Category Archives: Philadelphia Weather Outlook

Philadelphia Weather Outlook

THIS WEEK’S WEATHER

#weather #paweather #wx #pawx #philadelphia #phillywx

Friday Update

Update Fri 5/12 1:01 PM — A quick mobile update. The latest NBM is insistent on showers in the PHL area on Saturday. Several models keep them to our south, only affecting southern Chester and Delaware counties. Update this evening.


Forecast Update

Update Thu 5/11 9:57 PM — Hazy sunshine through a high thin cirrus cloud layer on Friday. High 85°-87°.

NBM forecast high temps for Friday (Click on image for a larger view.)

There’s still uncertainty with the northern extent of the light rain on Saturday. Philadelphia remains on the northern edge of the rain shield. Typical rain totals range from zero to 0.3 inches, depending on the model. The Canadian models and the latest HRRR consistently keep us dry. Tonight’s Model Blend (NBM) has 0.2-0.3 inches.

I’m leaning towards the drier forecast at this time.

Tonight’s 00z HRRR shows light rain to our south, no rain for the immediate PHL area. (Click on image for a larger view.)
Thursday Forecast Update

Update Wed 5/10 10:47 PM — After today’s blue skies, Thursday will have sunshine through high cirrus clouds for much of the day, as moisture aloft moves over the upper ridge.

I’ve been keeping my eye on Saturday. The longer range global models have rain showers Saturday morning into early afternoon. The few higher resolution models whose forecasts extend that far (NAM, RGEM) keep the showers to our south, even further south than the RGEM graphic posted immediately below. I’m leaning towards the drier forecast for Saturday at this time, but with much above average uncertainty.

Wednesday Forecast

Update Wed 05/10 @ 8:22 AM — No change in the forecast for Wednesday (today) through much of Friday. Friday will have hazy sunshine through increasing high clouds (cirrus); mid-level clouds move in late afternoon Friday.

In keeping with our new pattern of dry weather, most of the showers on Saturday will be to our south, in Delaware and South Jersey. Areas from north of the city and northward may be just cloudy.

CMC-RGEM shows most of the rain to our south on Saturday (Click on image for a larger view.)

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Our weather this coming week will be controlled by an upper air ridge with a disturbance moving over the top of the ridge towards us on Tuesday—

Today’s 12z NAEFS forecast for Tuesday shows the upper ridge in the middle of the country with a disturbance moving across the ridge and giving us some showers/rain on Tuesday. (Click on image for a larger view.)

This Tuesday system doesn’t look like a big rain maker. In fact, after the major rains (3-5″) of 8 days ago, it appears that we may even be entering into a much drier pattern for awhile.

Following Tuesday’s showers, high pressure builds in and fairly nice and tranquil weather is expected into at least Saturday.

Philadelphia Weather Outlook

THIS WEEK’S WEATHER

#weather #paweather #wx #pawx #philadelphia #phillywx

Friday and Weekend Outlook
Fri 05:27 PM Forecast Review — Not as much shower activity as forecast. Heavier activity was further east—

Update Fri 05/05 @ 11:13 AM — Despite the sunshine this morning, an upper air disturbance will bring scattered showers later this afternoon—

Satellite Water Vapor shows upper air disturbance to move through later Friday afternoon. (Click on image for a larger view.)

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The big upcoming change will be the transition to an upper level ridge. Temperatures will move back towards the low 70s by the weekend—

NAEFS Max Temperature forecast for late Saturday. Also visible are the 250 mb (jet stream level) contours showing the ridge that will slowly move towards us. Temperatures near 70 on Saturday and above 70 on Sunday are expected.

Thursday will be similar to today, Wednesday, although there should be noticeably fewer scattered sprinkles and perhaps some more breaks of sun.

A similar forecast for Friday.

The weekend looks to be dry with more sun!

Philadelphia Weather Outlook

THIS WEEK’S WEATHER

#weather #paweather #wx #pawx #philadelphia #phillywx

Wednesday Update -Continued Blocked Pattern

Update Wed 05/03 @ 9:37 AM —The blocked pattern will slowly transform into another blocked pattern over the weekend. By the weekend, our part of the country will be under more of an upper ridge than the current upper low. Until that time we’ll continue with unsettled weather: clouds, some sun, scattered showers, and cool temperatures.

Today, Wednesday, we’ll likely have the most widespread shower activity, but both Thursday and Friday may have a few late afternoon showers in some areas.

Here’s what things look like by Sunday—

NAEFS forecast for Sunday at 2 PM. The red line, (540 thickness line) captures the general configuration of the jet stream. Notice the extreme extent into northern Canada indicative of a blocked pattern. The Northeastern US will now be under more of the upper ridge. The weather should become drier and milder. (Click on image for a larger view.)
Tuesday – Continued Unsettled Weather

Update Tue 05/02 @ 8:16 AM — The upper air low has moved to north of NY State and it is expected to precess and end up over our area Wednesday and Thursday.

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Previously Posted Mon 12:00 PM —

This Week’s Weather Overview

The blocked pattern will slowly loosen over the next several days. The upper low still over the Great Lakes will continue to rotate disturbances over our area, giving us periods of clouds and some showers intermixed with some sun.

Water Vapor Satellite image Monday morning shows the low pressure system still over the Great Lakes, rotating disturbances over our area. This may continue through Thursday. (Click on image for a larger view.)