THIS WEEK’S WEATHER

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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.


WEEKEND WEATHER FORECAST

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Rex Blocking Pattern for through Wednesday

Posted Saturday 03/16/24 @ 9:44 AM — An upper air stable pattern, called a Rex Block (named after the meteorologist Daniel Rex, who identified this pattern) will keep a colder flow over our area through Wednesday.

ECMWF upper air/jet stream forecast winds at 300 mb for early Sunday. Rex block consisting of a stable couplet- upper high pressure directly north of upper low pressure, both cut off from the main jet flow (white arrows)

Here’s the current satellite water vapor image showing the developing Rex Block —

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. (Click on image for a larger view.)

Originally Posted Fri 7:04 PM — A cold front with its dynamics and showers to our south will sink further to our south Friday night.

Another cold front is waiting in the wings for Sunday morning Here’s the current water vapor satellite 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. Cold front to our south and another in the Great Lakes area. (Click on image for a larger view.)

High pressure will build in for Saturday. With the NBM recently running too cold, I’ll give the HRDPS a chance in the temperature forecast.

Saturday

Mostly Sunny.

HRDPS high temperatures: Blue Bell, PA 63ºº Philadelphia, PA 65º

The second cold front moves through Sunday morning.

Sunday

Several periods of cloudiness in the morning with the second front, becoming partly sunny in the afternoon. Increasingly WINDY and gusty. Temperatures decreasing in the mid afternoon.

HRDPS high temperatures: Blue Bell, PA 60º Philadelphia, PA 62º

The current trend is for colder temperatures next week through Wednesday. A generally dry period with no storms expected.


Weather… and Other Things 'Up in the Air'