Philadelphia Weather Outlook

THIS WEEK’S WEATHER

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Posted Wednesday 10/01/25 @ 8:10 AM — The cloud cover associated with the tropical systems has departed and high pressure will bring cool weather and sunny skies.

06z GEFS shows high pressure to our north and a cold front approaching in the upper Plains with some cloudiness in the upper Midwest. The red line is the 500-1000 mb ‘thickness line’. Indicating a cold air mass in Northeastern Canada. (Click on image for a larger view.)

A ‘dry’ cold front in the upper Midwest will bring some cloudiness mixed with sun Thursday and Friday Continued dry conditions!

Posted Tuesday 09/30/25 @ 8:46 AM — The outflow moisture of Imelda will continue to cause cloudiness in our area through much of Tuesday. Rain associated with this moisture flow is hitting a rather strong high pressure ridge over us (1022 mb) and is dissipating to our south.

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 MRMS RADAR. Water Vapor Imagery reveals emitted water vapor infrared temperature, NOT reflected light from clouds as is the case with visible satellite imagery. (Click on image for a larger view.)

The mid and high level cloudiness should thin out to just sunshine through high clouds mid-afternoon Tuesday.

Originally Posted Sun 5:51 PM —This week will be another good time for local meteorologists to take a vacation. High pressure will build down from the northeast, blocking the tropical system’s movement northward towards us and giving us dry conditions through at least next weekend!

Until that time, high pressure system builds southward with a front late Tuesday, and moisture outflow from the tropical systems will bring significant cloudiness both Monday and Tuesday. Skies clear Wednesday with temperatures cooling down.

Here’s the European AI model (ECMWF-AI) forecast for early Wednesday, with colorized high pressure (blue) and low pressure (pink)—

12z ECMWF-AI surface forecast for 2 AM Wedmesday with colorized surface pressures (Click on image for a larger view.)

The statistical ensemble model, the NAEFS, shows zero chance of rain here through Oct 7th!