Monthly Archives: January 2026

Philadelphia Area Weather Forecasts

WEEKEND WEATHER FORECAST

#Philadelphia #weather #PAwx #PhillyWx

Forecast Review

Sun 9:15 AM —Forecast Review — With the exception of the light showers lasting into the night and very early morning hours, the model forecasts did remarkably well in predicting the precipitation amounts and the banding locations. Here’s the latest MRMS totals:

Sunday’s Eagle’s Forecast & Thursday’s Possible Storm

Posted Sunday 01/11/26 @ 9:18 AM — Sunny skies with a few periods of cloudiness passing through. The RRFS has continued to forecast wind gusts in a lower range for much of the day, BUT there’s a secondary area of clouds and even a few light widely scattered sprinkles or snow flurries that moves through about 4-5 PM with a secondary cold front.

12z RRFS forecast precipitation at 4 PM (Click on image for a larger view.)

The latest RRFS does show wind gusts briefly peaking near 35-40 mph at 4-5 PM with this secondary cold front but they subside from that high level by the fourth quarter.

The global, ensemble and AI models continue to forecast a coastal low to form near us on Thursday. Temperatures are forecast to be slightly above freezing at the start, so wet snow will have trouble accumulating. Total accumulation water equivalent looks to be between 0.15 and .30 inches. Possibly 1-2 inches of snow possible at best. The trend has been for this storm to form at or north of our latitude, having us miss much of the precip.

One More Thing… Next Week

Posted Saturday 01/10/26 @ 11:51 AM — As mentioned over previous days, the forecast configuration of the jet stream for next Thursday through Saturday lends itself to coastal storm development and a snow storm for our area.

While there has been nothing showing on the models through yesterday, last night’s models and especially this morning’s ECMWF-AI and new AIGFS shows a coastal storm for Thursday. Thermal profiles appear to be marginal, meaning wet snow or sleet changing to snow.

It’s way to early to hang your hat on this possibility. But you heard it here first. (And isn’t that why you read this blog?)

Today’s AIGFS forecast for Thursday t 1 PM. (Click on image for a larger view.)


Weekend Forecast Update

Posted Saturday 01/10/26 @ 11:08 AM — Today’s forecast remains on track with these changes:

  • Heavy rain band is forecast to be somewhat closer to Philadelphia.
  • Rain ends between 9 PM to 11 PM near the city and westward.

Radar 11 AM with superimposed RAP model Omega (Click on image for a larger view.)

Total Rainfall—

Today’s 13z NBM (Model Blend) total rainfall for Saturday. (Click on image for a larger view.)

Regarding Sunday, and more specifically the Eagles game at 4:30 PM, the latest RRFS continues with wind gusts in the 26 mph range, not the 40+ mph range I heard on the radio.

Originally Posted Fri 5:41 PM —Low pressure near the Great Lakes will spawn a secondary low near our area Saturday afternoon resulting in heavy rain during the day, ending after midnight Sunday.

Today’s 12z AIGFS forecast forecast for Saturday evening. (6 hour prior rainfall) (Click on image for a larger view.)

Colder air moves in on Sunday although, not as frigid as past weeks.

Saturday Forecast

Cloudy early. Lowering and thickening clouds late morning with rain heavy at times. Increasingly windy but remaining below 20 mph.

NBM high temperatures: Blue Bell, PA 44º Philadelphia, PA 47º
Higher than Average Uncertainty (based on standard deviation): ± 2.2º

Today’s 18z NBM total rainfall forecast (Click on image for a larger view.)

Sunday Forecast

A mix of clouds and sun. Quite windy with gusts over 30 mph. There is the possibility of a quick burst of light snow or snow showers during the Eagles game late afternoon or evening. according to this morning’s RRFS, but the afternoon RRFS keeps this to our south.

NBM high temperatures: Blue Bell, PA 42º Philadelphia, PA 43º
Slightly above average uncertainty (based on standard deviation): ± 2.1º

Eagles Game Forecast- Sunday 4:25 PM

5 PM: Temp 39.4º ± 3.0º Winds 13 ± 3.5 mph Gusts 25± 8 mph
7 PM: Temp 36.1º ± 2.1º Winds 12 ± 3 mph Gusts 23± 6 mph

Looking Ahead

A sharp and highly amplified jet flow will develop towards the end of next week. This has the potential for creating a coastal snow storm. Nothing showing at this time.

Philadelphia Weather Outlook

THIS WEEK’S WEATHER

#Philadelphia #weather #PAwx #PhillyWx

Friday Update

Posted Friday 01/09/26 @ 10:06 AM — Just as there was a dramatic change in the with Saturday’s high temperature forecast, a comparison of this morning’s models with the real time RTMA data suggests that the models are having some issues modeling today’s rain moving in.

Current (10AM) radar and Clear Channel (14) satellite image. The radar echos are closer than forecast by several models. (Click on image for a larger view.)

The actual observations (the RTMA) suggests that high pressure is blocking advance of the rain, while the advanced location of the line of showers west of our area suggests something quite different. The only thing I can say— there’s uncertainty with the amount of rain and its onset this afternoon.

It should be noted that the latest ECMWF is forecasting more rainfall this afternoon than was being forecast yesterday. Still going with 3-5 PM onset This continues to be an interesting system. Stay tuned.

Models guiding this forecast: HRRR, RTMA RRFS ECMWF

One More Thing

Posted Thursday 01/08/26 @ 7:54 PM — For days now, I (and everyone else) has been talking about temperatures reaching and exceeding 60º on Saturday. The forecast has changed significantly over the past 18-24 hours and the NBM (which is my go-to model for temperatures) has been slow to capture the trend.

The latest models from this afternoon (18z) are forecasting highs only in the mid 40s for Saturday due to an easterly flow instead of a previously forecast warmer southerly flow. The actual high temperatures will occur before noon on Saturday, dropping during the afternoon.

18z RRFS temperatures at 2 PM Fine black lines are 1º increments (Click on image for a larger view.)

Models guiding this forecast: GFS, NBM, RRFS , REFS, ECMWF-AI,

Rain moves in Late Afternoon Friday

Posted Thursday 01/08/26 @ 5:38 PM — The models have trended towards minimal/no rain before 4 PM for Philadelphia and its immediate western suburbs on Friday, somewhat earlier far western sections. Much of the day will cloudy, but a few bright intervals during the day. The Model Blend (NBM) is showing very light rain after 4 PM with totals less than 0.04″ but greater in western sections. Here’s the REFS forecast accumulation—

12z REFS forecast accumulated rainfall by10PM (Click on image for a larger view.)

Considerable rain for Saturday for most of the day. Clearing and sunny skies for Sunday.

Thursday through Sunday Outlook

Posted Wednesday 01/07/26 @ 11:30 AM — The forecast for above average temperatures through Saturday has been well-advertised. Here’s the NBM high temperature meteogram for Philadelphia—

12z NBM forecast Temperatures/Dew Points for grid point Philadelphia Center City. (Click on image for a larger view.)

Also as forecast, rain will move in on Friday, either early afternoon or mid to late afternoon.

There are differences between the models regarding the speed and development of this Friday system: The European and Canadian models are faster with rain moving in on Friday afternoon and much faster to move it out on Sunday.

The comparison below of the AIGFS and the ECMW-AI forecasts at 1 PM Sunday show significant differences:

Comparison of the rain coverage forecast for the six hours preceding 1 PM Sunday. AIGFS (slower) ECMWF-AI (faster). The Canadian GDPS-AI is somewhere in the middle of the two above.

If the AIGFS (and Canadian GDPS-AI) is correct, the Eagles will have to contend with some rain on Sunday. If the ECMWF-AI is correct, it will be mostly dry during the game.

Tuesday Update

Posted Tuesday 01/06/26 @ 9:34 AM —A low pressure system passing to our north this evening will bring a warm front through today followed by a cold front tomorrow. Despite the clouds this morning, it looks like sunshine through high clouds this afternoon.

Wednesday looks to be mostly sunny and quite windy. High 51º-52º

Thursday highs will be in the same 50-52º range during the daytime, but temperatures warm up further later Thursday evening.

There’s a range of model forecasts for the rain expected Friday through Saturday. The GFS and the AIGFS is slower with the rain onset on Friday and slower for it to exit on Sunday. There’s also a question of weather the rain will be substantial or less than 1/2″ total.

Todays’s 06z GFS forecast for 3 PM Friday. Rain doesn’t move in to the city until mid to late afternoon. (Click on image for a larger view.)

Models guiding this forecast: REFS, NBM, GFS. AIGFS

Originally Posted Sun 8:37 PM —This week’s main ‘theme’ will be an increase in warmth, expected to begin in earnest on Wednesday.

18z NBM (model blend) meteogram for temperature/dew point for KLOM Blue Bell. High temperatures on a gradual but consistent climb to near 50º on Wednesday.(Click on image for a larger view.)

Several systems are expected to pass to our north with any precipitation also staying north, extending as far south as Berks county on Monday.

For the Philadelphia region and the Delaware Valley, considerable cloudiness is expected on Monday as the low passes to our north and warm moist air is brought in aloft. Highs remain in the 30s.

Another system passes to our north on Wednesday, that brings a weak cold front through. The chill down from this front will be short-lived.

A slowly moving cold front approaching from the west with waves of low pressure moving along it will pass to our northwest on Friday; most of the precipitation (rain) will pass to our northwest. Yet another wave of low pressure moves up the same path on Saturday.

18z ECMWF-AI forecast for Friday early afternoon. The area of rain moves to our northwest, just brushing our area. (Click on image for a larger view.)

While the general features of this weather outlook are consistent across models, it would not take much of change in intensity or track to greatly change our area’s forecast and weather. Stay tuned.

Philadelphia Area Weather Forecasts

WEEKEND WEATHER FORECAST

#Philadelphia #weather #PAwx #PhillyWx

Sunday Update & Pattern Change??

Posted Sunday 01/04/26 @ 9:30 AM — Today’s Eagles will have clear skies and temperatures near 36º at the game start and around 30º when they win. Winds will be in the 6-11 mph range.

The warm up this week continues to be forecast by all the models with temperatures reaching 60º+ on Saturday. (Friday’s rain will keep temperatures in the 40s according to the ECMWF-AI or low 50s according to the NBM, not as high as previously forecast.)

As described last week, I think this warm up qualifies more as a passing “weather change” than a “pattern change”. Why? The same cold pattern returns by next Sunday! The following forecasts from the new hybrid AI HGEF and the NAEFS demonstrate the point—

Today, Sunday, as captured by the HGEFS—

Today’s (Sunday) HGEFS forecast. Notice the position of the jet flow (blue lines) along with the trough and ridge. We’ve been in a persistent trough “pattern” for quite some time. (Click on image for a larger view.)

By next Friday, we transition temporarily into upper ridge rather than a trough—

HGEFS forecast for Friday. Notice we’re now in a warmer ridge. But not for long! (Click on image for a larger view.)

By late next Sunday, we’re back into the same trough “pattern” we’ve been in through much of this past Fall and through December—

NAEFS forecast for next next Sunday. We’re back where we started with an upper level trough over the eastern half of the US. (Click on image for a larger view.)

Calling our brief warm up a ‘pattern change’ is presumptuous. The term “pattern change” should be reserved for when a jet flow pattern truly becomes persistent.

Originally Posted Fri 5:51 PM —Cold weather continues through the weekend as high pressure from Canada will continue to build in. The cold high pressure system will block precipitation in the south from reaching us.

12z NAEFS forecast for late Saturday afternoon. (Click on image for a larger view.)

Saturday Forecast

While the system moving to our south will not bring us any snow or rain, moisture aloft will result considerable cloudiness to cloudy for much of the day. Winds lighter but still noticalble.

NBM high temperatures: Blue Bell, PA 31º Philadelphia, PA 33º
Low uncertainty (based on standard deviation): ±1.2º

Sunday Forecast

Mostly sunny in the morning. Partly cloudy in the afternoon. Somewhat windy and gusty again in the afternoon. Cloudy towards sunset.

NBM high temperatures: Blue Bell, PA 35º Philadelphia, PA 38º
Lower Than Average Uncertainty (based on standard deviation): ± 1.0º

Friday’s Forecast Review talked of a ‘pattern change’, but looking at the long range forecast out to 300 hours, the warm up we’ll be seeing next Wednesday through next Friday will be more of ‘weather change’ than a ‘pattern change’. While it may last a few days into next weekend, the longer range looks quite changeable with alternating periods of colder and milder. I like to reserve the phrase ‘pattern change’ as something that becomes persistent over weeks.