Forecast for 1/21/11 Snowstorm
Update 8AM:
Philadelphia and its Immediate North and west suburbs have started to mix with sleet. Next few hours should feature heaviest precipitation. All precipitation moves out by 12-1PM. Storm is moving faster than expected.
540 Thickness has moved above Trenton, reflecting this change to sleet/freezing rain. Surface temperatures should remain below freezing making travel slick.
Above radar images shows concerns about collapsing band over central PA.
Update 4AM: All signs are looking great for good snow in the area- maybe even more than NY?
Impressive snow output from 6Z NAM: Best run yet...almost in 6 inch range in Philly. It picks up on the higher reflectivities also shown in short range models.
Expect at least 0.4 inches of QPF to come...as I remarked earlier, Philly area is in best region for most precipitation: 
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The snow is coming in fast- get ready for a full breakdown!!
First the basics:
1. Timing: Starting after 12AM, lasting until early afternoon (2-3PM end)
2. Snow Amounts:
Philly: 1-3 inches
Near Suburbs (Montco, Bucks, etc): 2-4 inches- Closer to city more towards 1.5-2 inch amounts, Doylestown more toward 3-4 inches
Far Suburbs (Lehigh Valley): 3-6+ inches
Map link- Click here For general depiction of areas of heaviest snowfall, icing concerns.
Discussion:
Precipitation is moving in as scheduled- should begin around 12AM-1AM.
Some observations:
1. The changeover will definitely happen in the city of Philadelphia- icing is a significant concern.
2. QPF is best around the Philadelphia metro, into central Jersey- though snow ratios will be higher around NYC, models point to less precipitation for them.
Here are sref images to illustrate #2:
Will continue to update throughout the night with latest data/obs.
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Updated: 1:10 PM GMT on January 21, 2012
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Overview: Snow Events 1/19-1/20 and 1/21
I will continue to update this post throughout the night- mainly focusing on the snow tonight and briefly commenting on the prospects for snow Saturday.
7:35PM:
The RUC Short Term Model continues to hint at some enhanced snowfall over the Philly region in the early morning hours:
The current radar returns are not bad considering we were only forecasted for flurries tonight.
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Updated: 12:40 AM GMT on January 20, 2012
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