Still away on vacation 🌴, but I thought I’d chime in on the weather for Tuesday.
An upper air disturbance will move across the area on Tuesday. The latest NAM model has moved up the QPF to about 0.20 inches water. Upper air temperature profiles marginally support the precipitation falling as snow, BUT near surface air temperatures will likely be above freezing for much of the time. Additionally, ground temperatures have been above freezing for awhile.
As a result, a very wet snow is expected with very little accumulation — likely just a coating, more on grassy surfaces.
Tonight’s NAM data just rolled in. QPF values are again very low in the immediate PHL area, about 0.09 inches water. With some of that falling before surface air temperatures fall to 32, it would appear that the best guess is a coating to 1 inch in PHL and the immediate suburbs.
Areas farther north and west may have 2, possibly 3 inches.
The biggest issue, regardless of accumulation, will be that any wet accumulations will become icy in the morning, with temperatures dropping below freezing for a time. Stay safe!
The latest NAM model data has come in. Here are the trends—
The snow starts later in PHL, closer to midnight Tuesday. QPF values are increasing, now 0.33 inches water, somewhat more north and west of the city. The snow continues into Wednesday morning. This translates into 3-4 inches.
So weak frontal passage seems to be evolving into more than a nuisance snowfall. Expect further changes.
11 pm update: The GFS has less QPF in the immediate PHL area, more north and west. For now, we’ll average the two models. 2-4 inches of snow is a best guess for now.
