Area Forecast Discussion
Issued by NWS La Crosse, WI

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FXUS63 KARX 102347

Area Forecast Discussion
National Weather Service La Crosse WI
547 PM CST Wed Jan 10 2018

.SHORT TERM...(Tonight through Thursday)
Issued at 320 PM CST Wed Jan 10 2018

Winter storm for the region with accumulating snows, blowing and
drifting, and the potential for a brief period of wintry mix - some

Drizzle and fog will spread across the local area tonight. Fog could
become locally dense at times before a warm front moves in from the
south and/or a cold front sweeps in from the west. Some potential
for a few hours of Dense Fog Adv. Will monitor.

The precipitation will quickly transition to snow, but about a 1-3
hour wintry mix period is possible. During the transition, the cold
air could lead to a "flash freeze" of standing water on untreated
roads and sidewalks. Unexpected slippery travel conditions could
result ahead of the main snow band.

As of the snow, latest model runs have shifted where the narrow band
is favored - currently now running mostly from central IA, through
southeast MN, and across northwest WI. Ratios from 10:14 to 1 with
qpf upwards of 1/2" would lay down 4 to 6 inches in the narrow band.

Meanwhile, tight pressure gradient will result in northwest wind
gusts upward of 35 mph in open and unsheltered areas, blowing and
drifting what snow falls. Southeast MN and northeast IA will have
the higher impacts.

With all this in mind, have issued Winter Storm Warnings and
Advisories based on anticipated impacts from the snow, icing threat,
and blowing/drifting concerns. Amounts may not reach warning
criteria, but the results will be impactful given the entire

All said, still not 100% certain in where this narrow band sets up
and there could still be some adjustments on where, and how much.

.LONG TERM...(Thursday night through Wednesday)
Issued at 320 PM CST Wed Jan 10 2018

Cold air returns for the upcoming weekend, post the departing cold
front/storm system, and looks to hang around for the early part of
the new work week. Single digit highs above and lows in the single
digits to teens below zero will be common. See the potential for
another round of Wind Chill Advisories for the night time/early
morning hours during this period - mostly in the favored wind areas
of southeast MN/northeast IA.

The GFS and EC are in pretty good agreement with dropping an upper
level shortwave trough out of northern Canada and across the Great
Lakes Sun afternoon/night. Pretty good slug of QG convergence
through the layers along with a slug of low level warm air
advection. Plenty of saturation to work with - per RH fields and
bufkit soundings. If scenario bares out, should see a prolonged
period of snow with a few inches of accumulation possible. Has a
Winter Weather Adv potential.


.AVIATION...(For the 00Z TAFS through 00Z Thursday evening)
Issued at 547 PM CST Wed Jan 10 2018

IFR to LIFR conditions are expected at the TAF sites this evening
and through much of the day on Thursday. Areas of fog, dense at
times, drizzle, and low stratus, will continue to impact the TAF
site during the overnight hours. The worst conditions will be at
KRST where the visibility is expected to fall to around 1/4 mile
at times. Look for rain to develop after midnight with a switch
over to snow at KRST by 13Z and around 14Z at KLSE. The snow will
be heavy at times at KRST with visibilities reduced to around 1/2
mile in snow and possibly some blowing snow as northwest winds
increase. Conditions look to improve to MVFR by late Thursday


WI...Winter Weather Advisory from 3 AM to 6 PM CST Thursday for

     Winter Storm Warning from 3 AM to 6 PM CST Thursday for WIZ017-

     Dense Fog Advisory until 10 PM CST this evening for WIZ061.

MN...Winter Weather Advisory from 3 AM to 6 PM CST Thursday for

     Winter Storm Warning from 3 AM to 6 PM CST Thursday for MNZ079-

IA...Winter Weather Advisory from 3 AM to 6 PM CST Thursday for

     Winter Storm Warning from 3 AM to 6 PM CST Thursday for IAZ008.

     Dense Fog Advisory until 10 PM CST this evening for IAZ029-030.



LONG TERM....Rieck
AVIATION...Wetenkamp is the U.S. government's official web portal to all federal, state and local government web resources and services.