Area Forecast Discussion
Issued by NWS Twin Cities, MN

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FXUS63 KMPX 300354

Area Forecast Discussion
National Weather Service Twin Cities/Chanhassen MN
954 PM CST Tue Nov 29 2016

.SHORT TERM...(This evening through Wednesday)
Issued at 215 PM CST Tue Nov 29 2016

Early afternoon water vapor imagery together with GFS 500mb heights
and surface obs show a broad upper level trough across the central
Conus, with the center of an upper level low across central
Minnesota. Over the next 36 hours this upper level low will slowly
meander to the east southeast. Areas of enhanced vorticity will lead
to widespread light precipitation. Forecast soundings show deep
saturation and no elevated warm layer, so the precipitation type
will depend solely on the boundary and surface layer temps, and for
that reason expecting a rain/snow mix. The best forcing for ascent
will be along the Minnesota River valley and I-90, so have increased
pops considerably for those locations. QPF amounts are less than a
tenth of an inch over 6 hours, so snowfall amounts will also be
light, with western Minnesota seeing the maybe a couple of inches.
Areas in eastern Minnesota and western Wisconsin will see little if
any precipitation.

.LONG TERM...(Wednesday night through Tuesday)
Issued at 215 PM CST Tue Nov 29 2016

The longer term trends are continuing to indicate a more active
pattern developing mainly later in the weekend into next week.

In the interim...we have the Wednesday night upper low to spread
east taking the light snow...drizzle/flurries with it through
Thursday morning. It does look like clouds will remain through
Thursday and into Friday. Temperatures should remain above normal
through this period...with small diurnal change continuing.

The next threat of snow arrive Sunday as another weak wave moves
east in the northern stream. Critical thickness values for this
period do increase there remains the potential for a
rain/snow mix. The various deterministic runs diverge some on
timing of this wave and what follows into early next week. We do
see some consensus developing for a significant trough developing
over the western CONUS by midweek as cold Canadian air drops
south over the rockies. This aids in the development of what could
be a significant winter storm for the Great Lakes/Upper Midwest
region by Wed/Thu 12.07 through 12.09. Both the 12z GFS and ECMWF
show the potential for a deep TX/OK panhandle low developing and
ejecting northeast across IA/SRN MN/WI region. It does appear that
it should be mainly snow as enough cold air is in place initially.
We will need to monitor this model trend closely the next few days
to see if it continues.


.AVIATION...(For the 06Z TAFS through 06Z Wednesday night)
Issued at 954 PM CST Tue Nov 29 2016

MVFR/IFR ceilings will prevail through the period as a vertically
stacked low pressure system over MN moves slowly east. An
extensive area of light precipitation/mist under and to the west
of the low pressure system will cause MVFR/IFR visibilities as
well. These are most prevalent now to the west of KMSP and KSTC,
but they will slide east into western WI overnight. Winds SSE
ahead of the low and WNW to the rear of the low with speeds less
than 10 knots.

KMSP...Ceilings dropping to IFR by TAF issuance and continuing
there much of the day on Wednesday. Light rain will be the
dominate weather feature overnight, but some light snow may mix an
hour or two either side of daybreak. Surface temperatures to
remain above 34 degrees with no accumulation expected.
Ceiling/visibilities improving late tomorrow afternoon and evening
but still remaining MVFR.

Thu...MVFR. Wind NW 5-10 kts.
Fri...MVFR. Wind NW 5-10 kts.
Sat...VFR with MVFR possible. Wind W at 10 kts




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