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Area forecast discussion...updated 
National Weather Service Peachtree City Georgia 
545 PM EST Sat Nov 21 2009 


Short term /tonight through Monday night/... 
current radar loop shows some light showers moving in from the SW 
with most of central Georgia having seen 0.01 to 0.03 inches. This is 
just the initial push of moisture from the developing low pressure 
system along the Gulf Coast. Models are showing another 1 to 1.5 
inches expected across the state through Monday morning which will 
not be enough to cause any more flooding concerns. The models show 
the surface low along the la Gulf Coast deepening as it tracks east 
tonight...hugging the Gulf Coast through Monday morning. This low 
will begin slowly weakening Sunday as it moves up the East Coast 
through Tuesday morning. By then it will have pushed most of its 
moisture across the region and up into the Middle Atlantic States. A 
wedge of high pressure is also beginning to deepen across the 
eastern Seaboard this afternoon and it will push down into north Georgia 
tonight. This wedge should keep the atmosphere over the state fairly 
stable so not expecting any thunderstorms tonight through Monday 
morning. Depending on just how strong this wedge is we could see 
light rain or drizzle continue through Monday afternoon. With this 
wedge building in expect temperatures across north and most of central Georgia 
to stay in the 50s all day sun and most of Monday. Have gone well 
below guidance especially across central Georgia Monday. This wedge will 
begin to erode Monday so temperatures may rebound some...mainly across west 
and central portions of the forecast area. 


Long term /Tuesday through Saturday/... 
GFS/European model (ecmwf) differ a bit in the extended periods. GFS stronger with 
the developing low over the Midwest...but further north than the 
European model (ecmwf). European model (ecmwf) also showing better moisture return ahead of the next 
system Tuesday and Tuesday night. Canadian model is in better 
agreement with the GFS as far as the positioning of the upper 
low...but trends toward the European model (ecmwf) surface analysis which keeps the 
weak wedging and Atlantic moisture across the area through Tuesday. 
The cold front approaches the forecast area by Wednesday afternoon 
and exits the forecast area on Thursday with broad high pressure 
building in for Friday. Overall confidence in extended periods are 
low but will blend the models holding onto clouds and low chance 
probability of precipitation Tuesday night and Wednesday. 


&& 


Aviation... 
primary concern is timing of clouds...precip...and IFR conditions 
next 12 hours. Although light precipitation south of katl still observed on 
radar...surface precipitation intensity very light and visibility/ceiling restrictions 
remain solidly VFR. Based on Sat and radar trends and short range 
model forecasts...expect this trend of very light and widely scattered rain showers to 
continue through around 12z when bulk of isentropic lift prognosticated to 
commence. Precipitation and lower ceilings should move in from the SW reaching 
kcsg around 09z...katl around 12z and kahn around 15z. Have already 
adjusted katl taf with this timing. IFR conditions likely within an 
hour of onset of precipitation and should remain steady or deteriorate to 
LIFR during the day and persist through at least 06z Monday even after 
precipitation prognosticated to taper off. MDT surface winds will remain easterly at 
8-13kts through the event. 


Snelson 


&& 


Preliminary point temps/pops... 
Athens 46 48 43 53 46 / 40 80 60 30 10 
Atlanta 47 52 44 55 48 / 60 80 40 20 5 
Blairsville 39 49 45 50 42 / 30 70 50 40 10 
Cartersville 45 53 45 52 46 / 50 80 50 20 5 
Columbus 52 58 50 62 49 / 100 80 30 5 10 
Gainesville 45 48 42 49 46 / 40 80 50 30 5 
Macon 50 56 46 59 46 / 80 90 30 10 10 
Rome 43 51 48 57 46 / 50 80 50 20 5 
Peachtree City 47 51 46 59 43 / 70 80 40 20 5 
Vidalia 49 57 46 63 48 / 60 90 50 5 5 


&& 


Ffc watches/warnings/advisories... 
none. 
&& 


$$ 


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