Daily Archives: Friday, December 25, 2020 9:38 pm

Philadelphia Area Weather Forecasts

WEEKEND WEATHER FORECAST

Sat 10:33 AM Forecast Review — It appears that it’s going to be sunny today and my cloudy forecast based on last night’s HRRR and RAP possibly went astray.  All a learning experience! 

Sat 11:31 AM Update — Some models still have those clouds coming in about 1-2 PM. We’ll see!

Sat 03:03 PM Update — The clouds came in at about 2 PM.

The cold front passed through this morning and the cold air has moved in Friday afternoon and evening.

The dip in the jet stream allowing cold air to move in will relax and the upper air circulation will move from a trough to a ridge on Saturday.

Several models have sunny skies for Saturday, but tonight’s HRRR and RAP models just becoming available show considerable cloudiness on Saturday, especially from Philadelphia and northward as an area of moisture and an upper air “vorticity” moves over us from the south.

HRRR upper moisture (shading) and vorticity  (Click on image for a larger view.)

I have lower than usual confidence about Saturday’s cloud cover, but I’m going with sunny early, then considerable cloudiness on Saturday, based on the HRRR and RAP models.  It will be cold and somewhat windy mid-day with gusts to 20mph.  High temp 30.4 sd 1.4º(NBM)

Sunday will be mostly sunny through thin, high level clouds from an advancing low pressure system in the Midwest. High temp 39.4º sd 1.6º (NBM model).  Winds light.

GEFS Model showing advancing clouds from system in Midwest (Click on image for a larger view.)
Weather Updates

FORECAST UPDATE

The front is moving through 9 AM, about two hours later than forecast—

HRRR model 9 AM forecast  (Click on image for a larger view.)

 

NexRad radar at 9:07 AM courtesy weathertap.com (Click on image for a larger view.)

Clouds, breaks of sun, windy and colder this afternoon. Chance of widely scattered snow flurries into this evening.