THIS WEEK’S WEATHER

Weekend Outlook

Update Thu @ 8:09 PM — Previous posts have indicated a warmup for the weekend as the jet flow becomes ridge-like over our area. The southwesterly flow will also bring moisture to our area in the form of clouds and some showers. There’s also the possibility of heavier rain next week.

GEFS (mode) jet stream wind forecast (250mb) for Monday morning showing ridge over northeast. The white area is referred to as a “jet streak”, an area of increased wind speed, this case approaching 198 mph. Rising and falling motions (rain) occur at certain areas of the jet streak. (Click on image for a larger view.)

For Saturday, a warm front is expected to move through our area with significant cloudiness for much of the day. No rain expected.

For Sunday, there has been recent uncertainty regarding the speed and placement of showers on Sunday far ahead of a frontal system.

The ECMWF has been forecasting a period of rain Sunday morning with partial clearing in the later afternoon. It’s forecasting about 0.20 inches of rain.

Today’s 12z ECMWF showing 3 hour rain accumulation at 1 PM Sunday. (Click on image for a larger view.)

The GFS has only a very light shower (< 0.02 inches) and mostly for areas north of the immediate Philadelphia area.

But today’s ICON and Canadian models have joined the ECMWF with the period of light rain in the morning. The NAM has also joined that group.

While ECMWF model is new to me (a limited but substantially increased data set only recently became available to the general public this past January 2022), I’m first learning its biases and tendencies and how to integrate its forecasts with the other main weather models like the GFS and NAM. As recently as last week though, a similar difference between the ECMWF and the GFS turned out in favor of the ECMWF forecast.

So with the ICON and Canadian RGEM leaning towards somewhat more rain, I’m leaning in that direction for Sunday. Most models have clouds thinning in the afternoon with temps in the 60s and WINDY conditions, although the latest GFS maintains a fair amount of cloudiness even in the afternoon.


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