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By Chris White

Weather Blog: Since Fredericksburg resides "in the seam" between the Richmond VA and Washington DC media markets this blog is a look at the weather from a Fredericksburg-centric point of view.

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Storm track slips southward

CLOSINGS / CANCELLATIONS: Click here for the latest list

Once again Fredericksburg stands on the cusp of a weather event that, pending the outcome,  could help restore or completely trash weather forecaster reputations that were already suffering from last weekend’s busted forecast.  As of last evening’s runs both the GFS and the NAM show the snow band slipping roughly 50 miles south of where it looked like during yesterday morning’s runs.  That would place the snow cutoff line just about over the ‘Burg, with more snow to the south and less – or none – to the north.  This outcome is supported by this morning’s short range Rapid Refresh model run.  Now here’s the latest official NWS Sterling snow accumulation map:

Based on what this amateur weather geek is seeing this map is over-optimistic for snow totals in the ‘Burg.  It’s entirely possible that a very heavy snow band can still materialize and dump several inches of snow in a couple of hours later this afternoon/evening, but I now believe the city of Fredericksburg will see 3-4 inches total accumulation rather than the 4-6 shown in the above graphic.  Thus the snow bands you see above should be shifted roughly 25 miles southward.

The culprit in all this has been an upper level system that is acting as an “accelerant” (like pouring gasoline on a fire) upon a weak surface low along the tail end of the old cold front still draped across the southeast U.S. This upper air map shows the system (pointed out via the white arrow):

The exact track of this system plus how much it strengthens the surface low is hard for the models – and thus the forecasters – to get a handle on.  That, plus a shift in track of 50 miles or so, is enough to create a lot of snow or a little for Fredericksburg.

In summary, yes I think the city will still see three inches of snow or so by the time everything winds down around midnight tonight.  But areas just to the north (even northern Stafford county) may not see much more than a dusting.

Permalink: http://news.fredericksburg.com/weather/2013/01/17/storm-track-slips-southward/