100 
fxus64 kmrx 212000 
afdmrx 


Area forecast discussion 
National Weather Service Morristown Tennessee 
300 PM EST Sat Nov 21 2009 


Short term...(tonight through sunday)...low pressure analyzed along 
the south Louisiana coast at 19z...continues to push middle-high level 
clouds north toward the Tennessee Valley region. Will see a gradual 
increase in middle- high level clouds overnight from the southwest to 
the northeast across the area. Would not also rule out a stray 
-shra/rain toward sunrise in south and southeast counties. Temperatures look 
generally good as per going forecast...and like GFS/NAM solution for 
southwest virgina/Tri Cities area with lesser amounts of clouds 
there. Will drop precipitation chances down considerably forecast area wide 
tonight to account for slower solution based upon current trending 
and as per GFS/NAM models. 


GFS/NAM models continue to differ in regards to the timing of the 
precipitation moving into the forecast area on Sunday. Will follow a 
compromise more toward the sref model and in between GFS/NAM 
solution for Sunday. Will gradually increase probability of precipitation across the south 
and central portions of the area on Sunday...with chance probability of precipitation being 
the rule from just north to tys-in between cha/tys. Will go with 
probability of precipitation becoming more toward the likely category for cha area and 
southwest North Carolina counties...especially by afternoon. 


Temperatures look generally good as per going forecast for Sunday...and 
accepted at this time. 


Long term...(sunday night through saturday)...weakening Gulf Coast 
system should be centered across the Florida Panhandle by Sunday 
evening with moisture spreading across east Tennessee and SW NC and finally 
into SW Virginia. System will be a little slower to move out of the region 
Monday and Monday night so held on to higher probability of precipitation Monday. Best 
chance of rain will be Sunday night into early Monday. GFS has weak 
upper low across middle Tennessee Sunday night with rainfall fairly uniform 
across forecast area but NAM model has higher amounts east closer to 
weak surface low that redevelops off southeast coast Sunday night and 
Monday. Prefer the NAM solution with higher probability of precipitation east then shifting 
to northeast early Monday and larger quantitative precipitation forecast numbers east in the 
mountains. Models hint at brief ridging Tuesday and then a quick 
moving system from the northwest Tuesday night. Wednesday dries out again 
but another system that is quick on its heels should affect the 
region Wednesday night into Friday and possibly longer. Snow 
showers will be possible at night with freezing levels lowering as a 
trough develops over the eastern states Thursday and Friday. 


Preliminary point temps/pops... 
Chattanooga Airport, Tennessee 43 55 45 58 45 / 30 60 30 20 10 
Knoxville McGhee Tyson Airport, Tennessee 41 55 43 57 42 / 20 60 40 20 10 
Oak Ridge, Tennessee 40 55 44 57 43 / 20 60 40 20 10 
Tri Cities Airport, Tennessee 34 54 41 55 39 / 10 50 50 30 10 


&& 


Mrx watches/warnings/advisories... 
NC...none. 
Tennessee...none. 
Virginia...none. 


&& 


$$ 


Tt/dew point