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Rain Storms Update

Posted Sunday 03/22/26 @ 8:19 PM — Based on the latest radar and RAP model fields, the storms to our north and west will move in over the next hour or so. The RAP data suggests the storms may intensify as they move closer to our area.

The rain continues until about 6-7 AM, as this system is slow to move through. Clouds linger well into Monday.

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Rain – Thunderstorms Sunday Evening

Posted Sunday 03/22/26 @ 9:22 AM — In recent days, the onset of the rain and thunderstorms associated with an advancing somewhat backdoor cold front has varied from late afternoon to late evening. The models seem to have come together with the line of showers and embedded thunderstorms reaching northwestern sections of Montco and Bucks counties by 8 PM and areas closer to the city by 9 PM or so.

Currently, the front is draped across NY state—

Here’s the HRRR “simulated radar” forecast at 9 PM—

With the somewhat later arrival, of the main line of rain, severity of any thunderstorms is lowered at this time.

Expected high temperatures for today have been reduced but with high uncertainty of ± 3.5º likely due to cloud cover uncertainty—

Low pressure is expected to form along the slowing front near the Delmarva area, prolonging rainfall into early Monday morning (7-8 AM.)

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Forecast Update

Posted Saturday 03/21/26 @ 11:34 AM — A quick update. Based on the latest NBM, it appears that the showers move in Sunday earlier than previously forecast. Showers as early as 4:30-6 PM near the city.

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Posted Saturday 03/21/26 @ 8:59 AM — Going back to last night’s models, all seem to have underestimated the fog that has formed in some areas Saturday morning.

(My “go-to” model, the new RRFS, has been unavailable, having suspended its pre-release runs Friday morning and it remains unavailable at this time. Perhaps it’s being prepared for parallel release on NOMADS, or perhaps this is one of its frequent suspensions for shifting between the different supercomputers called “Dogwood” and “Cactus”. )

It’s expected that the sun will break out this morning and remain sunny for most of the day Saturday. Highs 62º-65º

The showers and possible thunderstorms Sunday evening may have shifted closer to midnight. Highs on Sunday still 76º-78º

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Originally Posted Fri 7:12 PM —A weak cold front moves through Friday night. Rain associated with this weak front exits before daybreak Saturday. Following a warm-up on Sunday, another stronger cold front moves through Sunday evening with more showers and possibly some thunderstorms.

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