154 
fxus64 kmrx 070743 
afdmrx 


Area forecast discussion 
National Weather Service Morristown Tennessee 
343 am EDT Tuesday Oct 7 2008 


Short term...(today and tonight)...expect gradual changes today 
ahead of the approaching low pressure system and cold front. Not 
certain if clouds increase fast enough to keep maximum temperatures down to 
the cooler GFS MOS numbers...so I opted to go closer to a blend of 
NAM-WRF and GFS. Timing for convective precipitation (showers 
mainly) was generally on track in previous forecast grids... 
following a GFS and European model (ecmwf) blend on timing late tonight. 


Adjusted quantitative precipitation forecast grids slightly...preferring to stay below the HPC quantitative precipitation forecast 
amounts...although pattern changes late tonight should advect Gulf 
moisture northward...with good isentropic lift developing between 06z 
and 12z Wednesday. MOS mins tonight similar and I saw little reason 
to differ much from GFS MOS choices. 


Otherwise...NAM-WRF handling of upper low so far SW would slow down 
frontal passage...and keep rain chances in longer than other 
solutions. However...NAM-WRF seemed to be an outlier. 


Latest surface observations do not indicate any fog significant 
enough to justify including in forecast grids and/or zfpmrx for 
this morning. 




Long term...(wednesday through monday)...models and ensembles are 
in reasonable good agreement through the long-term period. Upper 
trough currently progressing through Central Plains is projected to 
amplify into a closed low as it approaches the southern appalachian 
region. Mav guidance continues with categorical probability of precipitation for Wednesday 
and there is no compelling reason to significantly deviate from this 
projection. This feature is projected to meander around the 
southeastern Continental U.S. Into the upcoming weekend providing somewhat 
unsettled weather through Friday. Dry weather returns through the 
balance of the long term as upper ridge builds in behind upper low. 
For temperatures...generally followed mav/gfsx guidance fairly closely. 




&& 


Preliminary point temps/pops... 
Chattanooga Airport, Tennessee 79 62 68 58 79 / 10 90 100 30 20 
Knoxville McGhee Tyson Airport, Tennessee 80 58 68 58 78 / 10 60 100 50 30 
Oak Ridge, Tennessee 80 58 68 59 78 / 10 70 100 50 20 
Tri Cities Airport, Tennessee 79 52 67 58 75 / 0 20 90 80 40 


&& 


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


$$ 


Tg/lcm