110 
fxus63 kjkl 211200 aaa 
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Area forecast discussion...updated 
National Weather Service Jackson Kentucky 
700 am EST Sat Nov 21 2009 


Short term.../today through Monday/ 


Models solutions are in reasonable agreement with evolution of upper 
air pattern. Weak short wave passing through the Great Lakes region 
will continue to track eastward. A more significant low passing 
through Texas will take aim at eastern Kentucky...passing through as an 
open wave by late Sunday or Sunday night. Model trends have been 
slower and weaker with this feature with respect to our weather. This 
system pulls off to the northeast by the end of the period. At the 
surface...low pressure center over the Gulf morphs into nothing more than 
an inverted trough over our area in response to opening wave 
traversing the Tennessee Valley region Sunday. For isc grids...leaned more 
towards the NAM for the first 24 hours...thereafter moving closer to 
a blend of the GFS and European model (ecmwf) solutions for the remainder of the 
period. 


These latest trends have a significant affect on sensible weather... 
particularly with respect to probability of precipitation and precipitation. In general had to 
trend lower with probability of precipitation through the period...and decrease quantitative precipitation forecast totals. 
Otherwise...only made some tweaks to elements to come into line with 
latest thoughts. 


Long term.../Monday night through Friday/ 


Models have been all over the board with respective surface solutions. 
However...models continue to show decent agreement with overall 
upper level pattern evolution. Weak short wave energy tracks quickly 
through the Ohio Valley region Monday night...just as a more potent 
low pressure system drops out of the intermountain region into the 
plains. This system moving out of the plains will be our next 
weather maker...most likely affecting our area from middle week through 
the Thanksgiving Holiday. The European model (ecmwf) has a slower...more southerly 
track than the GFS and swings a frontal boundary through our area 
late Wednesday...about 24 hours slower than earlier runs. The GFS 
has trended slower as well...with this front moving through our area 
Tuesday night into Wednesday morning...or about 12 hours slower. Made 
appropriate changes to the forecast to account for these latest 
trends...though confidence is overall scenario of events is low at 
best. Most interestingly...both the GFS and European model (ecmwf) show a significant 
band of wrap around moisture affecting our area behind the main 
systems departure on Thanksgiving. The GFS column profiles support 
the potential of some snow late Thursday into Thursday night. 
However...the European model (ecmwf) is quite a bit warmer. At this time preferred the warmer 
European model (ecmwf) solution and will leave any mention of the white stuff out of 
the forecast. 


&& 


Aviation.../12z to 12z/...updated 


Aside from the brief period of MVFR fog in the deeper valleys...and 
sme...around dawn this morning...VFR conditions will be the rule 
through the taf period as high pressure keeps the area clear below 
12k feet. Just a scattered to broken layer of high clouds of varying thickness 
is expected through Sunday morning. Winds will be light...generally 
from the northeast through the period...but picking up from the east 
at 5 to 10 kts later tonight. 


&& 


Jkl watches/warnings/advisories...none. 


&& 


$$ 


Short term...ray 
long term....ray 
aviation...greif