Weather

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Area forecast discussion 
National Weather Service Peachtree City Georgia 
259 PM EDT Friday Oct 10 2008 


Short term /tonight through Sunday night/... 


The short-term models are in fairly decent agreement...at least 
through the first 36 hours...on the evolution of the upper low and 
the surface high that will be impacting the resultant weather over 
the region. Upper ridge is building in over the southeast and with 
the upper low still in place...albeit weakening...the ridge's 
position is providing enough confluent flow over New England to 
allow the surface ridge to slide down the Appalachians beginning 
tonight. Between the easterly flow provided by the cad high and 
the moisture still in place from the upper low...have continued 
low probability of precipitation (slight chance to low chance) in southeast zones...and 
have also continued the abundant cloud cover that we have seen the 
past couple of days. Nighttime temperatures should remain higher than we 
should see this time of year...though highs shouldn't be 
abnormally low. 


As the upper low is drawn back east inland over the ridge...though 
still weakening...precipitation chances increase over the area somewhat 
Saturday into Sunday. GFS is dealing with some convective feedback 
but with isentropic upglide...the mechanisms are there for a good 
rain in some locations. The other thing to consider is the 
increasing pressure gradient as the surface ridge continues to 
build south...especially if quantitative precipitation forecast and latent heat release result in 
a surface reflection of the (weakening) upper low. End result... 
may be a bit breezy Saturday night and Sunday...especially up in 
the mountains. 


Other concern is temperatures on Sunday. NAM pushes the precipitation 
further south and east...clearing northeast Georgia out much more 
than the GFS. With much more rain...the GFS has much cooler 
temperatures (by >10 degrees in some locations) than the NAM. On 
the flip side...with the drier dewpoints and clear skies...the NAM 
is far cooler Sunday night than the GFS. Have taken a compromise 
for Sunday highs as the source of surface cold air advection will be modified 
somewhat and flow will be off the Atlantic...so even with the 
precipitation (according to the gfs) we might not get that cool. But will 
definitely have to see what the next run has and adjust if necessary. 


Long term /Monday through Friday/... 


Surface high has shifted further south on Monday...continuing to 
modify...as strong upper low approaches from the west. However... 
with the upper ridge in place...the bulk of the energy associated 
with the front should be shunted to the north and by midweek...we 
only get the weak stretched-out southern edge of the front. A bit 
of a pattern change setting up by the end of the week as a very 
large upper trough dominates the eastern two-thirds of the 
country...if not more...pushing the ridge into the Gulf. This will 
allow for intermittent shortwaves to reach at least into north 
Georgia as moisture is spun around the western edge of the high 
and into the bottom of the trough. Definitely some differences in 
the extended solutions with this fairly progressive pattern so do 
not have particularly high confidence in any one solution. We can 
expect a bit of a warm-up ahead of the front through mid-week... 
and then by the end of the week temperatures should begin to 
return to near normal again as the large trough builds in. 


&& 


Fire weather... 


Because of the easterly flow off the Atlantic...in addition to the 
clouds and possible precipitation especially in southeastern 
zones...no critical fire weather conditions are expected during 
the short-term. 




&& 


Preliminary point temps/pops... 
Athens 62 74 60 73 60 / 10 20 30 40 10 
Atlanta 64 76 63 74 61 / 5 10 30 30 10 
Blairsville 56 77 56 72 53 / 5 5 20 20 10 
Cartersville 61 78 61 75 60 / 5 5 20 30 10 
Columbus 66 79 66 78 66 / 5 10 20 30 10 
Gainesville 60 75 61 72 58 / 5 10 30 30 10 
Macon 65 76 66 77 64 / 10 20 30 40 10 
Rome 61 81 61 77 62 / 0 5 10 20 10 
Peachtree City 61 78 61 74 63 / 5 10 30 30 10 
Vidalia 66 77 66 78 62 / 20 30 40 50 10 


&& 


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


$$ 


Tdp