Friday, January 2, 2015

Friday 1/2: Brief Wintry Mix Saturday AM

Friday, January 2nd 2014 2pm

Shenandoah Valley Forecast

Today: Increasing clouds.  Highs 44-48.

Tonight: Cloudy. Light sleet/rain/freezing rain showers developing towards daybreak. Lows 30-34.

Saturday: A light rain/sleet/freezing rain mix in the morning...on and off rain showers/drizzle continuing through the rest of the day.  Highs 37-41.

Sunday: Rain showers during the morning...tapering off during the afternoon.  Highs 50-54.

Monday: Sunny and cold.  Highs 34-38.  

An area of low pressure is developing along the Texas Gulf Coast which will be our weather maker this weekend.  This system will track northeast into the Ohio Valley...overspreading light precipitation into the area out ahead of it beginning early Saturday morning.  At the same time, an area of high pressure currently overhead will retreat north and east but remain close enough to keep a wedge of cold air in place for the onset of precipitation.  Southerly flow around the east side of the low will eventually win out and erode the wedge, warming things up as we head towards Sunday.  The trailing cold front will then swing through and bring us some of the coldest air we've seen so far this season for the better part of next week....right now looks like we could see highs in the 20s/lows in the 10s for a day or two.
Radar 1:11pm
Saturday Morning Wintry Mix:
Looks like this will be another one of those "limited moisture + marginal temperatures" type wintry events.  There will be patchy areas of sleet/freezing rain at onset...but I think most Valley areas quickly changeover to a cold plain rain.  
12z High Res NAM Simulated Radar 5am Saturday 
Below are Saturday 10am temperatures depicted by the 12z high resolution NAM.  You can see there's a bit of a wedge in place along the eastern side of the Appalachians....but most locations have now warmed above freezing.  The higher elevations will hang onto subfreezing temperatures a few hours longer so wintry mix will persist longer there.

12z High Res NAM Temperatures 10am Saturday
Bottom Line:
  • A brief period of wintry weather Saturday (4-10am)
  • Most Valley locations stay just wet...isolated colder spots and higher elevations could see light coating of sleet + trace amounts of ice
  • Cold wedge erodes for everyone by afternoon...changing everyone over to rain

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