The models continue to show low pressure development along the cold front that moves through late Wednesday afternoon. The latest GFS model cranks out over 0.65 inches of water.
The upper atmosphere cools down by the start of the precipitation, BUT the models are showing surface temperatures in the immediate PHL area not dropping below freezing. (Areas to the far north and west will have several inches of snow, if the current model forecast remains intact.)
In the the immediate PHL area, precipitation looks like it will fall as very wet snow and accumulations are likely to be limited by warm ground temperatures and warm surface temperatures. That said, it will be falling during the night time, and ice and some accumulated snow will be an issue for the morning commute on Thursday.
Right now, the low pressure system looks like it will have moved away from us shortly after daybreak on Thursday. However, the QPF values and speed of this system have continued to change and the current trend has been intensification. Stay tuned.
Tonight’s NAM model has it too warm for snow Wednesday night in the immediate PHL area. Upper atmosphere too warm and too warm at the surface. Things may change.