Philly Weekend Weather Forecast

Once again, today’s (Friday) model forecast was far off target.  We were supposed to have clouds and showers throughout the day.   Not the case!

I’m not so sure we can count on the model’s weekend forecast to be on target.  It appears that the NAM did better than the GFS so we’ll go with it.

The NAM shows heavy rain Saturday morning, ending early afternoon. (The GFS also shows some rain, but significantly less.) Clouds break late Saturday afternoon as winds pickup.  High about 60.

Saturday night becoming very windy and cold as low pressure tracks through Pennsylvania.  Chance of a wet snow flurry!

Sunday, mostly sunny, windy and chilly.  High 45.

I may need to update this forecast.  A bit below usual confidence.

Update Saturday 6AM:  The NAM has showers into early afternoon today (QPF 0.26 inches water), then some brightening skies possible mid afternoon before some more clouds move in towards evening.  Still a chance of a quick sprinkle in the late afternoon.  A wet snow shower increasingly likely around midnight as winds pick up.

For Sunday, mostly sunny, very windy and chilly.  Winds subside in the afternoon.  High 44.

Philly Weekend Weather Forecast

Perhaps no one noticed, but the models did very poorly with today’s (Friday ‘s) forecast.  There was supposed to have been heavy rain followed by sun in the afternoon. Neither occurred. Let’s see if the weekend forecast is more accurate.

A frontal boundary draped near the Great Lakes won’t move until Monday.  (At least that’s what the models show.) High pressure builds in Saturday.  Mostly sunny skies with high temperatures near 55.

Late Saturday,  high pressure retreats to the northeast and an easterly flow of moisture develops causing low cloudiness.  Mostly cloudy skies expected for Sunday with high temp again near 55.

Saturday Update:  I want to mention that the long range models have been consistently showing an outbreak of deep cold air for next weekend, the beginning of April.  Winter has at least one more guest appearance.

Sunday Weather Update

The latest NAM model data becoming available at this time.  (When in Eastern Standard Time, some data is available as early as 9:10, but with Daylight Savings Time, all models are available an hour later local time.).

The latest NAM data shows snow for our area, but again with a fast cut off north and west of PHL.  Latest QPF values are in line with last night’s GFS- about 0.21 inches water, mostly falling during the evening hours.   1-2 inches in PHL possible, mostly on grassy surfaces, more in areas of NJ.  Snow starts late this afternoon here in PHL and goes through a little after midnight. (Much earlier in Delaware where they may have a more significant accumulation. )

Here’s the NAM forecast map for the 3 hour period prior to 10 PM tonight

NAM Forecast for the three hour period prior to 10PM tonight
NAM Forecast for the three hour period prior to 10PM tonight

Notice how the bullseye for the snow is just east of PHL.  Small variations can again blow this forecast.

1PM Update-  This morning’s GFS has the precipitation further east and barely reaches PHL. So this could be another zero.

8PM Update- There is some snow falling, but surface temperatures in the region  just seem too warm for any accumulation.  .

Weather… and Other Things 'Up in the Air'