637 
fxus61 krlx 211856 
afdrlx 


Area forecast discussion 
National Weather Service Charleston WV 
256 PM EDT Thursday Aug 21 2008 


Synopsis... 
high pressure will dominate through the first half of the weekend. A 
cold front will drape over the region late Sunday into Monday. 
Remnants of Fay may impact the area by the middle of next week. 


&& 


Near term /through Friday/... 
12z nam12 and local models bring area of weak 850 mb conv/moisture/Theta 
east maximum over southern mountains...southern coalfields...NE Kentucky this 
afternoon and evening. This feature appears to be a result of 
easterly flow off Atlantic...getting drawn NE around peripheral of 
ridge. 12z rnk sounding shows this nicely...with pooling of lowlevel 
moist against eastern slopes...resulting in low clouds across rnk 
vicinity. Aside from cumulus...not expecting much from this feature as it 
crosses southern portions of County Warning Area...with 500 mb ridge and dry air in 
place above lowlevel moist plume. Considering a few -shra developed 
over ridges yesterday...maintained schc probability of precipitation across ridges/elev heat 
src. Middle level cap and upper ridge will keep activity to a min and 
shallow...with any isolated -shra confined to southern mountains 


Models show an area of drying in lowlevels and lower dewpoints moving 
west from Virginia overnight...arriving across the mountains by 12z. This 
appears to be result of upper ridge building and rotating lowlevel 
drier air from northeast coast. This seems plausible considering 
lack of clouds on latest visible over eastern Virginia with lower dewpoints. With 
drying in all levels of atmos...dont expect any rain showers...or for that 
matter clouds...for Friday...even along the ridgetops. 


Went with a blend of mav/lmos/met for mint. For maxt on 
Friday...guidance...with exception of mav...again seem a couple degrees 
too cool. Generally kept ongoing forecast highs...which accounted for 
recent cool bias on guidance. 


&& 


Short term /Friday night through Sunday night/... 
a transition from our stagnant hot and dry pattern will finally 
begin towards the end of the weekend. Upper high gradually breaks 
down a bit Saturday through Saturday night...as an upper trough 
swings through the upper Midwest. The upper trough progresses into 
Ontario/Great Lakes region Sunday...while the southern end of 
associated cold front then slowly drapes down into the County Warning Area Sunday 
night. Based on latest models...I slowed down onset of chance probability of precipitation 
with this front by 6-12 hours...putting more of focus into Sunday 
night. 


Given strength of the upper high to this point...I would not be 
surprised to see even further delay of frontal approach in future 
model runs...and given this uncertainty I limited probability of precipitation to low chance 
range Sunday night. Because the front takes all weekend to get 
here...daytime temperatures will continue to be above normal through 
Sunday. 


&& 


Long term /Monday through Thursday/... 
followed HPC thinking for this portion of the forecast. Cold front 
is forecast to become stationary through Wednesday. Per TPC/HPC 
guidance...the remnants of Fay will be located near the Florida 
Panhandle/southern Alabama Sunday morning. This feature will then drift 
slowly north across Alabama. 


However...latest GFS indicates Fay may merge with the cold front and 
then move northeast across the area on Tuesday night into Wednesday. 


Either scenario should result in chances of showers and storms 
continuing through the remainder of the period. 


Because of the uncertainties...have opted not to be diurnal in 
nature with the showers and storms. 


Generally followed HPC temperature guidance. 


&& 


Aviation /19z Thursday through Tuesday/... 
an upper level impulse drifting northwestward from North Carolina 
may bring a shower/thunderstorm across the southern mountains this 
afternoon. Chances are minimal...therefore left out of bkw taf. 
Otherwise...afternoon scattered cumulus 4-5kft will give way to sky clear 
overnight. River and valley fog developing again between 06z and 
12z Friday morning...with IFR fog for heights...pkb...ckb. LIFR fog at 
at times crw and ekn. 


Aviation outlook /beyond 18z Friday/...no significant weather 
expected. 


&& 


Rlx watches/warnings/advisories... 
WV...none. 
Ohio...none. 
Kentucky...none. 
Virginia...none. 


&& 


$$ 
Synopsis...kmc/30 
near term...30 
short term...kmc 
long term...kmc 
aviation...30