Monthly Archives: December 2018

Philadelphia Area Weather Forecasts

WEEKEND WEATHER OUTLOOK – THURSDAY EDITION

The GFS, FV3-GFS,  NBM and NAM models have all come to a consensus that this will be a rainy weekend in Philadelphia.

All models have rain for both Saturday and Sunday! (Sunday afternoon is expected to have the least amount of rain. )   The GFS from earlier this week seems to have had the best continuity with the forecast and seems to have been more accurate than the new, still unofficial, FV3-GFS.

Saturday: Cloudy with rain. High 50-55

Sunday: Cloudy with rain in the morning, intermittent showers in the afternoon.   Breezy. High near 50.

[su_note note_color=”#d9f2da”]The models have been consistent over the past week in predicting a large storm for Dec 24th, Christmas eve. It looks like rain for our area, but there’s a reasonable chance of light snow or flurries early Christmas morning as very cold air moves in behind the low pressure system. [/su_note]

Philadelphia Weather Outlook

WEEKEND WEATHER OUTLOOK

[su_box title=”Wednesday Evening Update” box_color=”#defcdc” title_color=”#000000″]Tonight’s NAM has joined the GFS in predicting rain for much of Saturday and Saturday night. The GFS continues with some showers continuing on Sunday.
The still unofficial FV3-GFS is more optimistic for Saturday evening and Sunday, as it keeps this precipitation to our south. Too early to tell.[/su_box]

The [relative] warm-up mentioned in my posting last week is on track to arrive late Friday.   Unfortunately, the milder temperatures will be accompanied by low pressure and rain.

The low pressure system arriving late Friday will be interacting with a cut-off air upper low in the southeast.  Much of the heavier rain will be Friday night and it may taper on Saturday.

There’s much uncertainty with the specifics and timing of this rain, because interactions with upper closed lows are difficult to model.

There’s some suggestion that the upper low may spawn another low pressure system for part of Sunday.  Too soon to tell.

Milder temperatures will persist into next week, with a bit of a roller coaster effect as cold air dips in several times.  It will be milder, then a day or so of cold, then milder again.

Real changes back to winter are forecast to occur around Christmas Eve with a large storm and deep cold returning.