503 
fxus61 krnk 210810 
afdrnk 


Area forecast discussion 
National Weather Service Blacksburg Virginia 
310 am EST Friday Nov 21 2008 


Synopsis... 
with the arrival of cold air...mountain snow showers will continue 
into this afternoon. Strong high pressure builds tonight into Sunday. 


&& 


Near term /through tonight/... 
expanded Winter Weather Advisory south across the northwest 
mountains of North Carolina this morning. Strong shortwave dropping 
southeast triggering synoptic scale lift and an area of light 
to moderate snow across far western Virginia and southeast WV. 
Area of snow shifting southeast this morning. 


Another area of light snow occurring over southeast portions of 
forecast area this morning. Increased probability of precipitation and added light accumulation. 
Behind first wave...cold advection mountain snow showers kick in 
with significant accumulations limited to mainly the higher ridges 
of the west. Main shortwave will move east this afternoon...will keep 
snow shws rolling in southeast WV a little longer. 


A deep trough will be responsible for 30kt wind gusts late this 
morning...and a fire weather Special Weather Statement issued for the Piedmont as 
downsloping combined with continential Arctic air means low relative humidity 
values. See below. Went below MOS for highs in the advisory 
counties today. Played low temperatures close to mav gud tonight. 


&& 


Short term /Saturday through Saturday night/... 
surface high pressure will build over the area during this portion 
of the forecast. Also...a northwest flow shortwave trough will pass 
across the region. The combination of these two features will result 
in a dry forecast...but still with temperatures below normal for 
this time of the year. There will be increasing high clouds on 
Saturday due to the shortwave...but these should clear the area by 
Saturday night. Cloud cover will begin to return to the region from 
west to east on Sunday night in advance of a cold front approaching 
the region. 


&& 


Long term /Sunday through Thursday/... 
on Monday...strong cold front will move across the region 
bringing the area a good chance for rain on Monday with upslope 
snow showers Monday night into Tuesday. Deep southwesterly 
flow...strong low level jet and good moisture advection will 
arrive ahead of the front Monday morning. Rain to start in extreme 
SW Virginia Monday morning then over spread the area by early afternoon. 
By Monday evening...frontal showers will be along the coast. 
Current timing and atmospheric state support onset precipitation 
as rain. If the system is a little faster and arrives in the area 
prior to sunrise...brief period of snow and/or sleet may start the 
event. Dry slot will over take the area late Monday afternoon 
through early Tuesday morning. By sunrise...upslope snow shower 
should be falling as the upper level low moves across the Ohio 
Valley. Continuing upslope snow shower and gusty winds is on order 
Tuesday and Tuesday night. There could be flurries flying 
Wednesday morning unless high pressure enters early and shuts 
everything down. 


Temperatures are expected to remain below normal next by 5f to 10f. 


&& 


Aviation /08z Friday through Tuesday/... 
through the overnight hours...upslope induced snow showers will 
continue to develop over the mountains of southeast WV and neighboring SW 
Virginia. Primarily MVFR ceilings/visibilities will accompany these with some spots 
seeing IFR conditions at times. The current synoptically induced 
light snow over southwest Virginia is producing IFR/MVFR 
visibilities...but ceilings for the most part are low end VFR. Across the 
Piedmont of Virginia and North Carolina...radar was showing some 
good returns of snow in this area...but given how dry conditions 
are at the surface...at most some sprinkles or flurries with VFR 
conditions are expected here. 


Conditions in the mountains will be slow to improve to VFR. By the 
early afternoon Friday is when this should be realized. Then by 
the early evening...most areas will see clear skies. 


Winds today will increase with gusts approaching 30 kts possible. 


Drier weather expected Saturday and Sunday. Another cold front 
arrives Monday with chance of rain and snow showers. 


&& 


Fire weather... 
minimum relative humidities in the foothills and Piedmont on Friday 
will be 25 to 30 percent with winds gusting 20 to 30 miles per hour. After 
coordination with usfs will be issuing a fire danger statement for 
Friday. 


&& 


Rnk watches/warnings/advisories... 
Virginia...Winter Weather Advisory until noon EST today for vaz009-010- 
012-015. 
Winter Weather Advisory until 6 PM EST this afternoon for 
vaz007. 
NC...Winter Weather Advisory until noon EST today for ncz001-018. 
WV...Winter Weather Advisory until 6 PM EST this afternoon for 
wvz042-043-045. 


&& 


$$ 
Synopsis...jh/kk 
near term...js/km 
short term...ds/jh 
long term...rcs 
aviation...kk/rcs 
fire weather...