Area Forecast Discussion
Issued by NWS Twin Cities, MN

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FXUS63 KMPX 111154

Area Forecast Discussion
National Weather Service Twin Cities/Chanhassen MN
554 AM CST Thu Jan 11 2018

.UPDATE...For 12z Aviation discussion below


.SHORT TERM...(Today and tonight)
Issued at 359 AM CST Thu Jan 11 2018

Temperatures are plummeting in the wake of the cold front. Areas
of drizzle will continue to transition to freezing drizzle and/or
snow. In the meantime, untreated roads/pavement will likely
"flash freeze" given the residual moisture from earlier
precipitation, as is being observed along I-35 near Albert Lea.
Therefore even though anticipated snowfall totals in most areas
alone would not justify continuance of the winter weather
advisory, the impacts from the freezing do warrant it. Have moved
up the ending time for MN counties to 18z given blowing snow
concerns will be less given notably lower accums. The highest
snowfall accumulations in the deformation band still look to just
barely clip the eastern fringes of the forecast area, with 4-5
inch amounts the maximum. Have therefore downgraded the warning to
an advisory.

Temperatures will either remain steady (west central MN) or fall
through the day (elsewhere). In the wake of the snow, most areas
will see single-digit temperatures by late afternoon, likely even
below zero in west central MN (near Alexandria). While northwest
winds do look to lose their gusts during the evening, they should
stay in the 5-7 knot range overnight. These winds combined with
temps falling into the single digits to teens below zero will make
for very cold wind chill values tonight. Areas generally west of
Interstate 35 look to see wind chills falling into Advisory
criteria range, so anticipate headlines will likely be needed
later today.

.LONG TERM...(Friday through Wednesday)
Issued at 359 AM CST Thu Jan 11 2018

The long range period will be dominated by arctic air through
Tuesday, before we start working our way out of it. The northwest
flow bringing the arctic air will send a couple of clippers Friday
and again Sunday.

Starting with temperatures, the lack of snow we are getting out of
the system moving through now will definitely limit the punch of
this arctic out break, especially with overnight lows. Even then
though, 925-850mb temps will not be as cold as what we saw at the
beginning of the month, so sub-zero highs will be fairly uncommon.
We will get a brief warmup on Sunday with WAA ahead of the
clipper, but outside of that, we`ll see highs around 20 degrees
below normal Fri, Sat, Mon, and Tue. For lows, to see -10F or
colder, you`ll need snow, so central MN and west central WI will be
the only places that see those kinds of lows. Of course with arctic
air comes wind chill headlines. Any wind chill headlines needed for
tonight will need to be continued through Friday morning. Friday
night will be another wind chill headline worthy night before high
pressure moving in Saturday allows the winds to drop off. WAA ahead
of the clipper on Sunday will give us a break from wind chill
headlines Saturday night and Sunday. Behind the clipper though, we
will likely see wind chills drop to -20 to -35 once again, so wind
chill headlines will likely be needed again Sunday night through
Tuesday night.

For snow chances, models continue to push the clipper for Friday
farther southwest and this now looks to stay southwest of MN. Sunday
will see a potent shortwave deepening as it drops down from Canada
and looks to be a bit more giving in the snowfall department. This
looks like your standard clipper, with a pretty broad 1-3" of snow
falling. Soundings show the DGZ extending from the surface to nearly
10k feet, so we should see some healthy snow ratios with this snow,
likely in excess of 20:1.

For the end of the period, we will be on a warming trend. In fact,
by the end of the next week, it is looking like we could see more
highs above the freezing mark. As we saw recently, the one advantage
to having little snow cover is we can warm up quickly.


.AVIATION...(For the 12Z TAFS through 12Z Friday morning)
Issued at 555 AM CST Thu Jan 11 2018

Temperatures have plummeted into the single digits and winds have
shifted to the northwest and become quite gusty behind a cold
frontal passage. Light to moderate precipitation in the form of
rain and freezing drizzle will continue changing over to snow
during the first few hours of the TAF period in the wake of the
front. IFR conditions will improve to low-end MVFR during the
afternoon, then VFR Thursday evening. Northwest winds
15-20G25-35 knots will decrease to around or below 10 knots
Thursday evening.

The precip type from here on out should be snow. High confidence
in ceilings below 1700 feet through at least mid afternoon. Cigs
look to clear out Thursday evening.

Fri night...VFR. Wind NNW 5-7kts.
Sat...VFR. Wind NW 5 kts.
Sun...MVFR with -SN likely. Wind S 5-10 kts. Mon...VFR. Wind NW 10


WI...Winter Weather Advisory until 6 PM CST this evening for

MN...Winter Weather Advisory until noon CST today for MNZ041>045-

     Winter Weather Advisory until 6 PM CST this evening for MNZ078-



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