Category Archives: Philadelphia Weather Outlook

Philadelphia Weather Outlook

THIS WEEK’S WEATHER

#Philadelphia #weather #PAwx

Quick Weekend Outlook

Update Fri 3/29 11:16 PM — Too many things happening today, including a router malfunction and home electrical breaker issue. So no Weekend Weather Forecast in its usual form. Just want to say that the showers on Saturday won’t arrive until after 6 PM, despite what I’m hearing on TV.

Weekend Outlook Early Edition

Posted Friday 03/29/24 @ 9:48 AM — Today, Friday will be sunny and quite windy.

The first of a series of fast moving clipper disturbances will move across the ridge ridge (see yesterday’s graphic) to bring some light showers late Saturday.

WV image Friday morning shows the first of several clippers that will bring light showers Saturday evening. Another clipper and a warm front will bring a chance of showers and rain Monday through Wednesday. (Click on image for a larger view.)

We should see increasing cloudiness between noon and 2 PM Saturday. Light showers possible after 5-6 PM. High near 60.

Easter Sunday will have sunshine through high cloudiness. No rain. High low 60s.

Friday through Sunday Outlook

Posted Thursday 03/28/24 @ 5:51 PM —

Thu 5:51 PM —Forecast Review — The models over-forecast the rainfall in Philadelphia today. A nose of dryer air kept rainfall to a minimum west of the Delaware river.

I guess the Phillies could have played today, but except for the wind, they’ll have a nicer day on Friday for their season opener.

Friday does look sunny, but very windy, especially in the afternoon. Highs 54º Blue Bell, 57º Philadelphia.

Saturday looks partly to mostly sunny, less wind. There may be a period of cloudiness early afternoon. Some clouds move in again towards evening with showers possible in the mid evening. Some models have these showers staying to our north.

A series of disturbances moving across a somewhat stationary upper air ridge will begin to affect our weather beginning Sunday. Here’s the NAEFS forecast for Sunday—

NAEFS model statistical “mode” version with overlayed GEFS model “bias-corrected” precipitation forecast for Sunday. Disturbances moving over the upper ridge may bring unsettled weather late Sunday through Wednesday (Click on image for a larger view.)

An approaching disturbance will bring a mix of clouds and sun on Sunday. The current forecast has showers moving to our south later Sunday, but this could change.

Thursday Update through Saturday

Posted Thursday 03/28/24 @ 11:01 AM — Current surface analysis shows a stalled front just through Philadelphia with waves of low pressure developing along the front—

Current Surface Analysis with Mean Sea Level pressure, surface winds and surface 3 hour pressure delta (HRRR) I’ve drawn the cold front’s approximate position. (Click on image for a larger view.)

It appears that the eastern track forecast for the heaviest rainfall from this system was the most accurate, and additional rainfall through this afternoon is expected with it being considerably heavier along the Jersey Shore and east of Philadelphia.

The rain tapers off between 4 and 6 PM from Philadelphia westward. Here’s the latest NAM-NEST at 5 PM Thursday—

03-28-24 12z NAM-NEST 1 hour accumulated rainfall at 6 PM (Click on image for a larger view.)

For Saturday, a clipper-type system will bring considerable clouds and showers late—about 6 PM according to some models and a bit earlier, late afternoon, according to some other models.

Thursday Forecast Update- Phillies Opener Rescheduled

Posted Wednesday 03/27/24 @ 5:18 PM — The rain came in slowly on Wednesday, but by 3 PM, most areas from Philadelphia westward were getting rain from this developing coastal system.

Phillies Opening Day has been rescheduled due to the wet forecast. The model trends over the past day have the heavy rain shield even further westward again, with rain likely all day Thursday and well into Thursday evening. The heavy rainfall totals forecast has increased. Here’s the latest NBM —

03-27-24 18z NBM total accumulated rainfall Wednesday into Thursday. (Click on image for a larger view.)
Wednesday Thursday Update

Posted Tuesday 03/26/24 @ 10:14 PM — It looks like light scattered showers slowly move move in from the west on Wednesday, as early as 11 AM but most likely between noon and 3 PM. Rain coverage increases but there may be a lull during the evening until about 3 AM Thursday morning.

Scattered rain through Thursday, much heavier near the Jersey Shore.

The models are converging on a more eastern track for the heavy rain axis. In the city and west, it will be less than 1″. Heavier rain east and at the shore.

Here’s the current GFS forecast rain accumulation through Thursday —

03-26-24 18z GFS rain accumulation through Thursday. Contours are 0.25 inch increments (Click on image for a larger view.)

It’s not looking great for the Phillies opening day.

Tuesday Update

Posted Tuesday 03/26/24 @ 8:04 AM — Last night’s models have less cloudiness from Philadelphia and westward this morning. Thickening clouds still expected during the afternoon.

For Thursday, there’s a range of model forecasts regarding the heavy rain banding. The majority of the models keep the heaviest rain east into NJ and even further eastward. The GFS maintains heavy rain into Philadelphia—

Here’s the latest ECMWF—

Last night’s ECMWF shows the heaviest rain in the Atlantic. (Click on image for a larger view.)

Here’s the latest GFS—

03-26-24 06z GFS accumulated rain forecast by Thursday 10 PM (Click on image for a larger view.)

For last Saturday’s rain, the GFS also had a consistently westward track and was correct, but it had support from other models. This time, the GFS is the most westward. Updates later.

Tuesday

Posted Monday 03/25/24 @ 7:49 PM — A stationary area of low pressure in the western Atlantic will rotate clouds into our area on Tuesday. An approaching cold front will be here on Wednesday.

GFS forecast for 5 AM Tuesday shows a stationary vertically stacked low in the Western Atlantic. Moisture around this low will rotate into our area from the east on Tuesday. A high pressure ridge over our area will block precip from the west and east. The precipitation from the cold front is visible in the western sections of Ohio. (Click on image for a larger view.)

Tuesday -An easterly wind and thickening clouds during the day. Highs 51-53º but high uncertainty with a high NBM standard deviation of ± 3.5º

Some showers move in from the west on Wednesday, but rainfall totals look light.

Incredibly, the models are trending towards another 1″ + rainfall on Thursday, especially for NJ.

Overview

Originally Posted Mon 3:08 PM —Following Monday’s delightfully sunny but cool weather, the week ahead will be cloudier with several systems expected to affect us.

Here’ the satellite current water vapor image—

WV image Monday afternoon. A cold front in the Midwest will have its energy shear off to our north as it passes through Wednesday into Thursday, bringing showers. Low pressure is expected to develop along this front and will bring some rain to our area Thursday, but the main system will be slightly to our east. (Click on image for a larger view.)

A cold front in the Midwest will have its energy shear off to our north as it passes through Wednesday into Thursday, bringing showers. Low pressure is expected to develop along this front and will bring some rain to our area Thursday, but the main system will be slightly to our east.

Here’s the current GEFS forecast for Thursday—

03-25-24 12z GEFS forecast for early Thursday morning. Low pressure will move slightly east of our are, but some rain is still expected here. (Update: latest models Monday show possibility of 1″ rainfall. )( Click on image for a larger view.)
Philadelphia Weather Outlook

THIS WEEK’S WEATHER

#Philadelphia #weather #PAwx

Friday and Saturday

Posted Thursday 03/21/24 @ 8:28 PM — Friday looks to be one of the better days this week. While temperatures will still be colder than seasonal average (56º average while Friday ~50º), winds will have reduced considerably and we’ll see sunshine in the morning and early afternoon. This afternoon’s models show an area of cloudiness moving in about 2-4 PM from the south, out ahead of the storm to affect our area Friday night into Saturday.

Saturday still looks cloudy with heavy rain. The exact axis of the rain now varies from model to model but many areas will see at least 1.5″ to up to 3″.

RRFS and ECMWF Open Data
For weather model aficionados, the ECMWF has made a higher resolution model available as part of the their free, open data initiative. Also, the development of the RRFS has hit a snag. While still expected for release in early 2025, there are issues. I’ve updated my RRFS page with more info.
Yet Another Heavy Rainstorm

Posted Thursday 03/21/24 @ 9:24 AM — The forecast for Saturday continues to trend towards higher rainfall levels. A storm, originally thought to move east into the Atlantic, just brushing us, now has a forecast track that has its heavy rainfall axis directly over the Delaware Valley on Saturday. The latest ECMWF continues that trend with rainfall here in the 3″ range.

03-21-24 06z ECMWF accumulated rainfall through 6 PM Saturday. (Click on image for a larger view.)

It’s also looking VERY WINDY Saturday night. Stay tuned.

Colder Thursday- Heavy Rain Saturday

Posted Wednesday 03/20/24 @ 8:39 PM — The cold front moved through and the high winds predicted for this evening have developed. The latest RTMA shows there are wind gusts in the 40+ mph in and around Philadelphia this evening.

Thursday should be sunny and still windy. It will be cold with highs of only 43º (Blue Bell) 45º (Philadelphia)

Friday sunny with highs 48º- 51º

A coastal storm will affect us late Friday night after midnight through Saturday. Heavy rain, especially east into NJ. Another 1-3″ rainfall for our area!

CMC-RGEM accumulated rain forecast and mean sea level pressure at 5 PM Saturday. Low pressure still at Jersey Coast. (Click on image for a larger view.)
Windy Somewhat Wet Wednesday

Posted Tuesday 03/19/24 @ 9:00 PM — I was thinking a few days ago that this week might be a bit boring here weather-wise, but another cold front behind a clipper disturbance will bring some very strong winds on Wednesday afternoon and evening.

Several models keep the light showers north of the city, but the trend this afternoon has been for showers to move through parts of the city as well.

NAM-NEST total rainfall through 8 PM Wednesday evening. Rainfall is generally 0.05″ to as much as 0.11″. (Click on image for a larger view.)

Winds gusts are expected to be high, especially late afternoon and evening. The NAM-NEST has gusts 35-40+ mph. (The Canadian HRDPS is in its own realm with gusts near 50 mph, but it shouldn’t be totally ignored. )

NAM-NEST wind gusts at 8 PM Wednesday. (Click on image for a larger view.)

Saturday is looking rainy from a coastal storm, originally expected to move to our east, but now appears to track westward and bringing another 1″ plus of rain to our area, greater amounts east in NJ.

Posted Monday 03/18/24 @ 6:15 PM — We had periods of clouds moving through today from “lake effect” precipitation that stayed in northwest Pennsylvania. The coldest core of this cold outbreak is poised to move in on Tuesday. Here’s the latest water vapor image—

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. Coldest air moving in from the west. The disturbance that will bring showers Wednesday is just becoming visible (red oval). (Click on image for a larger view.)

The models are in increasing agreement with a clipper disturbance bringing light showers on Wednesday, with the ‘heaviest’ precip north of our area. Total rainfall here looks quite light.

Some heavy rain looking more likely late Friday into Saturday.

Originally Posted Sun 8:15 PM —For the coming week, the blocked pattern remains with our area being in the colder part of the jet flow. Not much happening beyond that.

Over past months, it seemed like every potential storm was inundating us with heavy rain. Things seem to have changed, with recent disturbances passing to our south and north.

The same is expected this coming week with a northern clipper disturbance late Wednesday staying mostly to our north and a more potent system later in the week (Friday-Saturday) that appears to stay [mostly] to our south.

Here’s the current system for late Wednesday, according to the Canadian RGEM—

Canadian RGEM forecast for Wednesday evening 8 PM. A clipper-type system will move to our north, possibly grazing northern suburbs with light showers. (Click on image for a larger view.)

It’s been well-advertised that the coming week will be cooler/colder. Generally sunny skies expected but there may be periods later in the week where warm air tries to make it back here, resulting in some clouds.