Area Forecast Discussion
Issued by NWS Twin Cities, MN

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FXUS63 KMPX 220507

Area Forecast Discussion
National Weather Service Twin Cities/Chanhassen MN
1107 PM CST Wed Feb 21 2018

.SHORT TERM...(This evening through Thursday)
Issued at 307 PM CST Wed Feb 21 2018

Surface high pressure shifts east of the area this evening and
allows weak warm air advection to ensue ahead of the next
approaching shortwave. This scenario will make for increasing
clouds overnight, along with temperatures reaching their minimums
overnight, then remaining steady or increasing toward daybreak.

Hi-resolution models indicate we will most likely stay dry in our
forecast area until after daybreak, although the I-90 corridor
should see snow shortly thereafter. Snow will then expand north
and east across the area during the afternoon hours. By Thursday evening,
much of the Minnesota portion of the forecast area should have 1-2
inches of new snow on the ground. This will quite likely hinder
the evening commute, especially since snow will be ongoing during
it. Have therefore issued a Winter Weather Advisory for most of
the MN portion of the area into northwest WI. Southeast of the
Twin Cities metro area and across west central WI (including Eau
Claire), given the precipitation onset is later and there`s more
uncertainty regarding precipitation type, will hold off on an
Advisory for now.

.LONG TERM...(Thursday night through Wednesday)
Issued at 307 PM CST Wed Feb 21 2018

Thursday night snow will be ongoing, with freezing drizzle
possible from south central MN into west central WI. By the time
the snow ends, the Advisory area can expect 2-4 inches with
isolated totals nearing 5 inches in central MN. Nearly the entire
area could see some freezing drizzle overnight into Friday morning
as we lose saturation in the dendritic layer.

Friday is our break between systems as surface high pressure
builds in. Given the pattern aloft, however, this break will be
short-lived. By Saturday afternoon, the 21.12Z GFS and ECMWF
solutions are now in pretty good agreement that a surface low
circa 995mb will be located over Iowa, and deepening as it heads
toward the Great Lakes. This feature is accompanied by a
negatively tilted mid-level trough, and most models yielding
0.25-0.50 inches of QPF. That being said, if this set-up were to
come to fruition, it would be a winter storm warning-worthy event
for our forecast area. Plenty of time and potential for shifting
at this point, but given models are already beginning to hone in
on a track, it bears close watching.

Sunday through the middle of next week we dry out as ridging
dominates for a few days. This will also yield near-normal temps
mostly in the 30s.


.AVIATION...(For the 06Z TAFS through 06Z Thursday night)
Issued at 1107 PM CST Wed Feb 21 2018

Only change to thinking from the 00z TAF was to slow the arrival
of snow per trends from the HRRR. When main band gets here vis of
3/4sm to 1 1/2sm will be predominate vis, though some 1/2sm vis is
certainly possible, though that looks more like the exception as
opposed to the norm. Again, any sub-vfr cig restriction look to be
tied to having snow actively falling.

KMSP...HRRR continues to point to a later arrival of the snow,
with it now looking to arrive between 20z and 22z per the GFS and
NAM, with the heaviest snow still expected between 1z and 7z.
Still looks likely for 3-4 inches, with max rates of 3/4" per

Fri...MVFR cigs in mrng. VFR in aftn. Wind W 5-10 kts.
Sat...VFR in mrng. MVFR or lower with SN in the afternoon.
      Significant accums possible Sat night. Wind E 5-10 kts.
Sun...MVFR early, VFR late. Wind W 10-15 kts.


WI...Winter Weather Advisory from noon Thursday to 6 AM CST Friday
     for WIZ014>016-023.

MN...Winter Weather Advisory from noon Thursday to 6 AM CST Friday
     for MNZ041>045-047>053-055-057>063-066-068>070-076-077-084-

     Winter Weather Advisory from noon Thursday to midnight CST
     Thursday night for MNZ054-056-064-065-067-075.

     Winter Weather Advisory from 9 AM Thursday to midnight CST
     Thursday night for MNZ073-074-082-083-091-092.



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