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—

Show More

WINTER WEATHER FORECAST

Update Sat @ 11:47 AM — The snow should be ending in the immediate PHL area by 1 PM, later east in NJ.

Here are estimated snow totals based on MRMS data (11:1 snow water ratio) as of 11 AM—

MRMS derived estimated snow totals 11:1 snow:water ratio as of 11 AM (Click on image for a larger view.)

Show More

Update Fri @ 11:02 AM — The latest GFS just became available. As is almost always the case, its totals are somewhat less than the NAM—

GFS 12z snow totals White contours are 1 inch increments. (Click on image for a larger view.)

I’m providing this morning’s NAM forecast again for easy comparison—

NAM 12z (Click on image for a larger view.)

My rule of thumb is to average the GFS and NAM for a best forecast.

Show More

Things seem to be coming together, based on the latest Water Vapor image and superimposed NAM/GFS potential vorticity (see explanation below)—

  • Last night's (Thurs) Water Vapor with Potential Vorticity

Update Thu @ 11:16 PM — Quick update. Latest GFS has increased snow totals almost as much as NAM.

Show More

Previously Posted Thu 5:32 PM —

The storm late Friday through Saturday time frame has entered into the range of the high resolution models.

Show More

With the high resolution models coming into the mix, here’s the forecast:

Friday:

An upper air disturbance and cold front will move through. We’ll have light snow break out northwest of the city as early as late morning Friday. Light snow/flurries on and off, mostly north and west of the city. Accumulation a dusting to 1/2 inch. High 34º sd 1.7º NBM model Blue Bell.

Snow starts Friday evening.

Most of our snow with this storm will occur Friday night into early Saturday morning.

Saturday:

Cloudy, cold and WINDY. Snow tapering and ending in the morning but lingering at the NJ shore. High 23.2 sd 2.9º NBM model Blue Bell

Sunday:

Sunny and cold. Windy. High 26.7 sd 2.2º


Earlier Storm Coverage:

Show More