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Area forecast discussion 
National Weather Service Columbia SC 
346 am EDT Tuesday Oct 7 2008 


Synopsis... 
high pressure will remain over the region today ensuring another 
fair day. Moisture will be on the increase Wednesday ahead of the 
next weather system that will slowly move through. 


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Near term /through tonight/... 
fair and dry weather will continue with high pressure along the East 
Coast. Expect gradually increasing high level cloudiness. 


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Short term /Wednesday through Friday night/... 
upper trough over the central Continental U.S. To shift east into the miss 
valley Wednesday. Models agree on developing a closed upper low somewhere 
in the vicinity of the lower miss valley/deep south/southeast US Wednesday/Wednesday 
nt. There are disagreements among the models with regards to 
position and timing. 00z GFS ensemble MOS indicating a wide range of 
probability of precipitation and high Standard deviations. Therefore...uncertainty is 
considerable. NAM keeps the upper low to our SW Thursday nt/Fri. The GFS 
moves it slowly east across our region through Friday. 00z NAM and 
GFS MOS both provide categorical probability of precipitation for Wednesday nt. However...short 
range ensemble probability of precipitation and quantitative precipitation forecast probabilities do not exceed 50 percent. 
HPC prefers a GFS/European model (ecmwf) compromise. Going forecast has likely probability of precipitation 
for Wednesday nt. At this time given uncertainity...would rather not go 
categorical probability of precipitation or make considerable changes to the going 
forecast. Will maintain likely probability of precipitation Wednesday nt/Thu. 


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Long term /Saturday through Monday/... 
considerable uncertainty continues regarding the aforementioned 
system. GFS stalls the upper and surface lows just to our 
east through Sunday. The European model (ecmwf) shifts it south. The Canadian model 
keeps it moving E/NE. The going forecast is dry. After collaboration 
with adjacent weather forecast office...decided a small pop was in order through 
Sunday. 


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Aviation /06z Tuesday through Saturday/... 
the fog potential appears less late tonight compared to last night. 
Expect an increase in boundary layer winds toward daybreak. 
The NAM and GFS show the pressure gradient becoming tighter during 
the early morning hours as the ridge builds into the area from 
the north. The sref guidance plus the met and mav MOS 
temperature-dew point temperature spreads support VFR conditions 
early this morning. Visibilities already around 6 miles at most taf sites. 
Could see visibilities lower to 2 or 3 miles before boundary layer winds 
increase. Should see patches of middle and high level cloud move 
through the area this morning. After 13z...the dry ridging should 
maintain VFR conditions through the day Tuesday. 


Extended outlook...widespread MVFR or IFR conditions may occur 
Wednesday night through Friday associated with low pressure moving 
into the area. 


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Cae watches/warnings/advisories... 
SC...none. 
Georgia...none. 


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$$