Philly Winter Weather Forecast

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Some snow expected tonight for Philadelphia . #PAwx   The models are very similar with the track and timing of the storm that will move south of our area and out to sea tomorrow.

Snow will start tonight before before midnight and will essentially be over by about 8 AM for PHL.    Total amounts are expected to be 4-6 inches.   The GFS , as always, has a lower QPF than the NAM model.  (0.25 inches water GFS vs about 0.39 inches water NAM).

It will be a light, fluffy snow and any major error in predicting snowfall totals will likely be a temperature effect on the QPF :snowfall ratio.   The ratio is generally taken as 1:10, but with colder temperatures, higher ratios occur.  With scenarios like this, I think the higher QPF from NAM might be more on-target.

Areas to the south and east will have more snow, areas to the north and west less.

Again, the snow ends by 8AM, so much of the day will just be cloudy.  Sun angles are getting higher this time of year and insolation through clouds may help reduce snow cover on roads even with the “high” temps of 26 expected.

 

Winter Weather Outlook

Last Updated

An uncertain forecast. #PAwx   A shift is expected to occur in the jet stream during this coming week and the models are having a tough time predicting the path of the next storm.

Originally, low pressure was expected to move from the US Southwest to the Atlantic coast and then move up as a nor’easter Tuesday night into Wednesday.

Things have changed and now the storm is expected to move up and straight off the coast to our south Monday night into Tuesday morning, ending late morning Tuesday.   Different timing and different amounts of snow.  The GFS has a QPF of about 0.20 inches water, so 2-4 inches is the best guess.

A low confidence forecast right now.

Storm Forecasts & Other Things "up in the air".