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Philadelphia Area Weather Forecasts

WEEKEND WEATHER FORECAST

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#Philadelphia #weather #PAwx #PhillyWx

Sunday Forecast Update

Posted Sunday 04/19/26 @ 11:17 AM — The latest RRFS shows the rain to have exited the area by 2 PM

12z RRFS forecast for 2 PM Sunday (Click on image for a larger view.)

Posted Sunday 04/19/26 @ 10:31 AM — The cold front went through our area before daybreak as forecast. This cold front is what is called an “anafront“. Unlike most cold fronts, where the rain precedes and accompanies the front, an anafront has the warm air rising over the cold air wedge, causing rainfall to fall significantly behind the actual frontal passage.

Current water vapor and radar with superimposed RAP model parameters. The front is well off the coast, but the rain is approaching our area behind the front. (Click on image for a larger view.)

The rainfall is moving to the northeast as the main line of rain slowly moves eastward. The models have revised the total rainfall lower as most of the energy driving the showers moves off to the northeast before it gets here. Total rainfall is likely to be less than 0.20″ in the general Philadelphia area.

This event again captures a tendency towards drought-like conditions for our area, especially for the immediate PHL area and S. Jersey. Regular readers to this site know I’ve been talking about this developing dry pattern over the past month or two.

Weekend Forecast Update

Posted Saturday 04/18/26 @ 10:01 AM — Low clouds lifted a few hours ahead of what had been forecast. Mostly sunny for the rest of Saturday.

For Sunday, rain begins somewhat later than previously forecast, now about 8-9 AM. Rainfall amounts will be somewhat lower than forecast yesterday. Total rainfall about 0.3″. High wind gusts around 10-11 AM!

Rain ends and clouds lift between 3 and 4 PM Sunday.

A Quick Update

Posted Friday 04/17/26 @ 6:09 PM — Some areas saw showers Friday afternoon. Some additional activity may move into our area over the next hour or so. There is some strong support near Philadelphia and just east. We’ll see if they hold together.

Radar at 6 PM Strong area of vertical motion (light yellow contours) just southeast of Philadelphia. With daytime heating waning, we’ll need to see if thsese hold together.

Originally Posted Fri 4:55 PM —High pressure behind the front that broke our early Spring anomalous heat wave will move off to our northeast. An easterly flow will keep temperatures cooler on Saturday. A strong cold front moves through Sunday morning with some much-needed rain.

Saturday

High pressure departs and an easterly flow of air will bring low clouds in the early morning. These dissipate by late morning and we’ll have sunshine through high cirrus clouds. An easterly wind keeps temperature east of the city quite cool.

The winds increase from the southeast as a warm front approaches later Saturday night.

High Temperatures Saturday– warmer further west from the shore—

NBM highs at 4 PM Saturday. Warmer to the west. (Click on image for a larger view.)

Sunday

Cloudy with rain as a cold front moves through the area. Rain begins before daybreak. It becomes windy and gusty by late morning as the cold front moves through. There’s a chance of a thunderstorm embedded in the showers. Currently, about 0.5 inches of rain is expected. Rain ends and skies gradually clear by late afternoon.

Temperatures drop behind the cold front and remain in the 60s falling later in the day. It will be windy.

ECMWF-AI forecast for 8AM Sunday Cold front advances with a dip in the jet stream.. Temperatures drop and winds increase with the front. (Click on image for a larger view.)
Philadelphia Area Weather Forecasts, PHL Climate Forecasts

WEEKEND WEATHER FORECAST

#Philadelphia #weather #PAwx #PhillyWx

Rain Outlook?

Posted Saturday 04/11/26 @ 9:11 AM — You’ve already heard what a nice weekend we’ll be having. What can I add?

Well, as mentioned over the past week or so, I’m seeing a pattern of very dry weather for our area over the coming months.

The latest ECMWF-AI will be used to illustrate and the pertinent information is in caption below —

06z ECMWF-AI forecast for Thursday. The shading shows the Total precipitation through 2AM Thursday. The path of the rain (green arrows) follow a path that takes it around our area, not through our area.

Notice the contour (faint gold color) that extends and pushes in to our area. That contour is a 500-1000mb “thickness” line— it captures the 3-D shape of the air mass over us in the lower half of the atmosphere. . Most important is the sharp anticyclonic curvature of the line right over us. This anticyclonic curvature is associated with downward motion; rain/showers that move towards this area will fall apart. (Click on image for a larger view.)

Continuing from the caption above, as long as this sharp, anticyclonic curvature remains over our area, rain and thunderstorms will be inhibited. We’ve seen this exact same process in recent past summers during what became drought situations. The best we’ll see with this setup are thunderstorms that fall apart as they approach and rain areas that become very light and scattered.

This pattern of rain ‘avoiding’ our area has been happening for quite awhile. These patterns certainly can change. If it’s part of a recognized climate pattern called the Madden-Julian Oscillation, it could easily last 3 months or more. I’m not liking what I’m seeing.

Weekend Early Edition – Beautiful Weekend

Originally Posted Fri 9:57 AM —A weak front, currently just northwest of Pennsylvania, will pass through about 5 AM Saturday morning. The rain associated with this front will shear off to our northwest. A few very light showers possible northwest of the city around midnight with this front. A negligible amount of rainfall.

Current satellite water vapor image with superimposed RAP model 500-1000 mb thickness lines (yellow), Mean Sea Level Pressure isobars (black contours) and radar. (Water Vapor Imagery reveals emitted water vapor infrared TEMPERATURE, NOT REFLECTED LIGHT from CLOUDS.) (Click on image for a larger view.)

High pressure builds in behind the front this weekend. Windy Saturday morning, then winds subside in the afternoon. Sunny with very light winds on Sunday. Highs 64º-68º Saturday and 69º-70º on Sunday. :

Another system comes through Monday. Rainfall again will stay far north and west of the city and South Jersey. We may see some scattered very light showers close to the city.

As I discussed last week, I see signs of a very dry pattern for our area in the extended range forecasts.

One more thing…

With a very dry pattern developing, I expect to see increasingly frequent wildfires forming with smoke issues affecting many areas in the coming months. Here’s the current HRRR smoke model showing wildfires and sources of smoke in the continental US—

12z HRRR smoke model shows sources of smoke- wildfires, other sources. (Click on image for a larger view.)


Philadelphia Area Weather Forecasts

WEEKEND WEATHER FORECAST

#Philadelphia #weather #PAwx #PhillyWx

Sunday Forecast Update

Posted Sunday 04/05/26 @ 8:56 AM — I’ve been having fun working with Anthropic’s Claude AI to create specialized derived data from the RRFS model data input. As an experiment today, the “500mb Dynamic Forcing” shows some reasonably hefty triggers (orange below) for strong storms in the white box below.

10z RRFS shows two areas of significant “forcing”-(orange) dynamics that trigger strong upward motion. The strong storms occur northeast of the maxima (orange) along the 500mb wind streams. Just an experiment. (Click on image for a larger view.)

Posted Sunday 04/05/26 @ 8:22 AM — The cold front is just to our west and the models continue to forecast about a 4 hour period of rain, beginning about 11:30 -noon (Blue Bell) and about an hour earlier in western Montco/Bucks/Chester counties.

Current satellite water vapor image (8 AM) 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. (Click on image for a larger view.)

Looking at the latest models, I don’t see any severe weather for our area today, but the front may pick up some energy by the time it reaches the Jersey shore later in the afternoon.

Sun 8:19 AM —Forecast Review — The warm front was supposed to be north of our area last night, but it became a backdoor cold front as high pressure pushed it south and a cooler easterly flow was with us, causing the early morning fog. The warm front is finally moving north of our area again as I write this and winds are shifting to the southwest ahead of the approaching strong cold front.
Saturday Forecast Update

Posted Saturday 04/04/26 @ 8:36 AM — A weak ‘cold’ front (wind shift) moved through over night and winds have shifted to the north.

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.
(Click on image for a larger view.)

The weak boundary will return as a weak warm front again this afternoon and evening. Some scattered showers, perhaps some thundershowers will break out about 3-7 PM, mostly south and then west of the city. Exact placement not possible. The front will continue to move north over night with additional scattered showers .

4 PM Saturday—

06z RRFS with drawn warm front position at 4 PM (Click on image for a larger view.)

As a result, high temperatures will be pleasant and closer to 78-79º instead of the 80s previously forecast.

No change in Sunday’s forecast at this time.

Weekend Forecast

Posted Friday 04/03/26 @ 4:59 PM — With the warm front having moved north of our area, weak high pressure will be in control for Saturday. A cold front moves through about 2 PM on Sunday.

Saturday Forecast

Fog around daybreak, then becoming sunny. While high pressure will be in control, some upper level weak disturbances may set off some light scattered showers between 3 PM and 5 PM on Saturday. Mostly sunny but some clouds at times.

High Temperatures Blue Bell, 81º Philadelphia 83º Above average uncertainty with a sd of ± 3.3º

Sunday Forecast

Some sunshine early, the cloudy by 10 AM. It will be windy. Showers and possibly some thunderstorms move through between noon and 3 PM. I don’t see much in the way of severe weather.

18z RRFS 1 hour accumulated rain at 1 PM Sunday. (Click on image for a larger view.)

Temperatures peak in the morning and fall during the afternoon and evening. Highs 71 Blue Bell, 73º Philadelphia Above average uncertainty of ± 3.3º

Weekend Preview

Posted Friday 04/03/26 @ 4:56 PM — High temperatures were in the upper 60s on Friday, closer to the ECMWF-AI forecast and quite a bit lower than the forecast by the new NBM.

Originally Posted Fri 11:19 AM —The warm front will move north of us today. There should be clearing about 1 PM southwest and west of the city, and between 2-3 PM in Philadelphia.

Current warm front position at 10:15 AM—

Approximate Warm Front Position at 10:15 AM Friday. Despite my attempt to draw the position, warm fronts are not as distinct as cold fronts. (Click on image for a larger view.)

It should be noted that the NBM has highs near 79º by late afternoon, while the ECMWF-AI has the warm front passage slower and keeps us only in the upper 60s. to near 70 in South Jersey. The latest RRFS confirms this, with highs just reaching 70 into KPHL airport.

Saturday should be sunny and warm., Highs upper 70s to low 80s.

Sunday rain begins in the morning and continues into the afternoon. More about this later today.