Category Archives: Philadelphia Area Weather Forecasts

Philadelphia Area Weather Forecasts

WEEKEND WEATHER FORECAST

#Philadelphia #weather #PAwx

Forecast Update

Posted Saturday 12/07/24 @ 9:38 PM — The weather for the Eagles game on Sunday will be sunny (some occasional thin high cirrus clouds at times.) Unfortunately, the departing clipper system will result in a pressure gradient that results in somewhat windy conditions, with gusts as high as 28 mph, somewhat diminishing later in the afternoon.

High temperatures will be 54º-55º near the stadium and 52ª-53º Blue Bell.

A warm front is still expected to bring light rain and drizzle on Monday, dry but cloudy for much of Tuesday, then heavy rain (1.5+ inches) Tuesday night into Wednesday before a strong cold front moves through with high winds Wednesday afternoon. Maybe some snow flurries Wednesday night.

Combined 18z NAEFS forecast with Bias-Corrected GEFS model 6 hour precip for Wednesday 7 AM. (Click on image for a larger view.)
Runs of the experimental RRFS model that I’ve been having fun with have been put on hold while the model is being evaluated for possible release next year. This was a planned pause. My page on the RRFS has some of the history.

Originally Posted Fri @ 6:36 PM — —The upper air trough that brought us the cold weather will move off to the east and allow temperatures to moderate Saturday night into Sunday.

An clipper type low pressure system moving well north of us will bring some clouds later Saturday as a southwesterly flow develops and moisture moves aloft as a pseudo warm front. That moves away on Sunday allowing skies to clear. The departing clipper will cause it to be windy on Sunday.

A southwesterly flow of milder air will be with us for Monday through Wednesday.

With the milder air, moisture and rain will move in on Monday. Some interesting weather developing Monday through Thursday ahead of another deep dip in the jet stream. Low pressure systems are expected to move up from the southwest ahead of front giving us clouds and rain.

GFS forecast for next Wednesday at 7 AM. Low pressure systems develop and move up over us through Wednesday (Click on image for a larger view.)

Saturday Forecast

Sunny and still cold. Clouds move in about 3 PM due to a pseudo warm front brought north by a clipper system.

NBM high temperatures: Blue Bell, PA 38º Philadelphia, PA 40º
Low uncertainty (based on standard deviation): ± 1º

Sunday Forecast

Sunny, milder and somewhat windy. Clouds move in late.

NBM high temperatures: Blue Bell, PA 51º Philadelphia, PA 53º
Average uncertainty (based on standard deviation): ± 1.3º

Philadelphia Area Weather Forecasts

WEEKEND WEATHER FORECAST

#Philadelphia #weather #PAwx

Week Outlook Early Edition. Snow??

Posted Sunday 12/01/24 @ 9:21 AM — First, today’s morning clouds were predicted and but the latest models have these clouds hanging tight for most of our area through 4-5PM, instead of dissipating earlier. (Far northern areas may see some sun by afternoon.)

As for this week, all the radio and TV forecasters are using the word “SNOW” for late Wednesday into Thursday. My personal feeling is that after months of sunny skies and no rain, they’re starved for attention. I don’t see much in the way of any meaningful snow deserving this sort of hype.

Since last Friday, the models have been hinting at some snow late Wednesday into late Wednesday night. The truth is, the reinforcing cold front responsible for this “snow” is moisture starved and over the past several days, the models have shown very little to suggest that we’ll get anything more than snow showers. Right now, I see only snow showers that may give a coating in most areas. I don’t see the need for snow shovels. Perhaps an ice scrapper for your car Thursday morning to remove frozen melted snow from your car windows.

The latest GFS and the caption below explains the situation—

12-01-24 06z GFS. for 7 AM Thursday. White line is surface 32º Light blue line is surface 36.5º, the approximate minimum temperature for snow. Basically it’s too warm in the lower levels of the atmspherre for snow to accumulate. The upper level critical temperatures for snow (lavender) , 500-1000mb thickness (red) and ( magenta) support snow formation, snow will melt on the way down. The blue tint among the green precipitation field is where the GFS predicts snow falling, mostly north of the 36.5º line. (Click on image for a larger view.)

I’ve been keeping an eye on this situation, but, if your’e hoping for real snow, you’re likely going to be disappointed.

Originally Posted Fri 6:34 PM —We had the instability showers/snow showers today as forecast yesterday by the RRFS and GFS. Those will be ending with sunset, as cold air streams in from the northwest.

A broad dip in the jet flow will cause cold weather to be with us through the weekend and into much of the next week.

Current satellite water vapor image with superimposed RAP model 500-1000 mb thickness lines (yellow), Mean Sea Level Pressure isobars (black contours) potential vorticity (fine violet contours) with superimposed Composite RADAR. (Click on image for a larger view.)

For Saturday, cold with instability cloudiness again about noon into early afternoon. No showers expected. Sunday continues sunny and cold.

Saturday Forecast

Sunny in the morning, instability cloudiness towards noon into the early afternoon, then skies clear. Windy during the mid-day hours. Temperatures in meteogram below. Wind chills (‘apparent temperatures’ in the meteogram) below 30º

Sunday Forecast

Some warm air aloft from a southwesterly wind will cause some cloudiness during the morning hours, then partly sunny. Still somewhat windy mid-day into early afternoon.

A weak cold front moves through Sunday evening dropping temperatures.

NBM forecast temperatures for Blue Bell, PA (Click on image for a larger view.)
Looking Ahead

A cold front with a possible interaction with some southern jet stream energy will bring some very light showers or showers with some snow flakes later Wednesday. There’s uncertainty with is system.