Category Archives: Philadelphia Area Weather Forecasts

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.

Philadelphia Area Weather Forecasts

WEEKEND WEATHER FORECAST

#Philadelphia #weather #PAwx #PhiladelphiaMarathon

Useful Link for the Model Blend (NBM) Data

Posted Saturday 11/23/24 @ 4:56 PM — The NBM is considered one of the best sources of hourly temperatures and winds and rainfall. The NWS has a link for obtaining this data in text format, albeit for local airports ( but not specific locations like Center City as I provided below.)

I’ve pre-configured the link for Philadelphia and Northeast Airports along with Wings Field in Blue Bell.

This link has been shared on this blog before, with explanations and examples to how it uses the GMT time zone (now called UTC or Coordinated Universal Time).

The hourly NBM labeled NBH is very useful once you get used to the GMT (Universal) time. (7AM here is the column labeled 12)

The extended (NBE, NBX) data is less intuitive, since as an example, next Thursday’s daytime data is shown in the column labeled 00z Friday (which occurs at 7 PM EST Thursday). You can find my NBM Text guide here.

Sunday Forecast Update

Posted Saturday 11/23/24 @ 12:06 PM — Latest NBM wind meteogram for grid point Center City Philadelphia and the marathon. Large uncertainty range (dotted lines) on wind gusts.

11-23-24 12z NBM wind meteogram for Center City (Click on image for a larger view.)

I’ve updated the regional rainfall totals map for the past 48 hours here.

Originally Posted Fri @ 6:52 PM — —The deep upper low and surface low exit our area late Friday night. Skies will clear for Saturday with high pressure building in. A weak warm front will bring a mix of clouds and sun Sunday. Clouds decrease during the mid afternoon. I’ve used the NBM data for Center City Philadelphia to cover the Marathons.

Saturday Forecast

Mostly sunny and a bit chilly and windy. We’ll still be under the influence of a cyclonic flow flow, but the GFS keeps us partly sunny.

11-22-24 18z GFS forecast for Saturday morning. The GFS keep us sunny but a cold windy flow will be noticeable. (Click on image for a larger view.)

Here’s the NBM wind/gust meteogram for Center City Saturday and Sunday—

NBM meteogram for grid point Center City Philadelphia (Click on image for a larger view.)

Sunday Forecast

A warm front will bring some clouds at times during the morning that will break mid afternoon. It will still be somewhat windy.

Here’s the NBM temperature meteogram for grid point Center City—

NBM Temperatures for Center City. (Click on image for a larger view.)