Weather

015 
fxus63 kmpx 110842 
afdmpx 


Area forecast discussion 
National Weather Service Twin Cities/Chanhassen Minnesota 
342 am CDT Sat Oct 11 2008 


Discussion... 
forecast concern near term...potential for rain showers/thunderstorms and rain mainly across 
northwest County Warning Area...and temperature trends. Rather potent front across 
far western County Warning Area this morning. Good temperature contrast indicated 
this morning. Models indicate that this boundary will remain 
nearly stationary today. This will likely generate high bust 
potential in maximum temperatures in the vicinity of this boundary. Few 
-shra lifting north across mainly northern portion of the County Warning Area and 
satellite showing some high cloud enhancement over eastern South 
Dakota into northwest Minnesota associated with short wave moving across 
eastern South Dakota this morning. This may yet generate some 
showers into mainly northwest County Warning Area this morning. Will maintain some 
low probability of precipitation for this. Overnight...models move another short wave 
northeast over mainly northwest County Warning Area overnight. As this moves 
through...ridging aloft develops again in response to its passage 
and deepening trough over the western Continental U.S.. the surface boundary redevelops 
back west into the western Dakotas overnight. This will draw in 
some warmer air to most of the County Warning Area tonight...keeping lows mainly 
in the 50s. 


Models then trend jet energy lifting northeast as the upper low 
begins to lift northeast across the Dakotas. The surface cold front moves 
into western Minnesota by late Sunday afternoon. Enough dynamic forcing 
moves across the western areas to generate likely probability of precipitation again during 
the afternoon. It does appear model forecast precipitable water 
values a bit high initially. More moisture will be lifted 
northeast across the plains and along the cold front Sunday night 
and Monday however. Models indicate some subtropical moisture 
should lift northeast as Norbert remnants move into New Mexico 
region later Sunday. Surface cdnft then moves slowly east Sunday night 
and Monday. Will continue with high probability of precipitation as this moves east. 
Marginal instability asscoaited with the fnt moving through...with 
low-middle k index values and 850 mb Li sligtly negative. Should be 
enough for some widely scattered thunderstorms and rain along fnt into Sunday night and 
Monday. Much colder air follows the front...and should dry out 
western potion of the County Warning Area by Monday evening. 


Models are trending slower frontal movement across western 
Wisconsin Monday night into Tuesday. GFS is deeper and therefore 
slower with the trough lifting north and east across the area. 
Will hold onto some low end probability of precipitation in case this feature slows 
further. 21z sref and 00z GFS ensembles were holding onto some 
probability of precipitation into early Tuesday as well. 


&& 


Aviation.../06z taf issuance/ 


Generally VFR conditions during the forecast period...except vicinity 
kaxn where MVFR ceilings could develop...due to frontal boundary in 
the area. Remaining isentropic lift overnight could cause a few 
showers in this area as well. Otherwise occasional broken ceilings 050-060 
could develop in the weak warm advection pattern over the Minnesota 
forecast area overnight into Saturday morning. An upper level wave 
is then forecast to move across mainly the western parts of the 
area by Saturday afternoon and evening causing a few showers vicinity 
kaxn...kstc Saturday evening. Small chance thunder but too isolated 
to include in taf at this point. Mainly middle level ceilings Saturday 
afternoon into the evening for all sites except kaxn and kstc as 
frontal boundary remains over the northwest third of the forecast area. 


&& 


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


$$ 


Dwe/trh