307 
fxus62 kgsp 071617 
afdgsp 


Area forecast discussion 
National Weather Service Greenville-Spartanburg SC 
1117 am EST Wednesday Jan 7 2009 


Synopsis... 
a cold front will move east across the area today. High pressure 
will build over the region late Thursday and Friday...followed by 
another cold front this weekend. High pressure is then expected to 
rebuild over the area late Sunday and Monday. 


&& 


Near term /through tonight/... 
recent radar images and surface observations indicate that rainfall 
rates have decreased significantly over the past several hours. 
Shower coverage will continue to decrease through the day as the surface 
wave and associated front push away from the forecast area. I will 
time the decrease in probability of precipitation for the update and cancel the Flash Flood 
Watch. Recent surface observations indicate that winds across the County Warning Area 
continue to strengthen this morning. Recent MOS guidance and 
forecast soundings indicate that speeds will gradually increase 
through the afternoon...dissipating after sunset. It appears that 
the Wind Advisory is well placed and timed. 


Temperature will generally remain steady through the early afternoon 
east of the mountains however...mountain temperatures are forecast to 
gradually cool through the rest of the day. In fact...middle to late 
afternoon reading across the foothills and Piedmont may begin to 
drop with impressive cold air advection. 


Tonight...winds will subside somewhat except in the northern mountains (where 
tighter pressure gradient will continue through most of the ngt). The axis of upper 
trough will swing through area...W/ potent short wave energy. Guidance shows 
plenty of moisture but winds remaining backed to westerly or even west-southwesterly. It 
still luks like enough quantitative precipitation forecast and cold temperatures for at least 1-2" along the 
Tennessee/NC border. West/ a wind event preceding the snow...we will issue a 
Winter Weather Advisory for the Tennessee border counties for this evening through Thursday 
afternoon. Temperatures will drop readily in the cold air advection to the upper 20s to lower 30s 
mountains and mainly middle-upper 30s Piedmont. 


&& 


Short term /Thursday through Saturday/... 
as of 320 am Wednesday...deep trough lingers over east US with moist west to 
northwest flow continuing over the mountains Thursday-Thursday evening. Models are indicating 
longer duration of moist upslope flow in the colder air over the NC 
mountains so bumped up probability of precipitation Thursday afternoon-evening in line with latest trends. By 
the time the moisture moves east of the north mountains Thursday night...snowfall 
totals of 1-3 inches are possible...mainly for counties along the Tennessee 
border. 


Upper trough moves east late Thursday night-Friday with dry...high pressure 
building over the area at the surface. Surface high moves east by Friday afternoon 
which puts US in warm S flow. Afternoon highs will be a few degree above 
average. Warm...moist S flow picks up Friday night and clouds begin to 
increase over the area. A fast moving shortwave and associated cold front 
approach from the northwest Sat bringing an increasing chance of rain 
showers to the area. Look for highs a couple categories above average. 


&& 


Long term /Saturday night through Tuesday/... 
as of 320 am Wednesday...models in poor agreement with timing for 
the extended range but 500 mb shortwave and surface cold front should push S 
of area Sat night-sun with at least a chance of showers. Expect near 
average highs sun-Monday as high pressure builds over the area. GFS and 
European model (ecmwf) show a broad upper trough setting up over the east US with a 
shortwave and associated cold front diving toward the area from the northwest 
Monday night and Tuesday. Not much moisture expected with this system but 
will hold on to slight chance probability of precipitation. Look for near average temperatures Tuesday. 


&& 


Aviation /16z Wednesday through Sunday/... 
at kclt...cold front has pushed east past the terminal...with just some 
light showers west/ tempo MVFR restrictions for next couple hours. VFR 
level clouds will generally decrease in coverage...and visibility will be 
VFR through period. Southwesterly winds will increase to 15-20 knots around 
15-16z...with frequent gusts over 30 kts possible through the afternoon. 
Winds will subside this evening and remain southwesterly. 


Elsewhere...there will be some lingering very light showers through 14z 
or so. There is still potential for MVFR ceilings so I threw in a tempo. 
Outside the mountains...southwesterly winds will increase to 15-20 knots around 
15-16z...with frequent gusts over 30 kts possible through the afternoon. At 
kavl...the direction will change to northwesterly around midday or early afternoon 
and become gusty into the evening. Winds will subside this evening. 


Outlook...conditions should remain VFR Thursday and Friday with 
building high pressure. Saturday...a cold front will bring showers 
into the area...with the potential of restrictions. Drying high 
pressure builds in Sunday. 


&& 


Gsp watches/warnings/advisories... 
Georgia...Wind Advisory until midnight EST tonight for gaz010-017-018- 
026-028-029. 
NC...Wind Advisory until midnight EST tonight for ncz033-035>037- 
048>053-056>059-062>065-068>072-082-501>510. 
Winter Weather Advisory from 7 PM this evening to 7 PM EST 
Thursday for ncz033-048>052-058. 
SC...Wind Advisory until midnight EST tonight for scz001>014-019. 


&& 


$$ 
Synopsis...rb 
near term...Ned/Ark 
short term...rb 
long term...rb 
aviation...Arkansas