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Posted at 03:40 PM ET, 01/23/2013

Friday’s fickle storm: Will snowflakes fall or fail?


Models simulate light snow over the D.C. area Friday afternoon and evening. But note a hole in the precipitation east of the mountains in the Canadian, GFS, and NAM simulations. That is a concern in forecasting amounts. (StormVistaWeatherModels.com)


Since early in the week, models have trended drier with the amount of snow forecast for the D.C. area Friday afternoon, with some showing none at all. But, overall, most models simulate a least a little snow for the region and “a little” is what we think is most likely.

Possible timing for snow: Friday afternoon and evening

Chance of at least one inch accumulation: 50 percent

Although amounts may be modest, the timing of the snow coinciding with the Friday evening rush hour makes this event worth paying attention to. Temperatures will be plenty cold for snow to stick - in the 20s.

Link: How to list your weather-related closings and delays

The problem for snow lovers hoping for substantial amounts is that the storm is coming from the west and doesn’t have much moisture to work with. As it crosses the mountains, models are pretty consistent in reducing the intensity of the snowfall.


NWS Hydrometeorological Prediction Center forecasts just a 30-40 percent chance of 1” of snow over D.C. and a snow hole
This snow shadow or “D.C. snow hole” effect is pretty common with storms coming from the west. That’s why our big snow storms come from the south and southeast instead - where they can tap Gulf of Mexico and/or Atlantic mositure.

In light of the possible “snow hole” eventuality, Wes Junker, Capital Weather Gang winter weather expert, gives the following most likely scenarios for this snow event :

The heaviest (3 to 6 inches) of the three scenarios mentioned yesterday now appears off the table.

Two possible scenarios remain for Friday’s storm:

Our favored 1-3 inch scenario from yesterday still is on the table though amounts may be more towards the 1-2 inch range than 3. (50 percent chance)

The other scenario is for D.C. to get caught firmly in a snow hole as the westerly flow and down-sloping on the east side of the mountains limits precipitation and we quickly dry slot resulting in snowfall amounts less than 1 inch (50 percent chance).

Tomorrow, we’ll update these thoughts and include a snowfall accumulation forecast map.

By  |  03:40 PM ET, 01/23/2013

Categories:  Latest, Winter Storms

 
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