Area Forecast Discussion
Issued by NWS Twin Cities, MN

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FXUS63 KMPX 162358 AAA

Area Forecast Discussion...UPDATED
National Weather Service Twin Cities/Chanhassen MN
558 PM CST Fri Nov 16 2018

.SHORT TERM...(This evening through Saturday)
Issued at 220 PM CST Fri Nov 16 2018

Surface analysis this afternoon shows a clipper low pressure center
over the central CD/NE border with Canadian high pressure centered
over western Alberta province but nudging into the Northern Plains.
Aloft, a large upper level low persist over Hudson Bay with a broad
longwave trough encompassing much of eastern-central NOAM. Several
shortwave trough axes are rounding the western and southern
peripheries of the upper low, of which the one currently dropping
through the Dakotas and into the Central Plains tonight will be the
main player to interact with the aforementioned surface low. The
trough axis will remain positively-oriented, generally ENE-WSW, as
it drops through the Upper Mississippi River Valley late tonight.
Moisture is fairly compact and limited to near proximity of the
upper trough and surface low, and within fairly progressive flow
thru the upper levels. This would in essence limit duration of
snowfall, plus the track of the surface low would also keep best
accumulations south of I-94, even to the limit where northern
fringes of the WFO MPX coverage area may see little to no
accumulations. However, enhanced FGEN along and south/east of the
surface track, which is aligned with the entrance region of an
arriving jet streak aloft, may help enhance snowfall amounts just a
bit. So, for the latest forecast depictions, we`ve gone more along
what multiple HI-RES models have indicated which is lesser
QPF/snowfall north of I-94 then a tighter gradient south of I-94 to
the IA border. In that area, which is where the Winter Wx Advy
continues, there will be 3-5" accumulations with less than 3" to the
north. Timing is still generally on track with -SN already being
reported in western MN, translating to eastern MN (including the TC
metro) around 23z, then continuing into western WI. The heaviest
snowfall looks to occur 01z-05z, then gradually diminishing such
that only flurries looks to be left over by 09z-12z on into late
Saturday morning.

In addition to the snowfall from the passing surface low, a
tightened pressure gradient will follow the low on its way off to
the south and east, keeping breezy/gusty conditions in place
overnight through tomorrow. These winds will produce 2 results:
some blowing/drifting snow (mainly for western MN) and wind chills
down into the single digits overnight through Saturday morning.
Conditions will steadily improve during the day on Saturday but
temperatures will remain cold. Lows tonight will drop to the 10-
20 deg F range while highs Saturday will only reach 15-25 deg F.

.LONG TERM...(Saturday night through Friday)
Issued at 220 PM CST Fri Nov 16 2018

Deep troughing aloft becomes established over the weekend with well-
below normal temperatures expected to continue into Tuesday. A
couple weak clippers will skim across the area Monday & Tuesday as
jetstreaks embedded in the flow aloft provide a few periods of
widespread ascent aloft. Little moisture will be present given the
Arctic airmass in place however so only a few hundredths of an inch
of precipitation are expected. Only looking at a dusting of snow
with these systems across central Minnesota and northwest Wisconsin,
but it would not surprise me for both waves to come through dry with
little more than an increase in cloud cover.

The deep trough moves off to the east midweek as strong ridging
builds over the central US, with the jet being pushed all the way up
over Hudson Bay. The Euro is stronger with the ridge and as a result
is warmer, with 850 mb temperatures above 12 C Thanksgiving day over
western Minnesota compared to 8-10 C with the GFS. Despite the warm
temperatures aloft, surface temperatures will be dependent on the
extent of existing snow cover from tonight`s system as well as the
amount of cloud cover with predominately southeast winds. Currently
expecting highs to be in the 40s Wednesday and Thursday, with the
potential for some areas to get into the upper 40s on Thanksgiving
if we see plenty of sunshine.

The ridge breaks down to end the week as another wave approaching
Friday. What kind of temperatures/precipitation possible will depend
on where this wave spins up a low, but Friday into Saturday looks
like our most organized shot at precipitation for next week.


.AVIATION...(For the 00Z TAFS through 00Z Saturday evening)
Issued at 558 PM CST Fri Nov 16 2018

Snow will remain south of I-94 tonight, with LIFR conditions at
RWF and MKT. It appears AXN, STC, RNH, and EAU will be dry and
VFR, with perhaps scattered cigs near 2kft. The snow will exit to
the southeast between 05-08Z, with clear skies expected Saturday.

KMSP...Should remain on the northern edge of the snow with MVFR
visibilities and cigs likely for most of the evening. Could see
brief IFR vsbys early this evening. Accumulations of an inch or
less expected.

Sun...VFR. Winds SW 10 kts.
Mon...Mainly VFR. MVFR ceilings possible. Winds NNW 5-10 kts.
Tue...VFR. Winds NE 5 kts becoming S.


MN...Winter Weather Advisory until 6 AM CST Saturday for MNZ068>070-

     Winter Weather Advisory until 4 AM CST Saturday for MNZ047-048-



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