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Philadelphia Weather Outlook

THIS WEEK’S WEATHER

#Philadelphia #weather #PAwx

Posted Wednesday 02/26/25 @ 9:02 PM — After a mostly sunny day on Wednesday, we’ll see clouds move in for Thursday. Very light scattered showers will be with us by morning and continue into the afternoon.

As has been the case lately, we’ll see only 0.10″ of rain or less. The Philadelphia area has been in a “doughnut hole” of rain with most systems for the past 9 months or so. As mentioned in my forecast review, I don’t currently see a change in that pattern in the extended forecast range of 2 weeks.

For tomorrow, the new AI model from the ECMWF captures the pattern of the heavy rain bypassing our area—

18z ECMWF-AIFS SINGLE model rain accumulation forecast through Friday morning. (Click on image for a larger view.)

Tue 9:31 PM —Forecast Review — We had much more sunshine than forecast today. The lack of showers was not a surprise, as the forecast for scattered amounts in the 0.01 to 0.02 range can often be model “noise”.

That said, I see a continuing lack of significant rainfall in our area. We went into the winter with a rainfall deficit and we have had only a few decent rainfalls over recent months. I don’t see much in the way of heavy rainfall in the extended model forecasts. A case in point— a week ago, the models suggested a decent rainfall for this Thursday. Current model forecasts are showing a minimal amount of rain on Thursday.

That trend towards lower rainfall amounts in the model forecasts has continued. The basic pattern has been for rain to move off to our northwest or out in the Atlantic. If this pattern continues, we’ll have some significant rainfall deficits by late Spring.

Here’s the latest total accumulated rainfall forecast for Thursday, based on the new AI model, the “ECMWF-AIFS-Single”—

18z ECMWF-AIFS Single total rainfall by 1 AM Friday morning. (Click on image for a larger view.)

Tuesday Forecast

Posted Monday 02/24/25 @ 6:17 PM — The weak front that moves through on Tuesday is expected to bring plenty of clouds and mild temperatures despite the lack of sunshine. Some sprinkles are possible anywhere from 3 PM to 7 PM, but any precip will be extremely light, on the order of 0.01 to 0.02 inches of water.

It should be noted that the ECMWF and the new ECMWF “Single AI” model show no precip at all in Philadelphia and very light precip to the far northwest, near Allentown and Reading. Depending upon the models, the clouds may dissipate late afternoon or hang tight a bit longer.

18z NAM-NEST shows very light total precip west of Philadelphia by 7 PM. 0.01 to 0.02 inches of water. (Click on image for a larger view.)

Previously Posted Sun @ 4:38 PM — —A trend towards milder weather this week has been well-advertised. As we saw about two weeks ago, the AI models are forecasting highs to be somewhat higher than the operational models.

First, here’s what’s happening now, Sunday afternoon—

Current satellite water vapor image with superimposed RAP model Mean Sea Level Pressure isobars (black contours) potential vorticity (fine violet/yellow contours) with superimposed MRMS RADAR. (Click on image for a larger view.)

Monday will be windy and gusty in the afternoon, ahead of a weak front.

The low pressure system in Canada (L) will move rapidly eastward and a front will develop to our west associated with that northern system on Tuesday with clouds and some showers possible mid afternoon according to the GFS and NAM-NEST.

02-23-25 12z GFS forecast for Tuesday at 3 PM. (Click on image for a larger view.)

It will briefly colder Tuesday night, but temperatures partly rebound on Wednesday.

Here’s the NBM temperature meteogram, for Blue Bell, showing its high temperatures (TMAX)—

12z NBM high temperatures, temperatures and dewpoints for Blue Bell PA (Click on image for a larger view.)

The new ECMWF-Single AI model shows these highs—

12z ECMWF Single (AI) forecast temperatures at 1 PM. The free version does not offer a TMAX, and it’s every 6 hours, so you don’t see the high temperature at 3 PM; You can probably add at least two degrees to its temperatures shown. (Click on image for a larger view.)

By Thursday afternoon, another stronger cold front is expected to move through with some rain—

A cool down for Friday and another cold weekend follows, but then a big warmup for the first week in March.

Philadelphia Area Weather Forecasts

WEEKEND WEATHER FORECAST

#Philadelphia #weather #PAwx

A simple forecast for this weekend. High pressure generally in control with moderating temperatures. A few disturbances in the upper atmosphere will pass through both Saturday and Sunday afternoons with some increased cloudiness.

Here’s the water vapor image from this afternoon—

Current satellite water vapor image with superimposed RAP model), Mean Sea Level Pressure isobars (black contours) potential vorticity (NAM and GFS) (fine violet/yellow contours) with superimposed MRMS RADAR. (Click on image for a larger view.)

Saturday Forecast

Sunny in the morning with sunshine through high level clouds in the afternoon. Still somewhat windy/breezy.

NBM high temperatures: Blue Bell, PA 40º Philadelphia, PA 41º
Low uncertainty (based on standard deviation): ± 1.1º

Sunday Forecast

Similar forecast to Saturday. Sunny in the morning, sunshine through high cloudiness in the afternoon.

NBM high temperatures: Blue Bell, PA 44º Philadelphia, PA 46º
Low uncertainty (based on standard deviation): ± 1.0º

The ECMWF has released a new AI model, called the AIFS -Single. I’ll be adding this to the multitude of models I use to create my forecasts in the coming days.