The warm temperatures we experienced today will have a brief reprieve this weekend as a low-pressure system to our south impacts our region. A disturbance forming in the Midwest will amplify off of the mid-Atlantic coast on Saturday before moving northeast. Plenty of cold air aloft from a cold front combined with a coastal storm could bring widespread snowfall accumulation from Philadelphia to Boston.
While temperatures aloft will be cold enough to support snow, they will remain close to the freezing mark. As a result, the snow will be wet and heavy, sticking to both tree branches and power lines. Heavy precipitation will begin on Saturday night and end early Sunday morning. This is a quick mover, so a majority of the precipitation will fall within a 12-hour timeframe.
A major factor associated with this storm is the track. The further south the track, the higher chance that precipitation will fall as snow in the Delaware Valley. However, the models have been inconsistent. Shorter range models are showing colder solutions and the longer-range models are showing warmer ones. The map below is from short-range North American Model (the NAM):
If the NAM is correct, 4-6 inches of wet snow could accumulate along the I-95 corridor. As evidenced by the map, the rain/snow line is only 50-100 miles south of Philadelphia. Any slight shift northward of the track could have a significant impact on snow totals, especially south and east of the city.
The GFS model’s solution shows the possibility of mixing in Philadelphia and areas south:
With this solution, 1-2 inches of snow will fall with higher totals north and west of I-95.
Regardless of the precipitation type, expect a nasty Saturday night and Sunday morning, with frigid temperatures and heavy rain/snow (depending on the track of the storm).
In the longer term, a ridge in the jet stream will set up behind this system, bringing temperatures 25-30 degrees above average! A follow-up post reviewing this warmth and long-range forecast will be published this weekend.