Daily Archives: Monday, February 10, 2025 9:42 am

Philadelphia Weather Outlook

THIS WEEK’S WEATHER

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Active Weather Pattern- Snow Likely

Posted Monday 02/10/25 @ 6:03 PM — The latest GFS, just available, shows some light snow/flurries early afternoon Tuesday, before the main area of snow moves in between 4-7 PM.

Posted Monday 02/10/25 @ 5:17 PM — A quick update on the expected snow for Tuesday evening. Here are the trends—

  • Light snow moves in about 4-7 PM from the southwest.
  • Total accumulations have moved somewhat lower than had been forecast this morning.
  • Snow tapers to flurries between 8 AM and 10 AM Wednesday.
  • Snow re-develops Wednesday evening, but changes to rain. Rain may be heavy.

Here’s the latest model blend snow accumulation forecast—

Today’s 19z NBM model (model blend) forecast snow accumulation by Wednesday morning. (Click on image for a larger view.)

Posted Monday 02/10/25 @ 10:06 AM — One more thing… Following a break in the precipitation on Wednesday morning and early afternoon, snow will redevelop Wednesday evening, but change to sleet and rain. Heavy rain expected into Thursday.

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Originally Posted Mon 9:42 AM —As mentioned last Thursday, an air mass boundary stretching across the country will be a focal point of low pressure development this week.

Here’s what it looks like on satellite water vapor imagery this morning—

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. A wave (1) has already developed expected to bring snow later Tuesday. An area of potential vorticity (2) will be focal point of the next wave of precip on Thursday. Warm moist air is streaming up from the southern jet stream. (Click on image for a larger view.)

Here’s what the corresponding ECMWF weather map looks like—

Current 06z ECMWF surface forecast for the corresponding WV image above. (Click on image for a larger view.)

Snow is expected to move in during the afternoon on Tuesday and continue through Tuesday night.

ECMWF forecast for 1 AM Wednesday morning. Snow shield just makes it north of Philadelphia. Notice critical thickness lines (red magenta, yellow) are all south of our area, assuring all snow. (Click on image for a larger view.)

A large gradient of precip will set up, north to south, affecting snow totals. Small variations in the intensity and track of this storm will create large uncertainties in actual snow totals.

It should be noted that the AI version of the ECMWF has very little snow for us with this storm. So there’s high uncertainty with this forecast.

The NBM has been doing well with recent snow/sleet forecasts. Here’s its snow total forecast by Wednesday morning at 8 AM —


Latest NBM (13z) snow totals by Wednesday 8 AM (Click on image for a larger view.)