FXUS63 KMPX 230521 AAC

Area Forecast Discussion...UPDATED
National Weather Service Twin Cities/Chanhassen MN
1121 PM CST Tue Jan 22 2019

Issued at 902 PM CST Tue Jan 22 2019

Hoisted a Winter Storm Watch for possible blizzard conditions
across western and southern Minnesota Wednesday night through
Thursday morning. Winds are expected to gust to 40 to 45 mph
behind an arctic front late Wednesday night and gradually subside
Thursday morning. The recent heavy snowfall across southern MN is
of particular concern and these areas will have the best chance
for whiteout conditions. Despite some light freezing drizzle this
morning, once the thin layer of crust is removed there will be
access to several inches of snow. Blowing snow potential is a
little more iffy over sections of west central MN where recent
snow has been less impressive, but the older snowpack as a whole
should still be capable. There are some uncertainties that won't
be worked out until the event unfolds, but given the potential, a
Winter Storm Watch seems necessary.


.SHORT TERM...(This evening through Wednesday night)
Issued at 300 PM CST Tue Jan 22 2019

Main concern in the near term is remaining light snow associated
with upper trough and incoming arctic cold front Wednesday night.

Upper trough shearing more to the east/northeast this evening.
Will likely continue the light snow/flurries to the east into the
evening. Only real threat of the upper trough to the south affecting
our area is to the far southeast. At this time it could still
clip our far southeast overnight. Not more than a chance at this
time. Flurry threat may continue a little longer over east central
MN as the trough exits.

Surface ridge builds east Wednesday with lighter winds becoming
southwest ahead of the incoming arctic front. The front moves in
Wednesday evening with the threat of show showers/flurries. We
introduced a lower end chance PoP for this possibility for now.
Not expecting anything significant accumulation wise. Northwest
winds with the fropa are the main concern along with the blowing
snow threat. Looking at Bufkit profiles, we are seeing an
increase in gust potential at least around 40 kts in a few
location over far west central Minnesota. This should continue a
few hours with initial fropa. Currently uncertain how much fresh
snow that location received last two days. Heavier accumulations
were seen farther northwest toward Alexandria. We will continue to
highlight the blowing snow/ground blizzard potential that period
and monitor tonights wind trends in the models.

.LONG TERM...(Thursday through Tuesday)
Issued at 300 PM CST Tue Jan 22 2019

Main concerns in the long term period continue to be the arctic
air and frigid wind chills through the weekend, along with
potential accumulating snow from a clipper early next week.

FROPA should be mostly through Minnesota/west-central Wisconsin by
Thursday morning, with a short 3-4 hour burst of the gustiest
winds associated with the greatest pressure rises immediately
behind the front. Intense low-level cold advection associated
with these pressure rises will result in steep lapse rates up to
900 mb, which would allow for gusts of 40 kts to reach the
surface. This window of highest gusts looks to be during the
overnight hours and before the morning commute, when impacts
should be at their lowest. Expect winds to diminish somewhat
during the morning and afternoon as the depth of mixing decreases,
but gusts around 30 kts still look possible during the afternoon.
As mentioned above it is uncertain how much blowing snow and
visibility concerns we will see, given that much of the area
missed out on any appreciable snowfall today. For now, it looks
like we'll fall just short of blizzard conditions during the
daytime hours.

Our coldest air of the season moves in behind the front, which
along with the aforementioned winds, will lead to frigid wind
chills Thursday and Friday morning. While certainly the coldest
air we've seen in some time, ensemble guidance suggests we're only
in the ~2 standard deviations below normal range for temperatures.
Temperatures will warm a few degrees with sunshine during the day
Friday but sustained winds of 15-20 mph during the day will allow
wind chills to drop to -25 to -30 across central and western
Minnesota. Temperatures really look to bottom out Friday morning
with the high pressure centered overhead, with lows around
-20 expected across central Minnesota. How low wind chills drop
Friday morning will be tricky as winds diminish through the night
with the decreasing pressure gradient. There could be a brief
period where wind chills could drop below -35 late Thursday
night before winds really drop off towards sunrise, but otherwise
winds look be too light during the early morning hours to really
hit wind chill warning criteria. The wind forecast should
hopefully become more clear as we get into the range of more
high- resolution guidance.

And last but not least, models are in fairly good agreement with
bringing a shortwave/clipper through the region during the Sunday
night/Monday timeframe. While we still can't pinpoint the path and
timing of this system just yet, the chance for accumulating snow
looks likely along its track.


.AVIATION...(For the 06Z TAFS through 06Z Wednesday night)
Issued at 1121 PM CST Tue Jan 22 2019

Band of VFR stratus is slowly lowering and there have been some
MVFR cigs on the back end of it over western MN. Following the
clearing of this band, areas of fog and LIFR cigs have developed
northwest of AXN, which should build southeast overnight.

KMSP...Stratus will move back in about 07Z, but should remain VFR
for much of the night.

THU...VFR with MVFR-IFR and -SHSN possible. Wind NW at 20G30kt.
FRI...VFR. Wind NW 5-10 kts.
SAT...VFR. Wind W 5-10 kts.


MN...Winter Storm Watch from late Wednesday night through Thursday
morning for MNZ065-067-073>077-082>085-091>093.

Winter Storm Watch from Wednesday evening through Thursday
morning for MNZ041-047-048-054>056-064.



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