1/10: A Few Systems to Watch This Week; the first Sunday PM-Monday

Saturday, January 10th 8pm

With our arctic blast finally retreating a bit...we have a few systems to watch this week.  Nothing big...but wintry potential none-the-less.

1) Sunday night-Monday AM: 

An area of high pressure over the east will slowly drift into the Atlantic Sunday.  At the same time...a disturbance will swing across the Gulf into the Mississippi Valley.  Southerly flow between the two will stream moisture into our area over colder, subfreezing air locked in at the surface,  This will lead to a wintry onset before warm air wins out and changes everyone over to rain during the day Monday.  

• Timing: Precipitation will break out southwest to northeast after midnight Sunday.  Although the high won't be locked in to our north like we usually see during wintry events, dry air in place will lead to evaporational cooling, likely enough for freezing rain at onset.  The best chance for this will be through sunrise...gradually changing to all rain mid morning.  The northern Valley and higher elevations may hang on to subfreezing temperatures a bit longer.
• Amounts: Currently thinking generally glaze to 0.10" of ice across the Shenandoah Valley before the changeover to rain...mainly on elevated surfaces.    As always, isolated higher amounts possible in the northern Valley.  This should be enough to have winter weather or freezing rain advisories issued sometime tomorrow.  Most roadways should be fine...but there could certainly be a few slick spots especially on bridges and overpasses.  I'll have an ice accumulation forecast map out sometime Sunday.

18z NAM for 1am Monday

2)Tuesday night-Wednesday:

After the first system moves out...a new high pressure center will drift across the Great Lakes and work into New England.  Models are hinting at a second disturbance forming off the Carolina Coast which could throw a bit more precipitation north towards our area.  Cold air will be a bit more established for this event...but how much precipitation/how far north precipitation gets is still to be decided.  Places south of I64 (from western North Carolina to the New River Valley to Richmond  to Danville) look to have a better shot here for some wintry precipitation.  We probably won't have a good handle on this second system until we get this first out of the way.  Just something to keep on the back burner for now.