Sunday 12/28: Update on Monday Night-Tuesday System

Sunday, December 7:30pm 
Update on Monday Night/Tuesday Snow

Here's a look at a few higher resolution models for snowfall Monday night through Tuesday which  I think are doing a pretty decent job showing snow accumulation potential.  The Canadian and European are also pretty close to this finally giving us some model agreement.

A few notes:

• Timing: Monday evening through Tuesday morning
• Thinking a dusting to an inch across the southern Valley (up to 2" at highest elevations)
• Expecting a sharp moisture cutoff to setup somewhere across the central or northern Valley..if you live in the Winchester area, you'll be lucky to see flakes...if you live in the Harrisonburg area, you'll be right near the cutoff....Lexington to Staunton looks like the sweet spot
• As you can see in the snow maps below, this will be highly elevation dependent.

I'll have another update including my first call snow map in the morning.

18z High Resolution 4-km NAM via WxBell

18z Parallel-GFS via WxBell

end update
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Sunday, December 28th 9:30 AM

Shenandoah Valley Forecast
Today: Cloudy with showers moving in during the afternoon.  Highs 53-57.

Tonight: Scattered showers.  Lows 38-42.

Monday: Showers in the AM...especially across southern portions of the Valley.  Otherwise mostly cloudy.  Highs 41-45

Monday Night: A few flurries or light snow showers developing overnight...best shot once again across southern Valley areas.  Lows 31-34.

Tuesday: Scattered light snow showers...tapering off in the afternoon. Highs 39-43.

Wednesday: Mostly sunny.  Highs 37-41.

Discussion:
Today will be our last warm day before chilly, more seasonable air works in for the coming work week. We have a cold front approaching from the Ohio Valley which will push through later today. A first wave of low pressure will ride along this frontal boundary producing on and off showers this afternoon into the day tomorrow.

8:30 am Radar

There is then a second wave which will ride along it bringing the potential for a period of snow showers Monday night into early Tuesday.  We are starting to see a bit more agreement between the models regarding both track and strength of this second system.  The Canadian backed off the most amped, northern solution mentioned in the blog yesterday...now coming a bit more in line with the GFS which is just a bit wetter than the driest model, the European.  The only real outlier left is the NAM which brings the developing low closest to the Carolina coast leading to moderate snow most of the day Tuesday...which is likely overdone.  The GFS most closely represents how I see this playing out with the best chance for light accumulations across the higher elevations of the southern Valley towards I64 (Highland, Augusta, Bath, and Rockbridge counties)...decreasing the further north you go as moisture becomes more scarce.  When the pattern isn't supportive for flakes, you take 'em however you can get 'em...more on this later.

6z gfs for Tuesday 7am