Area Forecast Discussion
Issued by NWS Twin Cities, MN

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FXUS63 KMPX 202007

Area Forecast Discussion
National Weather Service Twin Cities/Chanhassen MN
207 PM CST Mon Nov 20 2017

.SHORT TERM...(This evening through Tuesday)
Issued at 207 PM CST Mon Nov 20 2017

Surface analysis this afternoon shows a surface low over far
southern Manitoba province with a warm front extending SE through
northern MN into northwest WI and a cold front dropping into
northwest ND and eastern MT. Extensive high pressure resides over
much of the eastern and southern CONUS. Aloft, a modest trough
axis is shifting east over south-central Canada through the
Mississippi River Valley with ridging over the southeastern CONUS
and over the western states. As the trough aloft drives southeast,
this will also drag the Canadian surface low with it through the
northern Great Lakes. The cold front of this system will push
through MN/WI late this evening into the early morning hours. The
trough will become more pronounced overnight as a cutoff low forms
within it, helping enhance subsidence on the backside within
strong northwest flow. Surface high pressure will nose into the
northern Plains and upper Mississippi River overnight behind the
front, creating a strong surface pressure gradient by daybreak. In
addition, fairly deep mixing around sunrise through the first
half of the day will allow for 40-50kt low level winds to mix down
near the surface, especially in western and southern MN. As such,
sustained winds will likely hit the 25kt mark for several hours
in the morning so have opted to issue a Wind Advisory for much of
western and southern MN for the morning and early afternoon hours.
As for cloud cover, extensive high clouds will linger through
this evening then some breaks will develop going into the early
morning hours. This will end up being short-lived as mid-level
decks will move into the area with the frontal passage. After
daybreak, these clouds will also scatter out, resulting in a mix
of sun and clouds by the afternoon. The other noticeable change
will be the strong cold air advection associated with the cold
front. Highs tomorrow will be 20-25 degrees cooler than the
temperatures experienced this afternoon, with lows tonight ranging
from the upper teens to the mid 20s.

.LONG TERM...(Tuesday night through Monday)
Issued at 207 PM CST Mon Nov 20 2017

A fairly nondescript extended portion of the forecast can be
expected through the Thanksgiving holiday weekend.

The aforementioned cold high pressure airmass will remain in place
through Wednesday then be shoved off to the east by another
frontal system. A weak cold front will push through, bringing a
meager reinforcing shot of colder air but also the potential for a
few snow showers over mainly central portions of MN Wednesday
afternoon. Nothing significant is expected from this frontal
passage. High pressure will then regain control Wednesday night
through Friday, with another surge of temperatures expected for
Friday as the area once again sees a warm frontal passage and deep
southwest flow. Highs will again climb to the 40s and 50s but
this will again be short-lived as a potent cold front is expected
to push through the area Friday night into Saturday morning. Ahead
of this front, a wintry mix of precipitation over western and
central MN Friday morning will transition to all rain by Friday
afternoon for much of central MN into western WI. Then another
strong bout of CAA will take place Friday night through the
weekend, again dropping highs roughly 20-25 degrees from Friday to
Saturday. High pressure will then regain control over the weekend
into the start of next week, making for dry and seasonably cool


.AVIATION...(For the 18Z TAFS through 18Z Tuesday afternoon)
Issued at 1050 AM CST Mon Nov 20 2017

VFR conditions expected through this TAF period. High ceilings
will dissipate later this evening but then mid-level ceilings will
approach close to daybreak with the arrival of a cold front. The
duration of mid-level ceilings will be relatively short, roughly
4-6 hours, then high scattered clouds will remain for the rest of
the day tomorrow. Strong NW winds will develop with the frontal
passage and remain in place for much of the day tomorrow with
gusts as high as 35 knots.

KMSP...Only concern will be strong NW winds which will likely
occur during the Tuesday morning push. Ceilings could drop as low
as 4 kft but not expecting anything into MVFR or lower range.

Wed...VFR. Winds SW 5-10 kts.
Thu...VFR. Winds NW 5 kts.
Fri...Mainly VFR. Chance p.m. MVFR/-SHRA. Winds SW 10 kts.


MN...Wind Advisory from 6 AM to 2 PM CST Tuesday for MNZ041-047-048-



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