679 
fxus62 kcae 202318 
afdcae 


Area forecast discussion 
National Weather Service Columbia SC 
718 PM EDT Sat Mar 20 2010 


Synopsis... 
high pressure centered off the southeast coast will dominate 
through tonight. Moisture will increase Sunday ahead of an 
approaching front. The front will move through the area Sunday 
night. 


&& 


Near term /through Sunday/... 
high pressure off the coast will continue to dominate tonight. The 
air mass will remain dry but an increase in boundary layer wind 
will help hold up temperatures. Used the guidance consensus for 
the low temperature forecast. 


&& 


Short term /Sunday night through Monday night/... 
little change made to current forecast. Still timing issues with 
GFS faster than NAM developing rain in the area Sunday afternoon. 
Latest sref suggest highest probability of precipitation Sunday night... 


Moisture will be on the increase Sunday afternoon ahead of the 
occluded front. An average of the NAM and GFS MOS support likely 
probability of precipitation in the southwest to chance in the northeast section. The 
greatest shower chance should be Sunday night associated with 
convergence along the front and an 850 mb jet. Shear will be high 
supporting some possibility of severe thunderstorms...but 
instability still appears to be a limiting factor. The NAM 
continues to keep surface-based Li/S above zero and this appears 
reasonable with the very cold middle-level temperatures associated 
with the upper low remaining west of the region and convection 
near the coast limiting moisture transport northward and into the 
forecast area. The NAM and GFS are consistent forecasting light 
rainfall amounts of mainly one- quarter of an inch or less. Upper 
low moving over the area Monday/Monday night. Considerable clouds 
expected with a few showers. 


&& 


Long term /Tuesday through Saturday/... 
the GFS/European model (ecmwf) shows a dry pattern until the end of the period when 
moisture appears to increase near another low pressure system. 


&& 


Aviation /00z Sunday through Thursday/... 
scattered diurnal cloudiness expected to dissipate early this 
evening. Smoke from area wildfires may affect visibilities in some 
locations through early this evening. Sea breeze 
boundary...currently seen on radar and satellite across the 
southern tier of the forecast area...will move north some this 
evening before dissipating. This may allow a slight wind shift 
with some temporary increase in wind speed early this evening. 
Low level air is still fairly dry...so will not indicate any 
stratus developing late tonight. Will throw in ws mention 
overnight due to indications of increasing boundary layer wind. 
Weather system to our west will shift east through Sunday. It 
appears that some weak isentropic lift will develop Sunday and 
provide some light showers...and possibly MVFR ceilings...by 
afternoon. 


Extended aviation outlook...the main front with a band of 
showers...and possibly thunderstorms...will roll across the 
forecast area from west to east Sunday night...after 00z Monday. 
Some of the storms could produce strong gusty winds. An upper 
level low will slowly move east over the region Monday...providing 
some cloudiness and a few showers...though drier low level air 
should keep the ceilings VFR or high end MVFR. Breezy conditions 
possible Tuesday. No significant impacts to aviation expected 
Wednesday and Thursday. 


&& 


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


&& 


$$ 
Aviation...dcm