Area Forecast Discussion
Issued by NWS La Crosse, WI

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FXUS63 KARX 200003

Area Forecast Discussion
National Weather Service La Crosse WI
603 PM CST Mon Feb 19 2018

.UPDATE...This evening into the overnight
Issued at 600 PM CST Mon Feb 19 2018

Have issued an Dense Fog Advisory for Fayette, Clayton, and Grant
counties until 12Z Tuesday morning. Visibility was down to 0 at
Oelwein just before 6 PM.  The rest of the forecast is on track.


.SHORT TERM...(This evening through Tuesday)
Issued at 206 PM CST Mon Feb 19 2018

Watching two areas of heavier precipitation this afternoon. The
first is in the vicinity of a surface warm front across northeast
Iowa and far southern Wisconsin. With current temperatures in the
mid to upper 30s, this precipitation will fall as rain. The second
is mainly north of I-90 where temperatures are colder from the mid
20s to lower 30s. This precipitation is mainly freezing rain/
drizzle, but is at times mixing with some light snow and/or sleet.
Models are in good agreement, showing precipitation gradually
weakening from south to north through the rest of the afternoon
and into the evening as the depth of low-level saturation

This evening into the early overnight will generally be dry, but
could continue to see periods of light freezing drizzle for areas
where temperatures are below 32 degrees. Bigger concern will be a
second round of precipitation later tonight into Tuesday morning
as a short-wave rides along southwest aloft and across the forecast
area. 19.12Z model suite and latest RAP/HRRR are in agreement
showing that there may be some more convective clusters within
the broader precipitation field. More vigorous vertical motion and
deeper moisture within these clusters could promote a mix of snow
and sleet at times, but biggest threat is still freezing rain.
Ice accumulations are expected across a broader swath of the
forecast area tonight into Tuesday morning as surface temperatures
drop into the 20s to lower 30s for most areas.

Current forecast calls for an additional tenth to two tenths of
ice through Tuesday morning. So far today, the highest ice totals
have been across portions of southeast Minnesota, but are
generally a tenth of an inch or less. Will need to watch this
area in particular overnight for a potential short-lived upgrade
to an Ice Storm Warning, but lower confidence in placement of
higher amounts precludes issuance at this time. Most other areas
have seen little to no ice today, so current Winter Weather
Advisories look good with no changes planned in timing or area.
Keep in mind that any ice that has already fallen will not melt
through tomorrow with sub-freezing temperatures. Untreated roads,
sidewalks, and parking lots will continue to be slick. The Tuesday
morning commute will also be hazardous and slow-going for many
areas. Make sure to check the latest road conditions before
leaving for school or work.

One additional concern to watch tonight will be the potential for
dense fog across portions of northeast IA and southern WI. Current
visibility south of the warm front is poor in many places and this
could advect northward into Fayette, Clayton, and Grant Counties.
Will monitor through the night for possible fog headlines.

.LONG TERM...(Tuesday night through Monday)
Issued at 206 PM CST Mon Feb 19 2018

Not much time to delve into the long term forecast, but mid-week
looks dry with the next best chances for precipitation Thursday
night into Friday and Saturday night as a series of ill-resolved
short-waves move across the region. Precipitation type will be
dependent on temperatures, but right now, snow looks to be the
dominant type. Temperatures look to be cooler through mid-week
with a warming trend Friday into the weekend.


.AVIATION...(For the 00Z TAFS through 00Z Tuesday evening)
Issued at 603 PM CST Mon Feb 19 2018

IFR to LIFR conditions are expected in low stratus, fog, and
drizzle/freezing drizzle at times. This will continue through
around 14Z Tuesday morning then the drizzle/freezing drizzle
should be ending. There may also be some sleet showers moving
through the taf sites in the 09Z to 12Z Timeframe. After 14Z plan
on a very slow improvement to MVFR conditions by late Tuesday
afternoon into Tuesday evening.


WI...Winter Weather Advisory until 6 PM CST Tuesday for WIZ017-029-

     Winter Weather Advisory from 9 PM this evening to 6 PM CST
     Tuesday for WIZ053>055.

     Dense Fog Advisory until 6 AM CST Tuesday for WIZ061.

MN...Winter Weather Advisory until 6 PM CST Tuesday for MNZ079-

IA...Winter Weather Advisory until 6 PM CST Tuesday for IAZ008>010-

     Winter Weather Advisory from 9 PM this evening to 6 PM CST
     Tuesday for IAZ011-029-030.

     Dense Fog Advisory until 6 AM CST Tuesday for IAZ029-030.



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