#Philadelphia #weather #PAwx

Posted Thursday 03/06/25 @ 5:42 PM — The MRMS total rainfall graphic I posted in yesterday’s “Forecast Review” was posted before the storm had fully exited our area. Here’s the final rainfall totals for the region, which are impressive—

There isn’t much happening weather-wise over the next several days and into next week. We’ll be in a colder upper trough for some of the weekend. The next storm to affect our region may be next Thursday or Friday.

Wed 7:49 PM —Forecast Review —The majority of the rain has ended in the immediate PHL area. (There’s still heavy rain in NJ at this time.) Some additional showers are still possible this evening, Here is the MRMS rainfall summary for today’s rain.

The total rainfall was considerably greater than forecast by the models. The GFS was notably off.

It’s been a long time since we had such a heavy rain event.

Wednesday Forecast Update

Posted Wednesday 03/05/25 @ 4:16 PM — The HRRR, despite being a little slow with the first batch of rain, did well with the main line. Here’s what the radar looked like at 4:13 PM—

Posted Wednesday 03/05/25 @ 11:30 AM — Current radar shows the leading edge of rain much closer than the HRRR model has forecast. Even the 15z (10 AM EST) HRRR doesn’t show this.

I would expect the leading edge of the rain to be into Philadelphia within the next two hours. There is a line of heavier rain entering central PA. That might be the line of storms the HRRR is predicting for 5 PM.

Posted Wednesday 03/05/25 @ 8:25 AM — The models are consistently showing a strong line of storms with heavy rain and gusty winds to 50 mph coming through the city about 4 PM-

Addition showers possible during the evening hours. The actual cold front doesn’t come through until 2 AM Thursday morning.

Wednesday Forecast Update

Posted Tuesday 03/04/25 @ 8:49 PM — Tonight’s HRRR continues with a forecast of a line of storms moving through Philadelphia between 3 and 4 PM.

At 2 PM, the line is to our west, but with some break-out showers ahead of the main line—

Tuesday -Wednesday Forecast Update

Posted Tuesday 03/04/25 @ 9:14 AM — The models are forecasting these early morning clouds to dissipate by late morning. High temperatures 58º Blue Bell to 60º in the city.

The rain on Wednesday is now forecast to begin somewhat later in the morning as light showers. The heaviest rain now appears to move in about 3-6 PM with potential thunder and wind gusts approaching 50 mph.

Here’s the latest HRRR Precipitation Rate forecast—

Posted Monday 03/03/25 @ 4:57 PM —A low pressure system is developing in the Rockies and will move northeast bringing rain on Wednesday. Here’s the current water vapor image—

The latest models show a consistent forecast of rain moving in around 6-8 AM Wednesday. Before that time, warmer air ahead of the system will be with us on Tuesday with sunshine through high clouds. Highs on Tuesday 53º -56º (high uncertainty: ± 3º)

The rain on Wednesday is much-needed and the AI models are forecasting about 0.80 inches of rain, more far northwest and less into NJ. The deterministic ECMWF is similar, with localized 1″ amounts. The GFS model is only forecasting about 0.50 inches of rain, less into NJ. There may be pockets of heavier rain due to localized thunderstorms. Some high wind gusts possible beginning mid-afternoon Wednesday.

A cold front moves through about 1 AM Thursday morning. There may be lingering shower activity Thursday morning in eastern sections of NJ.

Originally Posted Sun 7:43 PM —Another cold day on Monday, followed by a warmup on Tuesday with temperatures rebounding into the low to mid 50s.

A storm is expected to move across the country and affect our weather on Wednesday with rain developing before daybreak.

We need some rain and unfortunately, the trend of the past few storms looks to continue, with the heaviest rain occurring to our far northwest.

Another trend has been for the predicted rainfall in our area to diminish with each subsequent model run. Yesterday, the total rainfall was predicted to be in the 0.8-1″ range around Philadelphia. The latest GFS posted above (in agreement with the ECMWF) has about half that amount forecast. (The latest ECMWF AI model still has about 0.8″ of rainfall here.)

I wish I could identify why this trend is occurring. It’s been going on since late last Spring.

Cooler weather returns for Thursday

#Philadelphia #weather #PAwx

Friday Forecast & Weekend Outlook

Posted Thursday 02/27/25 @ 5:30 PM — Today’s showers were just enough to keep the car washes busy. Total rainfall was as little as 0.03″ to 0.10″ just across the river in NJ.

Fast moving low pressure in western Canada will move eastward and will move north of our area on Saturday. This disturbance is just becoming visible on satellite water vapor imagery—

By 2 PM Friday, the GFS shows our area to be somewhat windy with partly sunny skies. Highs will have trouble just getting past 50º on Friday. The approaching low will be over the Great Lakes area—

A sharp cold front moves through Saturday and very cold temperatures move in for Sunday and Monday.

Posted Wednesday 02/26/25 @ 9:02 PM — After a mostly sunny day on Wednesday, we’ll see clouds move in for Thursday. Very light scattered showers will be with us by morning and continue into the afternoon.

As has been the case lately, we’ll see only 0.10″ of rain or less. The Philadelphia area has been in a “doughnut hole” of rain with most systems for the past 9 months or so. As mentioned in my forecast review, I don’t currently see a change in that pattern in the extended forecast range of 2 weeks.

For tomorrow, the new AI model from the ECMWF captures the pattern of the heavy rain bypassing our area—

Tue 9:31 PM —Forecast Review — We had much more sunshine than forecast today. The lack of showers was not a surprise, as the forecast for scattered amounts in the 0.01 to 0.02 range can often be model “noise”.

That said, I see a continuing lack of significant rainfall in our area. We went into the winter with a rainfall deficit and we have had only a few decent rainfalls over recent months. I don’t see much in the way of heavy rainfall in the extended model forecasts. A case in point— a week ago, the models suggested a decent rainfall for this Thursday. Current model forecasts are showing a minimal amount of rain on Thursday.

That trend towards lower rainfall amounts in the model forecasts has continued. The basic pattern has been for rain to move off to our northwest or out in the Atlantic. If this pattern continues, we’ll have some significant rainfall deficits by late Spring.

Here’s the latest total accumulated rainfall forecast for Thursday, based on the new AI model, the “ECMWF-AIFS-Single”—

Tuesday Forecast

Posted Monday 02/24/25 @ 6:17 PM — The weak front that moves through on Tuesday is expected to bring plenty of clouds and mild temperatures despite the lack of sunshine. Some sprinkles are possible anywhere from 3 PM to 7 PM, but any precip will be extremely light, on the order of 0.01 to 0.02 inches of water.

It should be noted that the ECMWF and the new ECMWF “Single AI” model show no precip at all in Philadelphia and very light precip to the far northwest, near Allentown and Reading. Depending upon the models, the clouds may dissipate late afternoon or hang tight a bit longer.

Previously Posted Sun @ 4:38 PM — —A trend towards milder weather this week has been well-advertised. As we saw about two weeks ago, the AI models are forecasting highs to be somewhat higher than the operational models.

First, here’s what’s happening now, Sunday afternoon—

Monday will be windy and gusty in the afternoon, ahead of a weak front.

The low pressure system in Canada (L) will move rapidly eastward and a front will develop to our west associated with that northern system on Tuesday with clouds and some showers possible mid afternoon according to the GFS and NAM-NEST.

It will briefly colder Tuesday night, but temperatures partly rebound on Wednesday.

Here’s the NBM temperature meteogram, for Blue Bell, showing its high temperatures (TMAX)—

The new ECMWF-Single AI model shows these highs—

By Thursday afternoon, another stronger cold front is expected to move through with some rain—

A cool down for Friday and another cold weekend follows, but then a big warmup for the first week in March.