046 
fxus63 kmpx 212049 
afdmpx 


Area forecast discussion 
National Weather Service Twin Cities/Chanhassen Minnesota 
249 PM CST Friday Nov 21 2008 


Discussion... 
the shortwave trough entering the western Dakotas per 20z water 
vapor imagery will be the focus locally over the next 18 
hours...as it closes off and slides east/southeast across southern 
Minnesota. Associated 850-700mb Omega and 2d frontogenesis Blossom over 
the southern County Warning Area around 03z...but expect the bulk of the snowfall 
to occur between 06z and 12z when the low level saturation occurs. 
The dynamics...while briefly impressive...are somewhat out of sync with the 
arrival of the low level moisture...so snowfall accumulations of 
one inch or less still appear reasonable along/south of the Minnesota 
River Valley. This is supported by NAM/GFS/RUC prognosticated Cobb 
outputs for kfrm and krwf. 


Temperatures at western County Warning Area locations will likely remain elevated 
in the low 20s tonight...especially considering the cloud cover 
and warm air advection. Eastern areas will have the potential to 
dip into the single digits again...especially across west central 
WI. Low/middle clouds will linger on Saturday...but temperatures will 
moderate to around freezing. 


Temperatures will warm even more on Sunday ahead of an approaching 
trough...with highs in the upper 30s and lower 40s expected. The 
related cold front passes across the County Warning Area on Sunday 
afternoon/night...as shortwave energy on the western periphery of 
an amplifying eastern Continental U.S. Trough streams across Minnesota and WI. The 
deeper moisture will be present across the eastern County Warning Area where 30 
probability of precipitation were preserved...while 20 probability of precipitation were adequate elsewhere. 


The extended portion of the forecast will feature dry weather with 
near to above normal temperatures through the Thanksgiving 
Holiday...as the upper Midwest experiences middle level ridging while wedged 
between cyclones over both coasts. 




&& 


Aviation.../18z taf issuance/ 


VFR conditions still prevailing into tonight with departing high 
pressure..and dry south-southeast flow on the back side of the high. However...a 
significant wave over Montana is forecast to track east-southeast toward southeast South Dakota 
and northwest Iowa later tonight. This will cause some snow over SW Minnesota and 
far southern Minnesota after midnight. Ceilings will lower to MVFR at 
krwf with IFR visibilities possible for a few hours after 09z. MVFR or 
low VFR ceilings will also spread into parts of central 
Minnesota...including kaxn...kstc...and kmsp. This will occur mainly 
during the last part of the forecast period. At this time...snow 
is forecast only for krwf...but very light snow with p6sm 
conditions could affect kmsp and kstc Saturday morning as well. 
South-southeast winds will increase but speeds will mainly be less than 15 
knots sustained. Best chance for higher speeds will be at krwf and 
kaxn. 


&& 


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


$$ 


Ls/jpr