Daily Archives: Sunday, March 23, 2025 4:25 pm

Philadelphia Weather Outlook

THIS WEEK’S WEATHER

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Wednesday through Saturday

Posted Tuesday 03/25/25 @ 6:04 PM — The fast moving low pressure system expected to form this evening will remain to our south. Rain may extend north into South Jersey, but the Philadelphia area will remain dry. Colder weather for Wednesday and Thursday with high temperatures around 50º with sunny skies. A warm up Friday. A big surprise for Saturday- high temperatures may approach 80º!

ECMWF-AI Temperature forecast for 2 PM Saturday! Contours are in 1º increments. (Click on image for a larger view.)

A rainy period develops Sunday into next Monday.

Winds Return for Tuesday

Posted Monday 03/24/25 @ 5:50 PM — Windy conditions, especially Tuesday morning, with gusts 25-30 mph. Highs return to about 57º-58º after a cold morning. Some clouds move in late afternoon.

Mon 5:47 PM —Forecast Review — The rain ended about 4 PM and some sun is breaking out as I write this. Total rainfall, was somewhat higher than forecast in areas east of the city.
MRMS rain-gauge measured rainfall combined with rain-gauge calibrated and interpolated radar-based summary of ACTUAL RAINFALL RECEIVED. Color shading is in inches. Line contour numbers are in mm. (25.4 mm= 1 inch)   It appears that there are some radar artifacts in this MRMS summary.    (Click on image for a larger view.)

Posted Monday 03/24/25 @ 8:58 AM — Based on radar and the latest HRRR, the rain will be ending about 2 PM-3 PM around Philadelphia and about 5 PM to 6 PM at the Jersey Shore. (The Canadian RGEM has the rain ending about 3-4 PM here with some sun possibly by 6 PM. )

Radar at 8:50 AM with superimposed RAP mode low level Omega (vertical velocity pressure). Some enhancement of the rain this morning around Philadelphia is expected with positive Omega. The entire line is moving to the east with the storms moving to the northeast. (Click on image for a larger view.)

As for that potential ‘experiment’ with the ECMWF-AI model, its forecast for some rain here is now late Tuesday night, with light rain ending for the daytime Wednesday. The GFS has moved closer to the ECMWF-AI with some rain in NJ late Tuesday night.

Originally Posted Sun @ 4:25 PM — —Low pressure and an associated cold front will move through on Monday. Rainfall looks to be in the 0.45″ range, but several models have as much as 0.75″ of rain falling over our area. Rain starts before daybreak Monday and continues through at least 4 PM, when any remaining precipitation will become light and widely scattered.

Overall, this coming week looks to be colder than recent weeks with a persistent dip in the jet stream over the Central and Northeastern US.

The current satellite water vapor image with superimposed RAP model parameters and MRMS radar shows the setup that will be persistent—

Current (Sunday afternoon) 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 MRMS RADAR. A persistent dip in the jet (white arrows) will be with us for most of the week. (Click on image for a larger view.)

Of interest is the energy in the Pacific Northwest diving southward into the upper trough. The latest ECMWF-AI model shows another storm developing Wednesday which lends itself to another “AI model Experiment“.

Basically this AI model shows much more development of this Wednesday low pressure system than the either the GFS or ECMWF—

Wednesday forecast from the latest ECMWF-AI-Single model. Much greater storm development than either the GFS or ECMWF (Click on image for a larger view.)

Yet another system associated with a warm front approaches Friday or Saturday. Temperatures look to moderate by next weekend.