630
FXUS63 KARX 121250
AFDARX

Area Forecast Discussion
National Weather Service La Crosse WI
650 AM CST Wed Feb 12 2025

.KEY MESSAGES...

- Snow spreads northeast through the area this morning. Highest
  amounts of 5 to 7 inches are expected in far southwest
  Wisconsin and adjacent portions of northeast Iowa. A sharp
  cutoff in accumulations is expected to the north near the
  Interstate 90 corridor, further decreasing to near 1" in parts
  of west-central Wisconsin.

- Very cold conditions are expected tonight, with wind chills of
  25 below zero expected west of the Mississippi River Valley,
  where a Cold Weather Advisory is in effect.

- Another couple rounds of snow are likely Friday afternoon
  into Saturday. There may be the need for additional Winter
  Weather Advisories.

- Additional nights with very cold wind chills are possible
  Sunday night through Tuesday night.

&&

.DISCUSSION...
Issued at 327 AM CST Wed Feb 12 2025

Today and Tonight

Snow is continuing to spread slowly north across northeast Iowa
and southwest Wisconsin early this morning. This snow should
spread northward into the Interstate 90 corridor between 6 AM
and 8 AM and across the remainder of the area late this morning
and early afternoon. With the CAMS and operational model runs
having some higher QPF in the Interstate 90 corridor and BUFKIT
soundings suggesting a potential that 200 to 300 mb of the
sounding could be located in the dendritic growth zone, opted to
add a Mitchell County in northeast Iowa, Fillmore, Houston, and
Mower Counties in southeast Minnesota, and La Crosse County in
west central Wisconsin to the Winter Weather Advisory. With that
said, there is still some concern that the dry air associated
with the cold air conveyor belt could result in a sharp cutoff
in the snow either along or north of the Interstate 90 corridor.
Like yesterday, we currently have 2 to 5 inches in the Winter
Weather Advisory and 5 to 7 inches in the Winter Storm Warning.

The combination of clearing skies and freshly fallen snow will allow
for good radiative cooling tonight. This will allow temperatures to
fall into the single digits above and below zero. With a northwest
wind of 10 to 15 mph, wind chills will range from 15 to 30 below.
The coldest wind chills (25 to 30 below) will be found along and
west of Highway 52 in northeast Iowa and southwest Wisconsin. Due to
these wind chills, a Cold Weather Advisory was issued from midnight
tonight through 9 AM Thursday for out 8 counties in the western part
of our County Warning Area.

Friday and Friday Night, the 12.00z models are in very good
agreement that a shortwave trough will move east through the
forecast area. While the models are in good agreement that it will
snow, there is still some concern that very dry air ahead of this
system will reduce precipitation and snow amounts some. The
12.00z NBM continues to have very large spreads in its 24-hour
QMD precipitation. For example for both La Crosse and Rochester,
the 10th percentile is a couple of hundreths and the 90th
percentile range from 0.6 to 0.7 inches. With the 25th to 75th
percentile have snow totals ranging from 1 to 5 inches in
northeast Iowa and southeast Minnesota and 3 to 7 inches in
southwest and central Wisconsin. If the models continue to
produce this much snow, a Winter Weather Advisory may be needed
for much of the area.

Saturday and Saturday night

While many of the ensemble members have the Arctic cold front
well south and southeast of the area, there are now some
ensemble members including the operational ECMWF which slow down
the front enough that we could see the potential for snow. With
snow to liquid ratios around 20 to 1, there will be the
potential for yet another Winter Weather Advisory south of
Interstate 90.

Sunday-Wednesday nights

It continues to look like it will be very cold each night with low
temperatures ranging from 10 to 20 below. Wind chills nightly look
to range from 15 to 30 below. There will be potential for Cold
Weather Advisories. On Sunday and Wednesday nights, it looks like
they would be mainly west of Mississippi River and area-wide on
Monday and Tuesday nights.

&&

.AVIATION /12Z TAFS THROUGH 12Z THURSDAY/...
Issued at 548 AM CST Wed Feb 12 2025

Incoming snowfall can be seen on surface observations moving
through central Iowa at 12.12Z TAF issuance, as far north as
KCCY. Accompanying visibility reductions are MVFR, decreasing
near IFR farther southwest into north-central Iowa. The
northwestern periphery of snowfall is oriented southwest to
northeast near KRST. The main axis of snowfall can be seen
bearing down on KLSE.

Expect snowfall to spread northeast through the morning hours,
becoming more widespread by the early afternoon. Large flakes
and high snowfall rates will quickly reduce visibilities to IFR
to potentially LIFR. Have introduced TEMPO LIFR visibilities
in the KLSE TAF this afternoon as a result. Question is how
widespread and northwest the highest impacts, i.e., lowest
visibilities, will reach. Limited impacts expected along our
northern periphery counties in central Wisconsin (e.g., KMDZ).
Snowfall and accompanying impacts expected to shift east
overnight into central Wisconsin.

&&

.ARX WATCHES/WARNINGS/ADVISORIES...
WI...Winter Weather Advisory until 3 AM CST Thursday for WIZ041>044-
     053>055.
     Winter Storm Warning until 3 AM CST Thursday for WIZ061.
MN...Winter Weather Advisory until 3 AM CST Thursday for MNZ094>096.
     Cold Weather Advisory from midnight tonight to 9 AM CST
     Thursday for MNZ086-087-094-095.
IA...Winter Weather Advisory until 3 AM CST Thursday for IAZ008>011-
     018-019-029.
     Cold Weather Advisory from midnight tonight to 9 AM CST
     Thursday for IAZ008-009-018-019.
     Winter Storm Warning until 3 AM CST Thursday for IAZ030.

&&

$$

DISCUSSION...Boyne
AVIATION...JAR