Weather

803 
fxus62 kgsp 292336 
afdgsp 


Area forecast discussion 
National Weather Service Greenville-Spartanburg SC 
736 PM EDT Friday Aug 29 2008 


Synopsis... 
a weak cold front will gradually dissipate as it moves south across 
the forecast area this weekend. High pressure will build south from 
the middle Atlantic through next week. 


&& 


Near term /through Saturday/... 
a quick update to remove pop from the mountains dew points are very low 
there. Instability and even cumulus minimal as well. No other changes 
at this time. 


Will not rule out a stray shower over the higher terrain through the 
early part of the evening...otherwise it should be fairly quiet with 
weak high pressure drifting in from the west. Fewer clouds tonight 
with left over low level moisture should allow more fog to develop 
as compared to last night. For low temperatures...favor the warmer FWC/met 
guidance keeping it in the upper 60s east of the mountains owing to the 
high dewpoint. 


On Saturday...a weak front will drift toward the region from the northwest. 
Although the models show decent moisture convergence over the mountains 
in the afternoon...this bit of low level forcing will not have much 
support aloft. We could get a few showers and thunderstorms outside 
the mountains in the afternoon...although it is unlikely. The mountains will 
stand the best chance because of the approaching front...but it is 
not looking that great...so pop will be limited to 30 percent and 
that is generous. The middle level dry air aloft will make it 
interesting as surface Delta Theta-E is about what you would expect 
in a favorable environment for wind damage producing storms. Temperatures 
were nudged up a degree or so. 


&& 


Short term /Saturday night through Monday/... 
as of 155 PM EDT Friday...convection will linger into the early 
evening on Saturday...but shouldn/T linger too long after sunset due 
to waning instability and weak forcing/shear. For Sunday...although 
relatively strong high pressure will begin to ridge into the area 
Sunday...easterly Post-frontal winds will provide some onshore flow 
to maintain some low level moisture. Although coverage of convection 
should be more limited than what will be observed Saturday... 
isolated to widely scattered diurnal storms will remain possible. 


The models are a bit at odds for Monday as to the southern extent of 
the penetration of drier/slightly cooler air associated with the 
strong high pressure over the northeast. The NAM is much more 
aggressive in bringing considerably drier air into the County warning forecast area on 
Monday...while the GFS hangs up some low-level moisture across the 
southern zones Monday afternoon. Either way...there shouldn/T be much 
in the way of convection over the area...and probability of precipitation will be limited to 
slight chance across the southern tier. 


&& 


Long term /Monday night through Friday/... 
as of 215 PM Friday...no significant changes were made to the medium 
range forecast. The GFS and European model (ecmwf) are still in reasonable 
agreement...at least through Thursday...regarding the upper level 
pattern. The main feature for the eastern Continental U.S. Will be the large ac 
and associated ridge that basically sits and spins over the middle 
Atlantic Tuesday through Friday. The clockwise flow around the ac will 
allow the main tc track to remain well south of the forecast area. Todays 12z 
GFS finally shows at least some resemblance of Gustav and 
Hanna...though still much weaker than the European model (ecmwf). It still looks as 
though...at this point...any deep tropical moisture plume associated 
with these systems will remain south and west of the western 
Carolinas through Friday. The European model (ecmwf) does show some moisture beginning 
to make its way northward towards the southern half of the forecast area on 
Friday...but the center of Hanna is still located over the NE Gulf with 
a generally northwest track. Will keep the dry forecast going through Friday. 
Using a blend of the mosguide and HPC guidance yields temperatures near to 
slightly above norms. 


&& 


Aviation /00z Saturday through Wednesday/... 
isolated showers are near kclt...and cannot be ruled out at the 
airfield. Otherwise...only scattered VFR clouds expected this 
evening. MVFR fog likely overnight with good low level moisture... 
light winds and clearing skies. IFR fog and ceiling likely at kavl. VFR 
should return quickly Sat morning. However...low level moisture 
moving in on Ely flow will lead to scattered MVFR clouds. These should 
rise to VFR by afternoon...with winds becoming southeasterly. 


Outlook...early morning fog and maybe some patchy stratus is 
possible the next few days which would mean periodic conditions MVFR 
or worse mainly centered around daybreak...with slight to low chance 
of mainly diurnal convection Saturday afternoon through Monday. High 
pressure ridging over the area on Tuesday should produce VFR 
conditions. 


&& 


Gsp watches/warnings/advisories... 
Georgia...none. 
NC...none. 
SC...none. 


&& 


$$ 
Synopsis...bsh 
near term...PM/rwh 
short term...jdl 
long term...bsh 
aviation...rwh