Philly Winter Weather Update

The latest NAM and GFS model data has become available.  Here are the trends:  Both models have the precipitation arriving earlier than previously predicted on Sunday.

The snow will start in the early afternoon.

As always, the NAM has a higher QPF than the GFS,  with almost 0.47 inches water falling.  The NAM is also colder than previous model runs.  The NAM has done well with temperatures, but has been over-stating QPF.

So there is the possibility of accumulating wet snow Sunday afternoon into Sunday evening before a changeover to sleet and freezing rain during the evening.  1-3 inches snow possible. It’s   difficult to determine  accumulations- higher sun angle this time of year, so roadway surfaces tend to not develop as much accumulation during the day.