Philadelphia Area Weather Forecasts

WEEKEND WEATHER FORECAST

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Rain Snow Update

Posted Sunday 02/15/26 @ 4:34 PM — At 4:30 PM, the precipitation is just southwest of our area and will move in as forecast between 5 PM and 6 PM.

The MRMS “hydrometeor” (rain, sleet, snow, ice) is showing a mix of snow and rain in areas where the models had forecast only rain at this time.

MRMS realtime hydrometeor classification Color key (BI: Biological scatterers (birds/insects) GC: Ground Clutter IC: Ice Crystals DS: Dry Snow WS: Wet Snow RA: Rain (light/moderate) HR: Heavy Rain BD: Big Drops GR: Graupel HA: Hail (often mixed with rain, noted as RH) UK: Unknown)

What we’re seeing now is a mix of dry snow, wet snow and melted snow (big drops), somewhat different than had been forecast.

Several models are forecasting temperatures as this time to be either too warm or too cold compared to the actual temperatures (RTMA).

The latest model blend hasn’t changed significantly over the past 24 hours. Here’s the latest median snowfall forecast—

19z NBM median Forecast Snowfall totals Median = Half the models comprising this ensemble are showing more than these values, half are showing less. (Click on image for a larger view.)

I’m going to throw in the 75 percentile range here—

19z NBM 75 percentile snow forecast. (75 percentile means 3/4 of the models comprising the NBM are forecasting up to this amount or less. The or less is important. Put another way another 1/4 of the models are forecasting above the median amount but less than this amount) (Click on image for a larger view.)

If the precipitation starts as snow instead of rain in your area, it’s likely the final totals will fall somewhere between the median and 75 percentile range. If it starts as rain, lean towards the lesser median.

Rain Snow Update

Posted Sunday 02/15/26 @ 9:41 AM — The models have settled on a low accumulation event with much of the area receiving only rain. Total precipitation forecast is 0.15-0.22 inches rain/snow-water equivalent. Temperatures in the upper half of the atmosphere supports frozen, but near ground temperatures and the lowest layer below 2000 feet above ground remain near or above freezing.

In addition to the now forecast higher temperatures near the surface, total water/snow-water equivalent has reduced in half from previous forecasts.

Precipitation moves in from the southwest between 5 and 6 PM. It ends around daybreak, somewhat later east in NJ.

With the warmer temps, here’s the model blend (NBM) precipitation type at 10 PM—

12z NBM Precipitation Type at 10 PM (Click on image for a larger view.)

The NBM mean and median snow accumulation have finally come closer together. I’m going with the median snowfall at this time—

12z NBM median total snowfall forecast ( Median = Half the models comprising this ensemble are showing more than these values, half are showing less.) (Click on image for a larger view.)

Where could this go wrong? Temperatures near the surface may be higher or lower than forecast. Unusual large snow pack on ground may reduce temperatures more than the models are accounting for.

That said, there should be no need for a snow-blower with this system. Updates later if things change.

Update

Updated Saturday 02/14/26 @ 11:01 PM — A quick update. Tonight’s models have more clouds. Precipitation moves in as early as 5-6 PM. I’m staying with the previous post’s snow totals.

Sunday Night Snow Forecast Update

Posted Saturday 02/14/26 @ 5:18 PM — An uncertain snow forecast remains uncertain. The models vary quite a bit regarding the total water equivalent precipitation. Values range from 0.30″ water (ECMWF) to 0.43″ (NAM-NEST) to the RRFS (0.13″).

Add to that the uncertainty continually changing temperatures during the precipitation event and we have a shifting landscape of snow accumulations depending upon location.

Additionally, snow falling is not going to mean snow accumulating in many areas, so snow depth accumulation is a moving target.

I’m again going to lean on the NBM for the forecast. Regarding precipitation type (rain/sleet/snow) here’s the NBM at midnight—

18z NBM Precipitation type forecast for midnight Sunday. There’s a large ± 2.3º position uncertainty in the 32º freezing line. (Click on image for a larger view.)

For now, I’m going with NBM mean snowfall accumulation—

19z NBM mean snowfall. (Click on image for a larger view.)
Sunday Night Snow Forecast Update

Posted Saturday 02/14/26 @ 9:50 AM — The ECMWF-AI has had 2 additional model runs (00z and 06z) since my last posting. During that time, it has flipped back and forth with higher and lower snow accumulations. I’m going to turn over the heavy lifting of this forecast to the NBM (which currently doesn’t include the AI models in its ensemble.)

Recent storms have ranged between the mean and the 75 percentile snow forecasts. Here are the latest NBM forecasts:

This morning’s 12z NBM forecast MEAN snow accumulation by Monday morning 7 AM (Click on image for a larger view.)

Here is the 75 Percentile (meaning that 75% of the models comprising the model blend are this amount or lower.)

While I’m trending towards somewhere between the mean and the 75 percentile based on past recent storms, this storm’s forecast evolution has been nothing like past storms.

Uncertainty remains high. The best illustration of this high uncertainty is the significant difference between the mean (above) and the median (shown below) snow accumulation forecasts, indicating a skewed distribution of model forecasts. Here’s the median —

This morning’s 12z NBM forecast MEDIAN snow accumulation by Monday morning 7 AM (Click on image for a larger view.)

I’ll update late this afternoon.

Weekend Forecast Update

Posted Friday 02/13/26 @ 7:45 PM — I’ve looked over the afternoon models (18z runs) that have become available. The 18z ECMWF-AI model shows the following accumulations, despite near ground temperatures being above freezing—

18z ECMWF-AI snow accumulation by 1 PM Monday. The model is on the upper range of the snowfall forecast, but with the latest GFS moving in this direction, it’s the model forecast I’m inclined to go with. (Click on image for a larger view.)

The GFS and ECMWF along with the latest German ICON model have also moved in this direction and have similar accumulations in the 2″ range for the city.

This snow forecast is especially challenging for the reasons below—

  • Above or near freezing near ground temperatures will allow some melting, especially at the onset. The above ECMWF-AI seems to account for this, as an all dry snow would have higher snow totals.
  • There is still some question of how far north storm and the precipitation shield will be which affects the total moisture falling as wet snow.
  • The models are assuming some snow accumulation on the back side of the storm into Monday morning. This can be tricky.
  • The higher resolution models- RRFS, NAM-NEST, NAM and Canadian RGEM were still showing little northward movement and little if any snowfall.

Saturday Forecast

Sunny and with seasonably near average temperatures. Somewhat breezy in the mid-day hours.

NBM high temperatures: Blue Bell, PA 43º Philadelphia, PA 45º
Average Uncertainty (based on standard deviation): ± 1.5º

Sunday Forecast

Sunshine through increasing high clouds in the morning. Increasingly cloudy through the afternoon. Snow begins about 8-10 PM and ends during the morning Monday. Details to follow

NBM high temperatures: Blue Bell, PA 40º Philadelphia, PA 42º
Low Uncertainty (based on standard deviation): ± 1.3º

A Very ‘Interesting’ Forecast- Snow Possible Again

Originally Posted Fri 6:10 PM — I was all set to post a simple weekend forecast this afternoon, with an emphasis on warming temperatures. The models appeared to have settled on a southern track storm and mild near surface temperatures that would obviate any concern about snowfall.

Here’s the ECMWF-AI temperature forecast for the next several days which is in range of the model blend—

Somehow, I hit the snow parameter on my grib2 viewer and I saw a return to the crazy 4+ inches of snow in our area by Monday morning?!

Let me cut to the chase— the ECMWF-AI model has returned to the large snowfall forecast of yesterday with a more northward track of the storm—

12z ECMWF-AI forecast for 1 AM Monday shows a northern-tracking storm, large precipitation shield and vertical profile temperatures (all three “critical thickness lines” to our south) that supports snow! This despite having the surface temperatures above freezing. (Click on image for a larger view.)

The regular 12z ECMWF shows a somewhat similar track with conditions supporting 2.5 inches of snow, more in southern Chester and Delaware counties.

The latest GFS is in-line with the ECMWF. About 2.5+ inches of snow.

Clearly, things are not yet settled with the track of the storm late Sunday. But the models are hovering around a 2.5″-4” snowfall by Monday morning.

I’ll be updating a complete forecast this evening.