a certainty during the overnight hours and after daybreak Wednesday, as temperatures take a serious tumble into the 30s.
The likeliest time for the heaviest snow in the immediate Philadelphia would be between 4 and 7 a.m., the National Weather Service says.
Ordinarily that timing would be about as bad as it could get for motorists, and it is still possible that some roads in the region could get dicey for awhile given that this would happen before the sun became a factor.
However this might well turn out to be just a decorative snowfall, layering the tree branches and mailboxes.
Thanks to this week’s temperature run-up, the all-important “skin” temperatures — the readings where rubber meets road, as opposed to the “ambient” or air temperature — should remain well above freezing.
Thus the snow will have a hard time sticking to paved surfaces, said Nicholas Carr, a meteorologist at the National Weather Service office in Mount Holly.
“That’s good for us,” said PennDot spokesperson Brad Rudolph. Crews would not be pre-treating roads with brine because of the rain, he added.
The cold front due to plow through the region Tuesday night will send a chill through the atmosphere, and eventually the rain is forecast to change to snow during the early-morning hours.
In this instance, the snow would be what meteorologists call “anafrontal,” a fancy term meaning the precipitation would come in the wake of the front. Usually it’s the other way around.
The most likely time for snow would be from about 2 until 8 a.m., Carr said.
After the snow stops, the sun will re-emerge, although the realities of December will be evident as temperatures hold in the 30s Wednesday and won’t get much past freezing on Thursday.