214 
fxus61 krnk 070540 
afdrnk 


Area forecast discussion 
National Weather Service Blacksburg Virginia 
140 am EDT sun Sep 7 2008 


Synopsis... 
high pressure arrives overnight on the heels of Hanna...remaining 
until early next week. A strong cold front pushes into the middle 
Atlantic Tuesday into Wednesday morning. Another area of high 
pressure will be anchored across New England by the end of next 
week. 


&& 


Near term /until 6 am this morning/... 
isolated showers on the western slopes associated with deep northwest 
flow and residual front have all but dissipated early this evening 
so can likely run without mention overnight. Otherwise low clouds 
remain slow to exit across the northwest under upslope flow and 
lingering relative humidity in the wake of Hanna. Latest NAM slowly erodes this 
moisture overnight as somewhat drier air advects in from the Ohio 
Valley late. With clearing should see enough decoupling after 
midnight given weak high pressure to allow fog to develop espcly east 
per earlier heavy rain and across the western valleys. Think 
ridges will keep enough mixing to alleviate fog formation so 
trimmed back on coverage there overnight. Low temperatures still appear a 
bit cool outside the valleys so making minor upward adjusts espcly 
out east where surface moisture remains the highest. 


&& 


Short term /6 am this morning through Monday night/... 
warm and dry days will follow in the wake of Hanna. Did take a few 
degrees off of maximum T from mav MOS where the most rain fell 
today...since the ground will still be wet. Despite some drier air 
moving east...low level moisture may be sufficient in northwest NC for 
afternoon pop up storms in northwest NC on Monday. If dewpoints remain as 
warm as guidance suggests...then probability of precipitation may be necessary in the 
extreme southeast portion of the County Warning Area too. Leaned on the warmer side of 
guidance for maximum T...cooler side for min T with high pressure and 
light winds. 


&& 


Long term /Tuesday through Saturday/... 
expecting cold front to pass Tuesday after/Tuesday night...and increase probability of precipitation 
espec in the west for this event. Although early...spc's sref 
indicates a greater than 50% probability for 20k cravenbrooks near 
Danville. This somewhat impressive this many days out...so perhaps 
a severe threat will exist this day with the front. Southeast West Virginia also 
enters the right entrance region of jet so perhaps strong thunderstorms 
there too. Nice cool down behind this front...and tend to favored 
the cooler more amplified solutions of the GFS/GFS ensembles. 
However...if the front stalls along the NC/Virginia border as the European model (ecmwf) 
suggests...then probability of precipitation may be needed there for a large portion of 
Wednesday. Some cooler day will follow again...before SW flow/warmup 
evolves again with another cold front prognosticated for the end of next 
week. 


&& 


Aviation /06z Sunday through Thursday/... 
saturated ground and clearing skies will bring MVFR-IFR fog to 
lyh/Dan overnight. In the west...low clouds banking up against the 
western ridges to have low flight restrictions at lwb and blf. Roa 
will remain in a favored spot with westerly downsloping winds 
keeping VFR conditions through the period. Winds at roa could 
decouple late...therefore will have tempo MVFR visibilities toward 
sunrise. Conditions will improve through the morning with all 
sites return to VFR. 


Mountain and River Valley IFR/MVFR fog will be possible again Sunday 
night. 


A cold front will bring a return of rain showers/thunderstorms and rain on Tuesday. 


&& 


Hydrology... 
earlier rainfall totals of between 3 and 6 inches across parts of 
the foothills/Piedmont have resulted in minor river flooding along 
the Dan River at South Boston. Water levels will also likely rise 
to slightly above flood stage at Randolph on the Roanoke River on 
Sunday. 


&& 


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


&& 


$$ 
Synopsis...km 
near term...jh/jj 
short term...km 
long term...km 
aviation...js/rcs 
hydrology...