402 
fxus63 kmpx 231754 aaa 
afdmpx 


Area forecast discussion...updated for 18z taf 
National Weather Service Twin Cities/Chanhassen Minnesota 
1155 am CST Monday Nov 23 2009 


Discussion...issued 322 am CST 
the forecast challenges this period are precipitation chances and 
precipitation transition over to snow before Thanksgiving evening. 
In the near term...a nearly stationary front over central Minnesota...will 
move little today as a weak surface trough over the Central Plains 
drifts slowly east over the Midwest through Tuesday. 
Moist and warm air continue to lift north over the frontal boundary 
across the upper Midwest. Light rain should begin to push out of 
south central Minnesota and western Wisconsin later this morning with 
lingering light rain or drizzle over the rest of the forecast area 
through the remainder of the day. 


The models are in general agreement in the medium range... 
models have been consistent from run to run with upper low over the 
Central Plains...lifting northeast over the lower Great Lakes by 
Wednesday morning. Stronger upper level trough over the Pacific 
northwest...will begin to carve out a stronger trough over the 
northern plains/upper Midwest by Wednesday. 


The Gem-nhem model blend indicates the precipitation should be 
mainly rain through Tuesday...then become a mixture of rain or 
snow over portions of west central Minnesota Tuesday night then 
switch over to all snow over the entire forecast area on Wednesday 
as colder air sinks over the Midwest. 


Thanksgiving day and Friday...looks cold and dry as a surface ridge 
builds east over the upper Midwest during the period. 


&& 


Aviation.../18z taf issuance/ 


Precipitation slowly dmnshg far east Minnesota into wc WI as shortwave lifts NE through area. 
Even in precipitation...ceilings have gnrly remained VFR. Vicinity inverted trough near 
Minnesota/Dakotas brdr conds remain IFR...and will likely remain so through taf 
prd...affecting mainly axn in the short term. As trough mvs ewrd this 
evening/tnght IFR conds will accompany it...with IFR conds not expected to 
reach msp until after 06z. WV imagery shws shortwave rounding base of trough 
in Colorado with precipitation expanding across west into cntl Nebraska. This surge of 
precipitation should spred into rwf area by 03z and msp after 06z. Not xpctg any 
change to snow until after this taf prd. 


&& 


Mpx watches/warnings/advisories... 
Minnesota...none. 
WI...none. 
&& 


$$ 


Jvm/bap