Philadelphia Area Weather Forecasts

WEEKEND WEATHER FORECAST

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Sun 4:56 PM —Forecast Review —The much-needed rainfall occurred as forecast with the higher amounts occurring north of our immediate area.
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)      (Click on image for a larger view.)

The RRFS was good with timing of the sunshine breaking through this afternoon.

Forecast Update

Updated Saturday 04/25/26 @ 11:12 PM — Latest models now show some clearing a bit later, about 3PM.

Updated Saturday 04/25/26 @ 9:20 PM — The rain will be ending from west to east about 3 AM Sunday morning. Low clouds in the morning thin for sunshine by early afternoon, sooner north and west. Windy conditions slowly subside during the afternoon.

Significant Forecast Change

Posted Saturday 04/25/26 @ 7:50 AM — Last night, the models were predicting about 1 inch + of rain for our area. The trend (which is in-line with our increasing drought pattern) has moved towards about 1/3 of an inch or less.

RRFS forecast total rainfall by Sunday 5 AM. A significant decrease. (Click on image for a larger view.)

As mentioned yesterday, this is not a very moist system and the large precipitation amounts previously forecast was based on a great deal of energy causing lift.

Unfortunately, this energy is looking much lower and its influence will be in the the NYC area and northward.

Water Vapor image at 8AM Saturday with superimposed RAP model MSL pressure (black contours), GFS potential vorticity contours (violet fine contours) with MRMS Radar and surface wind barbs, The purple box shows a small area of potential vorticity, the “energy” that had been forecast to cause some heavy rain here. That area is small now and moves north of us, according the jet flow wind direction. (Click on image for a larger view.)

It should be noted that many models were trending towards a northern track of the heavier rain over the past two days.

Some showers are right on our doorstep at 8 AM, moving into an area of supportive upward vertical motion—

Radar at 8 AM with Omega (vertical motion) yellow contours and 700 mb winds (green contours) (Click on image for a larger view.)

While some showers are possible this morning, most of the rain will fall after 4:30 PM into the night.

Sunday should be cloudy, but dry.

Originally Posted Fri 4:47 PM —A complex and energized system in the Midwest will push its moisture east towards us this weekend. Plenty of rain is possible with the timing now late Saturday into Sunday morning, a change from earlier forecasts.

WV at 5 PM Friday. Water Vapor image with superimposed RAP model MSL pressure (black contours), GFSbpotential vorticity contours (violet fine contours) with MRMS Radar and surface wind barbs, Plenty of energy with this system as it becomes negatively tilted. (Click on image for a larger view.)

Here are the current trends that have evolved since my posting last night. There are changes in the timing and and heavy rain banding.

  • The heavier rain for Saturday is delayed until the evening and night time hours.
  • The heaviest axis of rain will be a bit further north than forecast by the previous RRFS- heaviest rain in NYC
  • Two periods of rain are expected on Saturday, one beginning during the morning hours that will feature light scattered showers. Following a break in the action early Saturday afternoon, heavy rain will develop towards evening and continue through the night.
  • This is not an extremely moist system (Precipitable water about 1.3″). Any heavy rainfall will be the result of strong dynamics.

Saturday

A glimmer of sun early, then cloudy in the morning, light, scattered showers move in around noon. There may be a break in the action as most of the rain initially moves far north of our area. The rain restarts about 4-7 PM in our area and becomes rather heavy by midnight. The rain continues into Sunday morning. Windy and gusty.

High temperatures 54º Blue Bell, 56º Philadelphia. Higher than average uncertainty ± 3.0º

Sunday

Rain continues into Sunday morning, tapering off by early afternoon. There’s remains uncertainty at this time regarding the time the rain ends, with some models continuing it into early afternoon and some having it end mid-morning. VERY WINDY! GUSTS > 35 MPH.

High temperatures 52º Blue Bell, 52º Philadelphia. Higher than average uncertainty ± 3.3º

Another chance for rain on Wednesday next week.