151 
fxus61 krnk 072337 
afdrnk 


Area forecast discussion 
National Weather Service Blacksburg Virginia 
637 PM EST Sat Nov 7 2009 


Synopsis... 
high pressure will remain across the region until Monday. A cold 
front will cross through the area from the west on Tuesday. 


&& 


Near term /through Sunday/... 
high pressure remains over the region. Expect winds to decouple 
quickly this evening with nearly calm winds in the valleys. Models 
were showing a 30-40 knot jet across the northern County Warning 
Area. This will be enough the keep mixing going on the ridges. 
Similar to last night the highest elevations will be 10 to 15 
degrees warmer than the sheltered valleys for overnight lows. 


On Sunday forecast area is under the upper ridge with 850 mb 
temperatures in the +11 to +13 range. With a dry airmass and 
little to no cloud cover highs temperatures will be about 10 to 15 
degrees above normal. 


&& 


Short term /Sunday night through Tuesday/... 
high clouds will spread over the forecast area on Monday as the 
high moves offshore. Models were showing little increase in 
moisture below 700 mb until after 12z on Tuesday. So kept only a 
low chance of shower in before 18z Tuesday. Little change in 
guidance with the timing of the front. Still should be crossing 
the County Warning Area on Tuesday. 


&& 


Long term /Tuesday night through Saturday/... 
followed hpcguide for medium range which was a blend of European model (ecmwf) and 
gefs. Cold front and associated showers will push east across our 
region and should exit around 12z Wednesday. The front should shunt 
all deep moisture to the southeast Wednesday and Wednesday night including 
whats left of Ida as strong high pressure builds in from the northwest on 
Thursday. This should result in dry weather with large diurnal 
swings in temperatures again espcly by Thursday/Thursday night with the ridge 
about overhead. Next fast moving northern stream short wave trough will begin 
to approach from the northwest by Friday with return flow developing around 
the departing ridge offshore. This may bring a few pre-frontal rain showers 
to the SW during Friday but given such high heights will opt to 
leave out any mention. With return flow becoming deeper will allow 
for light probability of precipitation on Saturday. 


&& 


Aviation /00z Sunday through Thursday/... 
VFR conditions will prevail through Monday as high pressure both 
surface and aloft lingers across the area. A low level jet tonight 
will lead to some low level wind shear issues at roa/blf/lwb as an 
inversion sets up at the surface. This low level jet will exit before 
12z Sunday. 


High clouds will spread across the region on Monday as the high 
pressure system moves offshore. Ceilings will lower Monday night 
and Tuesday. A cold front coming through the area on Tuesday will 
bring the next chance for rain and MVFR conditions. 


&& 


Fire weather... 
dry weather can be expected again Sunday afternoon with minimum 
humidities of 25 to 30 percent for much of the area. Moisture will 
start to increase on Monday as high pressure moves offshore. 


&& 


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


&& 


$$ 
Synopsis...air mass 
near term...air mass 
short term...air mass 
long term...kk 
aviation...reb/wp 
fire weather...