805 
fxus61 krnk 191739 
afdrnk 


Area forecast discussion 
National Weather Service Blacksburg Virginia 
139 PM EDT Friday Mar 19 2010 


Synopsis... 
high pressure shifts east across the Gulf Coast states off the 
southeast coast through Saturday morning. A storm system 
will track from the middle of the country Saturday across our 
region by Monday. 


&& 


Near term /through tonight/... 
main change to the update was to lower the dewpoints for this 
afternoon. The 12z rnk sounding was much drier than the BUFKIT 
soundings. With a west northwest flow...downsloping winds will 
continue to dry out the valleys with dewpoints falling into the 
upper teens. Very light winds are expected across the area along 
with clear skies which will raise temperatures into the lower 60s 
in the west to lower 70s in the east. 


Previous discussion... 
mainly a temperature forecast this period. Low level wind flow will still 
out of the west-northwest today...and this will help to drive temperatures up under 
a sunny sky. Looking at highs about a degree or two warmer than 
Thursday...along and east of the Blue Ridge. 800 mb temperatures actually 
drop a degree or two in the west with a weak surface trough passing 
across...with no moisture. Tonight...high pressure extends north 
into the area with winds becoming light to calm once again. 
Dewpoints will start to edge up. Looking at lows again ranging 
from the lower 30s in the mountain valleys...to the 40s across the 
higher elevations and the Roanoke area. 


&& 


Short term /Saturday through Monday/... 
high pressure will remain in control for Saturday with a warm 
afternoon. Played highs Saturday closer to the warm adjmet values 
with readings from the middle 60s to the middle 70s. As the surface high 
slides east...clouds will increase Saturday night...ahead of a 
strong upper level low to the west. Warmed lows a few degrees in the 
southeast Saturday night. Warm air advection out ahead of the low 
and its accompanied isentropic lift could create a few showers 
Sunday...however...the greatest coverage will be further north 
closer to the warm front. With S-southeast 850 mb jet around 40-45knots...the 
higher elevations of northwest North Carolina and far southwestern 
Virginia could see gusty winds Sunday evening into Sunday night. 
Went with slower timing of the upper low...with the best chance of 
showers delayed until late Sunday night into Monday morning. 
Good dynamics...strong moisture transport...and strong isentropic 
lift support the idea of a band of heavy showers with chance for 
some low topped convection Sunday night into Monday. Nudged low 
temperatures up in the southeast to blend better with rah. Monday 
highs are a challenge as low tracks across NC...went with highs 
from the upper 40s in the northwest to lower 60s in the southeast. 


&& 


Long term /Monday night through Friday/... 
the cold air behind this upper level low is not as strong as 
originally forecast...due to the fact that the low cuts off from 
the northern stream and the cold air. However it could still be 
cold enough for some upslope snow showers in the western mountains 
Monday night into early Tuesday. An 850mb jet of 45 kts and decent 
pressure rises behind the low should bring a period of possible 
Wind Advisory criteria Tuesday morning along and west of the Blue 
Ridge. By later Tuesday warm air already begins to return into the 
area...cutting off any upslope snow/rain showers. 850mb 
temperatures surges into the 6-10c range Wednesday into Thursday 
as ridging develops overhead...this will allow high temperatures 
to surge above normal once again. Models begin to diverge by 
Thursday...but leaning towards the slower European model (ecmwf) solution. This 
brings another upper level low...and very similar weather as 
expected Sunday night into the area on Friday. 


&& 


Aviation /18z Friday through Wednesday/... 
VFR conditions through the taf period as dry airmass in place 
under high pressure. Possible middle-level moisture will be pushing 
into the area late Saturday afternoon from a southwesterly flow. 


A storm system will approach the region on Sunday into Monday 
with MVFR conditions likely in any precipitation that accompanies 
the front. 


&& 


Rnk watches/warnings/advisories... 
Virginia...none. 
NC...none. 
WV...none. 


&& 


$$ 
Synopsis...PM/wp 
near term...reb/wp 
short term...kk 
long term...PM 
aviation...reb/wp