Category Archives: Winter Storm Outlook

THIS WEEK’S WEATHER

MIXED SLEET/FREEZING RAIN THURSDAY NIGHT CHANGING TO ALL RAIN BY MORNING

Fri 10:05 AM Forecast Review — So, we had even more ice accumulation than I would have guessed and temperatures did fall at or below freezing well into NJ, as forecast by last night’s NAM-NEST and HRRR.  The URMA shows temperatures at 2 AM—
URMA from 2 AM Friday morning  (URMA= “UnRestricted Mesoscale Analysis”)  The URMA represents actual temperatures and conditions and is used for model verification.  Since it represents corrected observations, the URMA is is released with a six hour delay to allow for corrected data input. (Click on image for a larger view.)

While the changeover to rain occurred, there was continued ice accretion past the rise in air temperatures above 32º.   Most of the models over-predicted the rate of temperature rise.  The major global models (GFS, ECMWF) never showed the temperatures drops into NJ. 

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SNOW FOR SUNDAY POSSIBLE

Update Fri @ 9:52 AM — No significant change in the snow forecast. I’m going to borrow from my previous posts which basically captures the forecast:

From yesterday: “The models have all moved to a weak, unphased system with development occurring further from us. Totals of a coating to an inch are now forecast. “

From Tuesday: “A cold front moves through Saturday night and stalls. Low pressure develops in the southeast coastal area. Track appears offshore, but several models have some moisture over-running the stalled frontal boundary with some snow possible here on Sunday.”

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Originally Posted Wed 10:02 AM

  • GFS forecast with increasingly phased system Sunday

The difference for us between a phased system and unphased is a snowfall of >4 inches….. vs 1″, maybe 2″(unphased).

The German ICON and Canadian GEPS were somewhat closer to the unphased ECMWF. So this is “still up in the air”

Stay tuned. I’ll have a better sense of the trend late this afternoon after the other global models and ensembles have become available.

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HEAVY RAIN ENDS FRIDAY -NO SLEET OR SNOW EXPECTED

Update Fri @ 4:54 PM — I sure hope my forecast is correct. The temperature is dropping. The latest MRMS shows the back end of the precipitation near upper Montgomery County is changing to snow. Most areas still rain or what’s called “cold stratiform rain”

MRMS at 4:41 PM The MRMS shows actual precipitation type: rain vs snow. Snow is shown appropriately as white. *Click on image to animate .* (Click on image for a larger view.) Super-imposed are current observed temperatures.

Update Fri @ 3:34 PM

“All this rain, I hope it doesn’t turn to snow”

It won’t, at least around here. I’m sticking with the NBM and Canadian RGEM models which clearly show the precipitation departs before the cold air comes in—

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