Daily Archives: Sunday, March 29, 2026 4:39 pm

Philadelphia Area Weather Forecasts

THIS WEEK’S WEATHER

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Friday Update

Posted Thursday 04/02/26 @ 6:02 PM — We didn’t get anywhere near the NBM forecast high of the 50s today. We stayed in the mid-40s.

Drizzle and light rain have developed and will continue through much of the night. Some showers are forecast to move in about 1 AM, mostly west of the immediate city.

Water Vapor image at XX with superimposed RAP model MSL pressure (black contours), GFS/NAM potential vorticity contours (yellow & violet fine contours) with MRMS Radar and surface wind barbs, I’ve drawn in the location of the warm front. The green arrows show the expected path of the showers currently in West Virginia- Most of the showers will stay west of the city at 1 AM. . (Click on image for a larger view.)

The latest RRFS still shows sunshine through thin cirrus by about 12-1 PM Friday, earlier west and south. The NAM-NEST is somewhat later, about 3 PM. I’m going with the RRFS.

Stationary Front–> Warm Front

Posted Thursday 04/02/26 @ 9:04 AM — Today, Thursday, we have a classic setup of a stationary front just to our south with moisture over-riding the front from the south and west. This front will transition to warm front today and move north us Friday morning. (It should be pointed out that the timing for a warm front passage is often less than precise.)

Current Water Vapor Image—

Current satellite water vapor image with superimposed RAP model 500-1000 mb thickness lines (yellow), jet level wind streamlines (orange contour-arrows) potential vorticity (fine violet contours) and superimposed MRMS radar. The stationary front to our south will transition to a warm front and move north later today. (Click on image for a larger view.)

Temperatures today will be in the mid 50s by afternoon according to the NBM.

As the warm front begins to move north later this evening, some showers and thundershowers are likely after midnight into early Friday morning (2 AM). These are not expected to be strong or even severe, but the models sometimes underestimate night-time warm fronts. I’ll update later if things change.

According to the latest RRFS, the low clouds transition to sunshine through high clouds between 12 PM and 1 PM on Friday—

06z RRFS cloud cover at 1 PM Friday. Blue=low clouds, maroon=mid-level clouds, tan = high cirrus clouds (Click on image for a larger view.)

While today (Thursday) will be chilly with an easterly flow off the ocean, Friday will become much warmer.

Saturday looks very nice. Rain on Easter Sunday.

An Interesting Set-Up

Posted Wednesday 04/01/26 @ 8:06 PM — The front dropped through from the north this afternoon and is just south of the Philadelphia area, as shown by the latest RTMA wind streams at 7:30 PM EDT—

23:30z RTMA Blue line shows the wind convergence at the surface of winds from the northeast, behind the front, and winds from the southwest just ahead of the stalled front. (Click on image for a larger view.)

The latest hourly RAP model shows winds at 10,000 feet riding over the stalled front, almost as a warm-front scenario—

Radar and superimposed RAP model winds at 10,000 feet (700 mb) and vertical motion -Omega (fine green lines) Moisture aloft is riding up over the edge of the front at the surface. (Click on image for a larger view.)

As forecast, shower and thunderstorms will move in by 10 PM, but it appears it may be earlier as the moisture aloft rides over the frontal boundary at the surface. Omega values are moderate (8-10) so I expect the rain and storms to hold together. BUT, despite the Severe Thunderstorm warnings, I don’t expect this activity to be in the truly severe category. As shown, it will be scattered. Not all areas will be affected. Southern areas (S NJ- Delaware have the highest chances.) (Disclaimer— all thunderstorms have dangerous lightning)

Wednesday Thursday Forecast Update

Posted Wednesday 04/01/26 @ 8:12 AM — A very warm southwesterly flow ahead of a sagging cold front will bring sunny skies and very warm temperatures today. Highs 83º-84º. It will also be somewhat windy.

The cold front moves through about 8 PM today with a few showers and storms. Again, I don’t see much severe weather from this front, but the NWS will likely issue a severe thunderstorm watch or warning, mostly for public safety reasons.

As the front moves through it will stall and winds will shift to the east northeast as high pressure remains to our north.

06z GFS forecast for 1 AM Thursday. Stationary front just ot our south with wave of low pressure riding along giving us rain late Wednesday evening into Thursday. (Click on image for a larger view.)

Of interest…a low pressure wave will develop along the stalled front and bring some heavier rain and possibly some thunderstorms about 11 PM to 1 AM Thursday morning. These storms look to have heavier rainfall than those with the actual front earlier in the evening.

With the easterly wind, low clouds and cooler temperatures are expected for Thursday.

Wednesday Forecast Update

Posted Tuesday 03/31/26 @ 5:56 PM — A cold front will sag through our area from the north later Wednesday into Thursday. The upper level dynamics (jet stream configuration and winds) aren’t favorable for organized severe or even very strong storms.

Scattered showers and thundershowers are possible both early morning and increasingly probable from early afternoon through Wednesday evening and night. Precipitable water is not all that high (1.2-1.3″) so heavy rain for an extended period isn’t likely. (I’m sure a severe thunderstorm watch or warning will be issued for some area though, despite the limited dynamics available.)

Highs tomorrow 83-84º in Philadelphia. There will be considerably more cloud cover on Wednesday compared to Tuesday.

18z NBM maximum Temperatures. Fine Black Contours are near ground (2m) temperatures in 1º increments. (Click on image for a larger view.)
Tuesday Update

Posted Tuesday 03/31/26 @ 9:36 AM — Today’s highs may reach the low 80s.

Today’s 12z NBM high temperatures + standard deviation at 3:30 PM Actual means are a bit lower. (Click on image for a larger view.)

Some scattered showers and thundershowers may break out north and west of the immediate city during the late afternoon and early evening. They are not expected to move into the city.

06z RRFS forecast for 8 PM . (Click on image for a larger view.)
Tuesday-Wednesday Update

Posted Monday 03/30/26 @ 5:43 PM — The mix of clouds and sun will continue through Wednesday. The jet stream is to our north and has a general anticyclonic flow. Low pressure to our west is sending weak disturbances but overall sinking air is preventing organized rain from developing.

Water Vapor image at 5 PM with superimposed RAP model MSL pressure (black contours), GFS/NAM potential vorticity contours (yellow & violet fine contours) with MRMS Radar and surface wind barbs, The jet stream is just north of the white arrows (just north of the potential vorticity contours) The general anticyclonic curvature (white arrows) is causing sinking air, interfering with large scale rainfall. The green arrows depict the flow of disturbances into our area from the west. (Click on image for a larger view.)

Some light sprinkles are expected tonight, after midnight, mostly north of our area.

On Tuesday, more sunshine and clouds. The latest RRFS has some showers about 8 PM somewhat far north of the city. The Model Blend has these showers into Philadelphia. Too soon to see which is correct.

18z RRFS forecast for 8 PM Tuesday. Simulated radar with clouds Blue=low clouds, maroon=mid-level clouds, tan = high cirrus clouds (Click on image for a larger view.)

Wednesday looks very warm (low 80s), mostly sunny with periods of clouds. Some heavier rain moves in mid-evening hours.

Originally Posted Sun 4:39 PM —High pressure that gave us fair skies and cool windy conditions over the weekend will drift to our east. Low pressure in the central US will move northeastward with an associated warm front. Most of the showers associated with this front will occur to our far north.

ECMWF-AI forecast for Tuesday . Warm front will be north of our area with a few light showers early Tuesday morning. Sun breaks out Tuesday afternoon. More cold air attempts to move in late Wednesday into Thursday and Friday. (Click on image for a larger view.)

Monday – Periods of clouds and sun. A few light showers possible mid afternoon. Highs near 73º

Tuesday- showers associated with the warm front early morning and to our far north. Skies clear for some sun and milder temperatures. Highs 81º.

Wednesday- A cold front approaches. Showers and thunderstorms possible. Highs 81º

Thursday-Saturday- Cooler. The front may stall giving us rain.