Area Forecast Discussion
Issued by NWS Twin Cities, MN

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FXUS63 KMPX 231147

Area Forecast Discussion
National Weather Service Twin Cities/Chanhassen MN
647 AM CDT Mon Oct 23 2017

.Updated for 12Z Aviation Discussion...
Issued at 639 AM CDT Mon Oct 23 2017


.SHORT TERM...(Today and tonight)
Issued at 429 AM CDT Mon Oct 23 2017

Strong winds will develop today as a cold front pushes through the
region. Could see gusts 30 to 40 mph, especially in western and
southern Minnesota. Later tonight another surge of cold air will
move through the region, and this should result in stronger winds
overnight, with gusts 35 to 45 mph possible, especially in the
open areas of central Minnesota. Did not issue a wind advisory for
either of these since the first event appears very marginal, and
the second event is further off in the future.

A very powerful storm system will develop over the next 36 hours
across the Great Lakes region as a broad upper level trough with a
textbook PV signature merges with a cutoff low over the Tennessee
River Valley. Once this merger takes place, expect to see rapid
intensification of a surface low that will have a minimum sea
level pressure in the mid 990s this afternoon drop down to near
980 by Tuesday morning. As this surface low deepens, cold air
advection will move across the Upper Midwest and destabilize the
boundary layer. The combination of the winds from the surface
pressure gradient, together with the momentum transfer of the cold
air advection should lead to a realization of the strong winds
shown in the forecast soundings overnight. Despite the fact that
strong winds overnight are more difficult to realize than during
the day, have reason to believe that this set up will over-achieve
and could see the 45kt gusts shown in the forecast soundings
observed at the surface. Will likely need a wind advisory for
later this evening and overnight, but did not issue one at this
time for reasons mentioned above.

One other item of note is the increase in pops east of I-35 and
especially in western Wisconsin later this evening and overnight
as a shortwave moves across the region.

.LONG TERM...(Tuesday through Sunday)
Issued at 429 AM CDT Mon Oct 23 2017

The active weather pattern will continue into the extended
forecast as shortwave troughs march across northern North America
at a fairly high frequency. This will lead to breezy conditions as
surface highs and lows follow in step from west to east. Of
particular note is the shortwave for Thursday and Friday.

The ECMWF is farthest south and slowest with this system and
develops a hefty band of snow on the northern side of the surface
low track. Meanwhile the GFS and Gem are farther to the north and
a bit quicker. Regardless, all 3 models indicate cold air wrapping
in from the northwest and rain changing over to snow Thursday
night into Friday morning. Not going to get too overly excited
about this since there are several major weather features between
now and then that will have some say on the evolution of this
future system, but figured it was worth a mention since it could
produce a few inches for folks north of the low track.

Very cold air will follow in the wake if this storm system which
will bring sub-freezing temperatures across the entire Midwest
over the weekend. Should see overnight lows in the 20s Friday
morning, with a few teens across northern Minnesota. Temperatures
will moderate slightly heading into early next week, but all in
all below normal temperatures will round out the month of October
and should carry over into at least the first part of November.


.AVIATION...(For the 12Z TAFS through 12Z Tuesday morning)
Issued at 639 AM CDT Mon Oct 23 2017

VFR conditions today with breezy afternoon winds gusting to near
30 kts. A surge of cold air will move in overnight and could see
wind gusts near 40 kts along with some MVFR stratus. Light rain is
possible at KRNH and KEAU.

Not anticipating any issues with precipitation, but should have
strong winds at KMSP, especially later tonight when gusts near 40
mph are possible along with MVFR clouds. The winds should
gradually diminish on Tuesday.

Wed...VFR. Wind W 10-15 kts.
Thu...VFR with MVFR late. Wind SW 5-10kts bcmg NW at 20G30 kts.
Fri...VFR. Wind W at 15G25kt




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