Winter Weather Update

Latest NAM and GFS models show light snow starting mid to late morning with a changeover to sleet and freezing rain during the late afternoon. The NAM has much heavier rain/freezing rain in the evening. Not much in the way of accumulations, but significant icing conditions possible, especially north and west of the city.

The precipitation ends after midnight.  Temperatures may remain just around freezing, making things slippery for the early Monday morning commute.

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.

Philly Weekend Weather Forecast

Cold high pressure will bring fair skies and cold temperatures to our area on Saturday.  Highs will be in the low 30s.

The high pressure system drifts east and a return flow of moisture will bring clouds on Sunday.  Most of Sunday will be cloudy with high near 32.

Towards Sunday evening, light snow will develop but will mix with sleet and then freezing rain during the evening.

Since ground temperatures have been below freezing and the precipitation is occurring at night, a period of sleet and freezing rain may make driving difficult Sunday evening and night.

The sleet changes over to rain some time after midnight and ends about daybreak on Monday.

Weather… and Other Things 'Up in the Air'