249
FXUS63 KARX 172356
AFDARX

Area Forecast Discussion
National Weather Service La Crosse WI
556 PM CST Mon Nov 17 2025

.KEY MESSAGES...

- Measurable snow (potentially 1-4 inches) likely between
  Interstate 90 and 94 late tonight through Tuesday morning. A
  Winter Weather Advisory is in effect for portions of SE
  Minnesota and West Central Wisconsin from 1 AM through noon
  tomorrow.

- Rain later in the week (Thursday night and Friday) is looking
  far less likely, so transitioned the forecast drier.

&&

.DISCUSSION...
Issued at 206 PM CST Mon Nov 17 2025

Today - Tuesday: Rain/Snow Expected for Most

Bit of a messy forecast over the next 30 hours or so. A weak upper
low is ejecting out of the North Central Rockies with a surface low
taking shape to its south in the lee of the Colorado Rockies. These
are expected to trek east into the Mid/Upper Mississippi River
Valley over the next day or so.  As moisture transport begins to
resaturate the lower levels of the atmospheric profile across the
region, showers will start to move in from the southwest later this
afternoon and evening. This should start off as all rain before
things take a turn for the more complicated.

As we move into the 00-06Z timeframe, we`ll see a signficiant 850-
700mb fgen band move in and drape itself across the tri-state area.
Around this time, we should also see an increase in synoptic lift
from the left exit region of the upper jet which will be located
around the base of the upper low. As temperatures begin to cool and
wet bulb temperatures begin to approach freezing, we`ll start to see
a transition to a rain/snow mix. How long this transition takes is
still a point of contention among guidance. The favorable dynamics
may allow the transition to mostly snow happen faster than the
current late overnight timeframe. Unfortunately, with the 17.12Z
HREF soundings showing largely isothermal profiles through 750 mb
around 0 deg C, the slightest shift in temperature will impact what
is seen on the surface so near term updates in when and where the
transition happens will likely be needed. For now, have introduced
the rain snow mix after 06Z with snow becoming more dominant closer
to 12Z generally between the I-90 and I-94 corridor as latest hi-res
guidance has indicated a slight northward shift in the band of
snowfall. Snowfall rates look to peak around 0.5 in/hr with very low
(less than 10%) chance of seeing rates at or above 1 in/hr. Snow
ratios will be lower than normal around 6-8:1 so it will be a heavy,
wet, and slushy snow. This is also expected to fall overnight and
into tomorrow morning, likely impacting the morning commute. Totals
look to hover in the 1-4 inch range but this is highly dependent on
when the transition to mostly snow occurs. If it occurs earlier than
currently expected, these totals might be too low. If the transition
occurs later, or not at all, these totals will be too high. This is
a particularly finicky forecast with lots of emphasis placed on a
narrow range of temperatures that could easily fluctuate. Even this
close in time, details are subject to change so stay tuned for any
needed forecast updates.

As the low and subsequent fgen band slide to the east, precipitation
will quickly come to an end through the late morning and early
afternoon. With the potential for a light snowpack and continued
cloud cover across the region, temperatures will struggle to reach
the 40 degree mark tomorrow afternoon with most locations staying in
the mid to upper 30s.


Wednesday - The Weekend: Some Rain Chances, Near Normal Temps

The forecast gets a bit less hectic as we move into the mid to late
week timeframe. Wednesday should be dry with continued cool
temperatures in the upper 30s to mid 40s. A longwave trough is
expected to move across Canada by late in the week, dragging a
trailing cold front through the area Thursday. Temperatures will
have rebounded into the mid 40s to low 50s by then so precipitation
should stay as all rain.

Yet another upper low across Southern California is expected to
pivot northeast Thursday into Friday. Latest guidance has trended
this low further south than the past couple days which would keep
precipitation across our area to a minimum with only areas along and
south of I-90 seeing any sort of chance during the day on Friday.
Overall, chances for rain both days are limited to the 20-30% range.
A surface high moves in behind these systems to keep the forecast
dry for the weekend.  Temperatures should remain near normal in the
mid 40s to low 50s.

&&

.AVIATION /00Z TAFS THROUGH 00Z WEDNESDAY/...
Issued at 556 PM CST Mon Nov 17 2025

VFR conditions will quickly deteriorate to MVFR and eventually
IFR/LIFR tonight as rain and snow move into the region. At
onset, precipitation will begin as rain with low-VFR to MVFR
cigs and vsbys. However, as a changeover to snow occurs at some
locations closer to daybreak on Tuesday. As this changeover
occurs, IFR to LIFR reductions will ensue throughout much of the
morning hours with high probabilities (70-100% chance) in the
recent HREF for IFR cigs. Snow accumulations will predominantly
remain north of both KLSE and KRST, however cannot rule out some
slushy accumulations of an inch or two. Precipitation will then
exit by noon resulting in improving vsbys but lingering low-
level saturation shown in bufkit soundings would suggest IFR
cigs remaining through the afternoon on Tuesday. Winds will
generally remain around 5-10 kts from the east throughout the
TAF period.

&&

.ARX WATCHES/WARNINGS/ADVISORIES...
WI...Winter Weather Advisory from 1 AM to noon CST Tuesday for
     WIZ029-032>034-042>044.
MN...Winter Weather Advisory from 1 AM to noon CST Tuesday for
     MNZ079.
IA...None.

&&

$$

DISCUSSION...Barendse
AVIATION...Naylor