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Area forecast discussion 
National Weather Service Twin Cities/Chanhassen Minnesota
1241 PM CDT Tuesday Oct 21 2014

Updated for 18z aviation discussion...
issued at 1230 PM CDT Tuesday Oct 21 2014

&&

Short term...(today and tonight)
issued at 319 am CDT Tuesday Oct 21 2014

Today-tonight...surface analysis shows an elongated north-S oriented area
of high pressure atop the area which will shift off to the east during
the day today...then stall out over the Great Lakes tonight.
Aloft...a ridge of high pressure straddling the border of Minnesota and
western Dakotas this morning will slowly slide east across Minnesota and WI
during the day today...also expected to stall out tonight over the
western Great Lakes southward through the middle Mississippi River
valley. This deep ridging combination will keep skies mostly clear
for the period through tonight...aside from some wraparound
moisture from a departing upper level low pressure center over the
eastern Great Lakes...bringing stratocu down over mainly eastern
and northern WI...possibly as far west as Barron/Rusk/Chippewa
counties in western WI. This cloud cover may linger for much of
the day in the far eastern portion of the mpx County warning forecast area while fair
weather cumulus clouds develop over eastern into central Minnesota. Cold air
advection in advance of the incoming ridge will keep highs in the
low-middle 50s for western WI. In contrast to this...modest warm air
advection will occur for central-western Minnesota on the backside of the
upper ridge where highs will range through the 60s...and possibly
to near 70 along the South Dakota border. For tonight...the best radiational
cooling conditions will be over western WI where lows will drop to
near the freezing mark. The spread in lows to central-western Minnesota
will be quite large as warmer return flow will have much more
influence out west. Lows tonight in western Minnesota will only drop to
the middle-upper 40s.

Long term...(wednesday through monday)
issued at 319 am CDT Tuesday Oct 21 2014

Early morning water vapor imagery showed a prominent circulation
moving east across northern California into Nevada. This
circulation is in association with an upper level shortwave that
is the main concern for the long term forecast period. This wave
is expected to move east-northeast across the western Continental U.S. And produce rain
across the forecast area from Wednesday through Thursday that will move west
to east across the area. There remain model differences in timing
and amounts expected that still need to be sorted out. The GFS
moves the energy through the fastest...while the NAM is several
hours slower with the expansion of isentropic ascent and
saturation across the forecast area. Rainfall amounts generally look to be
less than 0.5". Overall...forecaster confidence is below average
at this time due to these differences.

Once this system passes...upper level ridging will ensue across
the upper Midwest. Little change was made to the forecast beyond
Friday...as warm and dry conditions still look like a good bet.
Went warmer than blended guidance on Friday and Sunday as
temperatures warm under the ridge. European model (ecmwf) and GFS still indicate
cyclogenesis on the Lee of The Rockies toward the end of the
weekend with spatial and temporal differences in the evolution of
the system. This system gives US our next opportunity at
precipitation...most likely at the very end of the weekend into early
next week.

&&

Aviation...(for the 18z tafs through 18z Wednesday afternoon)
issued at 1230 PM CDT Tuesday Oct 21 2014

VFR conditions today and tonight will give way to clouds Wednesday
morning across western Minnesota. Moisture profiles from several models
show the potential for MVFR clouds at kaxn...kstc...and krwf. Winds
will continue southeasterly throughout the period.

Kmsp...
VFR conditions throughout. MVFR ceilings are possible Wednesday...but
at this time do not have the confidence to put MVFR conditions in
the tafs. Looking ahead...rain will move in from the west around
00z Thursday.

/Outlook for kmsp/
Thursday...VFR with MVFR/-shra early. Winds south-southeast at 10g20kts.
Friday...VFR. Winds south-southwest at 5-10kts.
Sat...VFR. Winds northwest at 5-10kts.

&&

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

$$

Short term...jpc
long term...speed
aviation...jrb

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