Category Archives: Philadelphia Area Weather Forecasts

Philadelphia Area Weather Forecasts

WEEKEND WEATHER FORECAST

#weather #paweather #wx #pawx #philadelphia

Sun 4:44PM Forecast Review — Well, we had little cloudiness, despite the GFS, HRRR and RAP model forecasts of cloud cover of 100%.

The NBM graphic I used with mean cloud cover captured it well.

In the fall of 2021, these models were upgraded with new cloud parameterization physics packages that have often over-forecast cloud cover. Until this issue is addressed, it’s something to keep in mind.

Sunday Forecast Update

Update Sat 03/18 @ 9:50 PM —We had more sunshine and less high, thin cloudiness from the city and westward Saturday than forecast.

Sunday starts sunny. There’s still uncertainty with the cloud cover early afternoon. Today’s GFS, HRRR and RAP still maintain a period of considerable low cloudiness Sunday from about noon until about 4 PM. More cloudiness northwest of the city. The HREF has minimal clouds.

There’s little disagreement about the very cold and the windy conditions for Sunday.

The NBM shows the wide “spread” (uncertainty) in the cloudiness forecast—

Today’s NBM shows uncertainty (red-violet contours) in the forecast cloudiness extending into Philadelphia from the northwest in the early afternoon. The red-violet represent 30- 40% cloud cover uncertainty. The models are split on this. I guess we’ll see.

Previously Posted Fri 5:22 PM —

A cold front will move through this evening (Friday). Some showers expected tonight about 10PM- midnight, with most of the activity just south of the city.

A second cold front will move through Saturday night and lingering upper air disturbance may affect us Sunday morning with clouds.

There’s uncertainty regarding the amount of cloud cover this weekend.

Average high temperature is 53-54º for the coming week.

Saturday

Some cloudiness in the morning behind the departing cold front may last until noon. High pressure builds in for sunshine through high, thin cloudiness in the afternoon.

High temperature 50.1º sd 1.1º ( NBM model location- Blue Bell, PA)

Sunday

Today’s GFS shows some upper air disturbance with moisture lingering Sunday morning. So some cloudiness is expected Sunday mid day. The NBM is more optimistic about sunshine for the day except areas far northwest of the city. It will be cold and windy.

High temperature 39.6º sd 2.4º ( NBM model location- Blue Bell, PA)

Winds
Today’s 19z NBM wind meteogram for location Wings Field Blue Bell PA (Click on image for a larger view.)

Philadelphia Area Weather Forecasts

THIS WEEK’S WEATHER

#weather #paweather #wx #pawx #philadelphia

Friday Forecast Update

Update Fri 03/17 @ 9:45 AM — This morning’s NBM keeps measurable precipitation (< 0.01″) in the Philadelphia area to a minimum during the daytime today. This is in keeping with previous forecasts. High temp 62º-65º

The latest HRRR does have some showers moving in, but during the evening hours, 9-11 PM.

Here’s the NBM—

Latest 12z NBM forecast total measurable precipitation Friday and Friday night. (Click on image for a larger view.)

In contrast, the latest HRRR has showers moving through 9-11 PM tonight—

Today’s 12z HRRR forecast for 11 PM Friday night. (Click on image for a larger view.)
Friday Forecast Update

Update Thu 03/16 @ 5:09 PM — Yesterday’s forecast for Friday had the line of showers dissipating before reaching the immediate Philadelphia area.

Today’s model forecasts suggest the showers make it into Philadelphia with reduced intensity— light scattered showers mid afternoon and early evening.

Friday: Some clouds and sun before noon, then increasingly cloudy with occasional bright skies into mid afternoon. Light showers move in from the west. Since there’s a range of model forecasts, I’ll turn it over to the NBM to do the heavy lifting—

Today’s 19z NBM 1 hour accumulated rain forecast for 3 PM Friday. It should be noted that the showers will likely be more spotty than suggested by this graphic. (Click on image for a larger view.)
Thursday and Friday Forecast

Update Wed 03/15 @ 5:18 PM — We’ll have a bit of high cloudiness Thursday morning which will dissipate for sunshine the remainder of Thursday.

A warm front followed by a cold front expected to bring clouds Friday and mild temperatures. The latest models have little in the way of rain Friday and Friday night, as a cold front will have its energy move to our north while a secondary low develops and moves off to our south. Much of the rain misses us.

ECMWF shows much of the rain dissipating as it moves towards Philadelphia Friday and Friday night. Little in the way of rain here.

Previously Posted Tue 4:48 PM —

Wednesday Forecast

The snow showers and the winds did not disappoint today. I thought the models did pretty good with this storm.

The cyclonic flow around the deep low off the New England coast will still be with us, as will the tight pressure gradient as high pressure builds in.

As a result, the winds on Wednesday will still be formidable and gusty, but should begin to subside Wednesday night.

Here’s the wind meteogram for Wings Field, Blue Bell for the next three days—

Today’s 19z NBM model Wind meteogram for location Blue Bell – Wings Field. Some wind gusts still in the 30-40+ mph range on Wednesday (Click on image for a larger view.)

Wednesday— The models are predicting sunny skies after some very early morning cloudiness. Highs 47º-48º

Thursday– sunny and milder. High near 57º Some clouds move in late in the afternoon.

Friday— Cloudy mild. Increasing winds. High near 60º Rain moves in during the early to mid afternoon ahead of a cold front.

Philadelphia Area Weather Forecasts

WEEKEND WEATHER FORECAST

#weather #paweather #wx #pawx #philadelphia

Update Sat 3/11 8:54 PM — Sunday’s forecast below is unchanged. High temp 46.5° sd 1.4°

Update Sat 03/11 @ 10:08 AM — We had the wet snow here before 8AM. The balance of precip will be light rain. There’s a wide range of model opinion regarding clearing today.

After reviewing the models, it appears that a considerable amount of low cloudiness will remain, but there’s a chance of some short-lived breaks of sun in some areas this afternoon. Some additional showers possible.

The HRRR shows another band of light showers moving through about 3-5 PM or so—

This morning’s 12z HRRR shows clouds (black/grey) and showers at 4 PM today. (Click on image for a larger view.)

That area is visible on this morning’s hybrid radar—

This morning’s Hybrid Radar with RAP model Omega overlay. Light showers may rotate through about 3 PM (Click on image for a larger view.)

Update Fri 3/10 11:02 PM — Tonight’s models continue to show non-accumulating wet snow showers, from the just outside of the city and north and west, Saturday morning.

Previously Posted Fri 4:51 PM —

This weekend will mark the transition into a different weather pattern than we’ve seen in awhile. Two low pressure systems will move in and develop – one Friday into Saturday and another late Sunday into Monday. These systems will pull cold air down from Canada and the jet stream pattern will become cyclonic and somewhat amplified along the Eastern US.

This translates into below average temperatures, windy and quite unsettled conditions, starting today (Friday) and into much of next week.

Saturday

Low pressure that brought rain Friday night will blossom in the western Atlantic. Upper level low pressure will merge with this storm. Wrap around moisture from this surface low will bring continued cloudy conditions and showers/snow showers on Saturday morning. It will be windy and cold. Some widely scattered showers may linger into the afternoon.

Here’s the GFS for Saturday—

GFS model forecast for Saturday 1 PM. Wrap around moisture from low pressure in the Atlantic will bring rain and snow showers. (Click on image for a larger view.)

Despite temperatures well above freezing, snow showers are expected to develop in some areas. It would not surprise me if the snow shower coverage is greater than predicted below—

NAM-NEST forecast Precipitation Type for 11AM Saturday. Blue: snow showers (Click on image for a larger view.)

High temperature 45.7º sd 1.5º ( NBM model location Blue Bell, PA)

Sunday

Another low pressure system approaches during the day. Sunday starts sunny through increasing high cloudiness.

Thickening and lowering cloudiness in the afternoon.

Some precip moves in during Sunday evening, which most likely will be rain in most areas.

GFS forecast for Sunday at 7 PM. Low pressure moving in from the west and south. (Click on image for a larger view.)

High temperature 46.9º sd 1.5º ( NBM model location Blue Bell, PA)

Winds

NBM Wind Meteogram for Blue Bell, PA (Click on image for a larger view.)

For next week, very deep low pressure develops near Cape Cod. We’ll be affected by windy conditions and cold temperatures.

GFS for Tuesday shows deep upper and surface low pressure systems—

GFS forecast Tuesday. Windy cold and unsettled here. (Click on image for a larger view.)
ECMWF 300 mb wind forecast (with red 500-1000 540 thickness) for Tuesday night shows broad but deep upper air trough in the East with closed low over the Northeast. (Click on image for a larger view.)

Daylight Saving Time and Weather Forecasts

Sunday morning is the beginning of Daylight Saving Time.  I love the extra daylight at the end of the day, but for  “weather nerds”, Daylight Saving Time means the models come out an hour later.  For those of us on Eastern Time, the evening models become available inconveniently late for the next day’s forecasts!

I’ve written extensively about this in past years—

Little Known Facts about Daylight Saving Time and TV Weather Forecasts

Daylight Saving Time and Weather Models

“Check Back at 11” — TV Weather and Daylight Saving Time