Daily Archives: Friday, September 11, 2026 8:05 pm

Philadelphia Area Weather Forecasts

WEEKEND WEATHER FORECAST

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Sunday Forecast Update

Posted Sunday 09/13/26 @ 4:45 PM — A quick updat during the Eagles game. The showers are still forecast by this afternoon’s RRFS, but they appear unlikely. We do have some of the forecast cloudiness .

18z RRFS forecast for now. Only the stronger echoes to our south are showing up on radar. (Click on image for a larger view.)

Posted Sunday 09/13/26 @ 8:56 AM — The end of the rain is in sight and clouds will begin to break up for sunshine about 11 AM to 1 PM from west to east.

Water Vapor image at XX with superimposed RAP model Mean Seal Level pressure (black contours), 500-1000mb Thickness (yellow contours), RAP potential vorticity contours (violet fine contours) with MRMS Radar with surface wind barbs, Approximate position of cold front drawn in blue. (Click on image for a larger view.)

Despite earlier forecasts of sunshine during the Eagles games, the models continue to forecast a mid-level trough that will move through about 4 PM-7 PM with a few scattered and light showers and some patches of low clouds.

09z RRFS mid level trough axis (white line). Arrows show the 700 mb wind flow curvature around the trough. Simulated Radar shown. (Click on image for a larger view.)

Updated Saturday 09/12/26 @ 11:04 PM — Several of tonight’s models show some light shower activity during the Eagles game. Please don’t shoot the messenger.

Posted Saturday 09/12/26 @ 5:37 PM — The trend with today’s models continues with the previous forecast being mostly intact. A warm front is approaching, still some distance away to our south at this point in time—

Water Vapor image at 5 PM Saturday with superimposed RAP model Mean Seal Level pressure (black contours), 500-1000mb Thickness (yellow contours), RAP potential vorticity contours (violet fine contours) with MRMS Radar with surface wind barbs, I’ve drawn the approxiimate position of the warm front. (Click on image for a larger view.)

Here are the trends for tonight’s rain—

  • Light rain begins in Philadelphia as early as 11 PM but most likely in the midnight to 2 AM period.
  • Heaviest rain and potential thunderstorms between 6 AM and 10 AM Sunday. Most likely about 7-8 AM.
  • Some areas may have localized flooding, as “precipitable water” is in the high 2.2-2.3″ range.
  • Rain ends about 11 AM to 12 PM, earlier in western sections.
  • Mostly sunny by the kickoff of the Eagles, but there may be a few dark clouds lingering at times.

The axis of heaviest rain and storms will be where the highest dynamics and moisture convergence occurs. Here’s what’s predicted by the RRFS at 7 AM Sunday—

18z RRFS 850 mb moisture convergence (shading orange with black contours) and dynamic forcing (blue, red orange blotches) (Click on image for a larger view.)

Not surprising from the above, here’s the RRFS total rainfall forecast—

18z RRFS total rainfall forecast. (Click on image for a larger view.)

Originally Posted Fri 8:05 PM —Low pressure developing in the Mississippi Valley will move up towards us over the weekend. Rain and thunderstorms are not expected before the evening hours Saturday. The rain should depart mid to late morning, long before the Eagles game.

Water Vapor image at 7:30 PM Friday with superimposed RAP model Mean Seal Level pressure (black contours), 500-1000mb Thickness (yellow contours), RAP potential vorticity contours (violet fine contours) with MRMS Radar with surface wind barbs, Developing low pressure with plenty of moisture and energy. (Click on image for a larger view.)
Saturday

A warm front approaches during the daytime hours.

Sunshine through thin high cirrus clouds with an occasional period of cloudiness. Isolated showers move in from the southwest as early as 8PM but most models have the heavier rain and thunderstorms moving in from the west after 11 PM-1 AM

Highs (Model Blend): Blue Bell- 83 º Philadelphia 84º ± 2.8º Above average sd and and above average uncertainty. Increasingly windy in the afternoon from the SE.

Showers and some heavy thunderstorms after midnight. Total rainfall by Sunday morning about 0.8″-1.25″

Sunday

Showers tapering about 7-9 AM from west to east and ending by 11 AM. Then becoming sunny by late morning or noontime.

Windy in the morning, subsiding slowly during the afternoon. Winds shifting from WSW to WNW during the Eagles game.

Highs (Model Blend): Blue Bell- 83 º Philadelphia 85º ±2.9º Average sd and uncertainty.