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Area forecast discussion...updated 
National Weather Service Nashville Tennessee 
1012 am CST Sat Nov 21 2009 


Update... 
at middle morning...surface analysis showed a ridge of high pressure 
extending from north Illinois...east-southeast to Virginia. Mostly some thin high clouds 
across the area at this time. Infrared satellite loop shows thicker 
clouds over MS. But as they move NE toward the midstate...thinning 
occurs as the clouds move into the weak northwest/southeast upper level ridge 
over the area. I expect this trend will continue most of this 
afternoon. 


Morning 850 mb analysis showed high pressure centered over west Kentucky/northwest 
Tennessee...with some cold advection occurring over the middle state. But 
model forecasts show as a whole...temperatures at 850 mb will change very 
little during the day today. 


I'll back off on the cloud forecast somewhat for this afternoon. 
And due to a tad more sunshine now expected...will raise forecast 
temperatures just a tad. 


Updated forecasts will be issued shortly. 


&& 


Previous discussion... /issued 341 am CST Sat Nov 21 2009/ 


Discussion...no significant weather was occurring in middle Tennessee this 
morning with surface high pressure over the region. Broken-overcast high 
clouds from the Gulf Coast low were spreading across the area. 
Temperatures were in the middle 30s to middle 40s. 


Main concern for this forecast period is the Gulf low pressure 
system. Models show the low moving across the southeast states 
this weekend...with possible showers for middle Tennessee. Latest GFS has 
flipped to a much farther south track than previous runs...and 
more in line with the more consistent European model (ecmwf). Even with this 
track...models still show moisture and some light rain moving 
into middle Tennessee...mainly Saturday night into Sunday. Generally...probability of precipitation 
will range from around 20 percent northwest to about 50 percent 
southeast. Rainfall amounts should be less than one quarter inch 
most areas. 


Lots of low level moisture is indicated through Sunday night all 
areas and even into Monday for the east half. A northern stream 
shortwave will clip the area Monday...so some lingering drizzle or 
showers possible Sunday night into Monday. There will be a dry 
period late Monday and Monday night...then a cold front will bring 
a small chance for showers Tuesday. A reinforcing shot of cooler 
air is expected by Thanksgiving with cool and dry weather to follow. 


&& 


Ohx watches/warnings/advisories... 
none. 
&& 


$$ 
Steigerwaldt