Monthly Archives: February 2025

Philadelphia Area Weather Forecasts

WEEKEND WEATHER FORECAST

#Philadelphia #weather #PAwx

Posted Sunday 02/16/25 @ 8:56 PM —The well-advertised storm expected for Wednesday into Thursday looks to only brush the Philadelphia area with possibly 1-2 inches of snow. Areas near the Jersey shore may see substantial snow, based on the current track. Updates tomorrow!

Sun 8:46 PM —Forecast Review — We had the rain and we have the winds! Here’s the MRMS total rainfall (and snow-water equivalent) over the past 48 hours—
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 RTMA is a real-time data model run every 15 minutes, reporting for the previous 15 minutes. Here’s the wind gusts it’s showing at 8:15 PM—

RTMA showing winds and wind gusts at 8:15 PM tonight. (Click on image for a larger view.)

Sunday Forecast Update

Posted Sunday 02/16/25 @ 2:35 PM — Based on the latest radar, satellite and HRRR hourly data, it doesn’t appear that we’ll see those near 60º temperatures forecast by the models yesterday. (Some areas in South Jersey may see those highs about 3-4 PM)

The cold front is in central PA at this time. Some additional showers may accompany the actual frontal passage around 3:30 PM-5 PM.

Latest HRRR 3 hour pressure change (green contours) with superimposed radar and visible satellite image. Some of the precip in Pittsburgh may be snow showers. (Click on image for a larger view.)
Sunday Forecast Update

Posted Sunday 02/16/25 @ 9:23 AM — The latest NBM and HRRR show the heaviest rain to occur here between 12 PM and 3 PM. Here’s the latest HRRR—

Today’s 12z HRRR forecast for 1 PM today. Actual cold front still in central PA at that time. The front is expected to move through here with plunging temperatures and high winds 4-5 PM

Total additional rainfall about 0.45- 0.65″ Wind gusts as high as 40-50 mph between 3 PM and 6 PM and continuing gusty. Rain tapers off and ends about 5- 6 PM or so.

I’m keeping an eye on the potential storm late Wednesday into Thursday. It still appears to have a track too far south for heavy snow here, according the the AI models. Still much uncertainty.

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Forecast Update

Posted Saturday 02/15/25 @ 9:32 PM — Tonight’s models show some changes in the Sunday forecast—

  • Total rainfall will be closer to 1 inch or less instead of 1-2 inches.
  • Winds will increase significantly during the afternoon and evening.
  • The most likely time for thunder is about 2-3 PM.
  • The heaviest rain will fall 1 PM to 3 PM.
  • Rain ends by 4:30-6 PM.
Active Weather Pattern

Posted Saturday 02/15/25 @ 5:38 PM — The heaviest rain will be arriving after 9 PM tonight and continue through the night. There may be a break in the rain Sunday morning (8 AM- Noon), following the passage of the warm front. Rain returns by the early afternoon and continues ahead the approaching cold front.

Expect some thunderstorms and very gusty winds in excess of 40 mph. ahead of the cold front on Sunday. The cold front moves through between 4 and 6 PM. Total rainfall for this storm is still expected to be in the 1.5″ range.

Very cold weather returns for next week, as the storm track moves to our south.

A possible significant snow storm for us is forecast for late Wednesday into Thursday.

While the AI models are suggesting much of the snow might miss the Philadelphia area, mostly affecting South Jersey, However the operational models (GFS, ECMWF, Canadian GEM) are forecasting a potential 6+” snowfall for us. Too soon to hang your hat on this forecast.

Here’s the ECMWF for next Thursday—

02-15-25 12z ECMWF forecast for Thursday at 7 AM. (Click on image for a larger view.)
Snow and Rain on the Way

Posted Saturday 02/15/25 @ 10:27 AM —The models, not unexpectedly, are leaning towards less snow/sleet accumulation. The precip is on our doorstep, but a dry lower atmosphere will maintain the 12 PM – 2 PM start time

MRMS and NEXRAD combined radar with RAP model Omega (Click on image for a larger view.)

Here’s the latest NBM snow/sleet accumulation—

Today’s 13z NBM snow accumulation. Most of area will see close to nothing or a coating except northwest suburbs. (Click on image for a larger view.)

Total rainfall for the weekend will be about 1.3″-1.5, although some models have close to 2+” in some areas.

Today’s 13z NBM total rainfall for the entire weekend. (Click on image for a larger view.)
Starting as Snow

Posted Friday 02/14/25 @ 9:39 PM — More models have a forecast of snow accumulation prior to a changeover to rain late afternoon Saturday or Saturday early evening.

The latest HRRR has minimal snow accumulation. The model blend (NBM) is still cranking out accumulating snow, despite temperatures rising above freezing near the surface.

Here’s the latest NBM snow accumulation forecast—

Tonight’s 01z NBM forecast snow accumulation by 6 PM Saturday. (Click on image for a larger view.)

When it comes to snow, long-time readers of this blog know I can’t ignore the NAM. The NAM is forecasting an unreasonably large snow accumulation—

Tonight’s 00z NAM shows an UNLIKELY snow accumulation for Saturday afternoon. Still something to ponder. (Click on image for a larger view.)

Snow moves in about 12 noon to 2 PM, a bit earlier in far western suburbs.

Not mentioned earlier is the considerable rainfall we’ll receive this weekend. Most models are in the 1.3″-1.5″ water range.

Wet and Windy Weekend

Low pressure developing in the central US will move north towards the Great Lakes and will bring rain to our area Saturday, beginning around 12 PM – 2PM as some accumulating wet snow and then transitioning to all rain by 5 PM, if not sooner.

Rain continues Saturday night through much of Sunday, as a secondary low pressure system develops off the NJ coast on Sunday.

WV image Friday at noon showing large system moving towards the Great Lakes with a strong subtropical jet stream adding moisture to the mix. (Click on image for a larger view.)

Saturday Forecast

Cloudy with wet snow or rain mixed with snow developing by 12PM to 2 PM The latest NBM shows some accumulation, but I think it may be over-done a bit. (The latest GFS shows somewhat more snow)—

19z NBM snow accumulation, possibly over-done. I calculate these NBM totals and my algorithm doesn’t include melting and compaction, which is going to be severe here. That said, the latest GFS has about 1.5 inches where I show 0.5 inches. (Click on image for a larger view.)

NBM high temperatures: Blue Bell, PA 38º Philadelphia, PA 41º
High Uncertainty (based on standard deviation): ± 2.4º

Sunday Forecast

Continued cloudy with rain. Quite warm but very windy! Possibly a thunderstorm ahead of a cold front. Temperatures fall following the cold front Sunday late afternoon into the evening.

NBM high temperatures: Blue Bell, PA 61º Philadelphia, PA 58º
Average Uncertainty (based on standard deviation): ± 1.6º

Philadelphia Weather Outlook

THIS WEEK’S WEATHER

#Philadelphia #weather #PAwx

Clearing Today – Cold Friday- Snow Saturday

Posted Thursday 02/13/25 @ 8:47 PM — Accumulating snow on Saturday afternoon looks less likely. Possibly a coating in northwest suburbs before a changeover to rain.

Posted Thursday 02/13/25 @ 9:28 AM — Several large shifts in temperature and weather over the next several days.


Today (Thursday) — Clearing around 2-3 PM and becoming windy and gusty. Mild but temperatures chill down later today and tonight.

Friday (Super Bowl Parade) — Sunny breezy and cold.

Saturday— Snow develops in the morning from west to east. Precip changes to sleet, then rain early evening hours. Preliminary snow accumulation (GFS model) about 1-3 inches mostly from the city north and west.

Today’s 06z GFS forecast for 5 PM Saturday showing precipitation type (PTYPE) (violet= snow) surface temperature (white contour) and low level vertical temperatures (magenta, purple contours) Shading is PTYPE; it does NOT indicate the exact coverage or intensity of the precipitation at that time. (Click on image for a larger view.)
Wednesday Night through Friday

Posted Wednesday 02/12/25 @ 5:13 PM — Our next in a series of disturbances is approaching and should be here by 6 PM -8 PM—

MRMS radar around 5 PM with superimposed RAP model 700 mb winds and Omega (Click on image for a larger view.)

Temperatures in most of the region will be above freezing, but some of the earliest precip may begin as light snow, quickly changing to rain.

NBM temperature and precipitation type at 8 PM Wednesday evening. White contour is 32º line (Click on image for a larger view.)

Total rainfall is expected to be about 0.45 to 0.65″ tonight with higher amounts in South Jersey and near the coast.

Thursday: Cloudy in the morning, then sunshine breaks out in the afternoon. Windy and gusty with highs in the low 50s!

Friday: The Super Bowl Parade will have sunshine and breezy conditions. High temperatures will be near 37º in the city.

Rain Wednesday night

Posted Wednesday 02/12/25 @ 9:44 AM — The models maintain cloudiness for us today, Wednesday. Many models crank out some very light snow or flurries beginning in the afternoon. (Temperatures in the upper atmosphere remain cold enough for snow from the city northwestward despite temperatures moving above freezing for much of the area.)

NBM precipitation Type at noon Shading doesn’t mean it’s snowing or raining, just the conditional probability of snow or rain in an area at this specific time.. (Click on image for a larger view.)

As another area of low pressure slides towards us, temperatures at all levels will rise above freezing. Total additional rainfall about 0.30″-0.40″ water by Thursday 8 AM.

Wed 9:23 AM —Forecast Review —The immediate Philadelphia area received slightly more precipitation in the form of snow than forecast below by the NBM . Areas to the west and north received slightly less than forecast. Areas in NJ received somewhat more than forecast. Overall, the forecast was fairly good.

Here’s the MRMS precipitation estimate for the past 24 hours given in inches of water. Based on actual measurement, multiply by 8-10 to get approximate snow depth.

MRMS rain-gauge measured rainfall combined with rain-gauge calibrated and interpolated radar-based summary of ACTUAL PRECIPITATION RECEIVED. Color shading is in inches. Line contour numbers are in mm. (25.4 mm= 1 inch)       (Click on image for a larger view.)

Measured snow totals from the NWS–

...Bucks County...
Levittown                    3.5 in    0548 AM 02/12   Trained Spotter
2 ESE Newtown                2.5 in    0634 AM 02/12   Other Federal
1 NNW Langhorne              1.8 in    1130 PM 02/11   Trained Spotter
Upper Southampton Twp        1.6 in    1250 AM 02/12   Trained Spotter
Plumstead Twp                1.6 in    0430 AM 02/12   Trained Spotter
Bensalem                     1.5 in    1024 PM 02/11   Public
Fricks                       1.5 in    0709 AM 02/12   Trained Spotter
Furlong                      1.0 in    1230 AM 02/12   Trained Spotter

...Chester County...
East Nantmeal Twp            3.3 in    0700 AM 02/12   Trained Spotter
Berwyn                       3.2 in    1038 PM 02/11   Trained Spotter
West Chester                 3.1 in    0600 AM 02/12   Public
Jennersville                 2.7 in    0556 AM 02/12   Public
1 WNW Chesterbrook           2.7 in    0634 AM 02/12   Trained Spotter
West Caln Twp                2.5 in    0553 AM 02/12   Trained Spotter
East Coventry Twp            2.0 in    0530 AM 02/12   Public

...Delaware County...
Boothwyn                     3.7 in    0120 AM 02/12   Trained Spotter
Chadds Ford Twp              1.8 in    1000 PM 02/11   Trained Spotter

...Montgomery County...
Norristown                   3.1 in    0613 AM 02/12   Trained Spotter
Plymouth Meeting             3.0 in    0100 AM 02/12   Public
King of Prussia              2.7 in    0604 AM 02/12   Trained Spotter
1 E Willow Grove             2.5 in    0600 AM 02/12   Trained Spotter
Eagleville                   2.3 in    1200 AM 02/12   Public
1 NNE Willow Grove           2.0 in    1228 AM 02/12   Public
Eagleville                   2.0 in    0630 AM 02/12   Trained Spotter
New Hanover Twp              1.9 in    0500 AM 02/12   Trained Spotter
East Norriton                1.8 in    1100 PM 02/11   Public
1 ENE Plymouth Twp           1.6 in    1222 AM 02/12   Public


...Philadelphia County...
Philadelphia Intl Airport    3.1 in    0700 AM 02/12   ASOS
1 SSE Center City            3.1 in    0713 AM 02/12   Public
Bustleton                    3.0 in    0523 AM 02/12   Trained Spotter
Fox Chase                    2.9 in    0530 AM 02/12   Trained Spotter

Tuesday Snow Update

Posted Tuesday 02/11/25 @ 7:54 PM — Looking at the latest hourly models (RAP and HRRR), it appears that we may get even less snow than the recent NBM forecast posted. I see very little in the way of pressure falls off the coast and negative omega values are plentiful, meaning less dynamics to result in snow intensification.

The ‘heaviest’ snow (air quotes placed for a reason) is still forecast to occur between 9 PM and midnight, then taper and end around 3 AM.

Here’s the latest HRRR which shows additional snowfall from 6 PM onward—

HRRR 23z Additional snowfall from 23z (6PM) onward. Even this may be too high. (Click on image for a larger view.)

Posted Tuesday 02/11/25 @ 4:32 PM — Additional models have become available since my last update. Little has changed with total precipitation around the city ranging from 0.18″ to 0.28″ water equivalent. This translates into a similar snow forecast as described earlier.

Currently light precipitation has just begun to fall in our area. As expected, the main area of precipitation is south of our area. Evaluation of vertical upward motion (“Omega”) shows low pressure will develop far off the Delmarva coast in the area designated (L) . In our area, there are little signs of intensification, but area of strong vertical motion in West Virginia now will bring some heavier snow here about 11 PM or so.

Evaluation of vertical upward motion (“Omega”) shows low pressure will develop far off the Delmarva coast in the area designated (L) . In our area, there are little signs of intensification, but area of strong vertical motion in West Virginia (1) now will bring some heavier snow here about 11 PM or so. (Click on image for a larger view.)

Despite somewhat heavier snow forecast from the ECMWF, I’m sticking with the latest model blend (NBM)—

19z NBM Snow accumulation forecast by 7 AM Wednesday. (Click on image for a larger view.)

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