Area Forecast Discussion
Issued by NWS Twin Cities, MN

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608
FXUS63 KMPX 140015
AFDMPX

Area Forecast Discussion
National Weather Service Twin Cities/Chanhassen MN
615 PM CST Wed Dec 13 2017

.UPDATE...
Issued at 543 PM CST Wed Dec 13 2017

Updated to include 00z aviation discussion below.

&&

.SHORT TERM...(This evening through Thursday)
Issued at 253 PM CST Wed Dec 13 2017

The clipper system that brought us a quick shot of snow this
morning continues to race southeast and as of this writing the
surface low had already reached Chicago. Northwest winds have
continued to be strong through the day, especially in western MN.
The pressure gradient will weaken markedly this evening though,
and the atmosphere will decouple a few hours after dark which will
further allow the winds to weaken at the surface. Some spots in
western and southern MN have seen the winds decrease below Wind
Advisory criteria, so went ahead and removed the wind advisory for
several counties. The strong winds will continue through the
afternoon for a portion of the Minnesota River Valley from Redwood
Fall through Mankato and southward to the Iowa border. The winds
in this area will decrease substantially after 6pm.

Otherwise, the low clouds are expected to stick around and bring
the chance for light snow showers or flurries through the day
tomorrow under deep cyclonic flow. Most of the precip will stay to
our west as a shortwave dives south through the Dakotas.

.LONG TERM...(Thursday night through Wednesday)
Issued at 253 PM CST Wed Dec 13 2017

The main focus of the long term is this weekend.  But first, a
clipper system will drop south through Minnesota Friday, but
remain along and north of I-94, producing the bulk of its precip
north of there.

The ECMWF and the GFS both indicate a deep trough extending into
northern Mexico by early Friday, with the actual shortwave mostly
holding firm through Saturday. Another system moves onshore from
the west and it will be interesting to see how these two interact.
The GFS moves the northern Mexico system quickly east through the
Ohio River Valley and still shears out the other system, and
doesnt produce any exciting weather for us. The ECMWF has a
somewhat similar response but doesn`t shear the western system so
quickly and for the second consecutive run of the model, it
produces a stripe of light qpf across southern MN and western WI
late Saturday night into Sunday. Hence, slight chance pops are in
place to account for this potential and this will be something to
watch.

A strong system moving across Canada will pull warm air northward
Monday, and hence the forecast for highs in the 35-40 degree
range. A dry cold front will pass through eventually, but not
before both Monday and Tuesday finish above normal.

&&

.AVIATION...(For the 00Z TAFS through 00Z Thursday evening)
Issued at 543 PM CST Wed Dec 13 2017

Backdoor cold front continues to drift SSW across the area, with
MVFR ceilings in close proximity to the front and some splotchy
VFR from NE MN making its way S. Overall, will look for all sites
to go MVFR through the overnight period and much of tomorrow with
VFR ceilings likely to develop late tomorrow afternoon. Gusty NW
winds will diminish to the 5-10 kt range a few hours into the
14/00z TAFs then remain in the 5-10kt range through tomorrow while
still from the NW.

KMSP...MVFR ceilings to prevail throughout tonight and tomorrow
with VFR ceilings likely to hold off until late tomorrow afternoon
or tomorrow evening. No precipitation expected and no visibility
restrictions expected.

/OUTLOOK FOR KMSP/
Fri...Chc MVFR. Wind WSW 5-10 kts.
Sat...Chc MVFR. Wind SW 5-10 kts.
Sun...Chc MVFR. Wind NW 5-10 kts.

&&

.MPX WATCHES/WARNINGS/ADVISORIES...
WI...None.
MN...None.
&&

$$

UPDATE...JPC
SHORT TERM...SPD
LONG TERM...SPD
AVIATION...JPC



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