945
FXUS63 KARX 081913
AFDARX

Area Forecast Discussion
National Weather Service La Crosse WI
213 PM CDT Sun Mar 8 2026

.KEY MESSAGES...

- Widespread precipitation chances return to the local area
  Tuesday evening, lasting through Wednesday mid-day. Initial
  rainfall switches to snow overnight Tuesday through Wednesday
  morning.

- Thursday night into Friday brings another chance for precip
  primarily east of the Mississippi.

&&

.DISCUSSION...
Issued at 206 PM CDT Sun Mar 8 2026

Precipitation Chances Return Tuesday & Wednesday

Benign conditions will prevail for the start of the work week
as upper level flow becomes more zonal in nature by 00z Monday.
This won`t last for long however as a closed, cutoff low,
currently sitting just off the coast of the Baja California
peninsula, starts to slowly slide east into the Southern
Rockies late Monday into Tuesday. Around the same time, a
shortwave trough will work its way across the Northern CONUS,
deepening as it reaches the upper Midwest by Wednesday. How
these two systems will phase together will play a significant
role in our forecast. Both the NBM 08.13z and 08.00z LREF Grand
Ensemble (EC, GEFS, Canadian) are showing a 75-95% chance of
measurable precipitation across the area but there remains
significant differences in the ensembles as to amounts and to a
lesser degree precipitation types. These significant differences
stem from how the ensemble member is handling the phasing of
the upper level systems. The EC members are lagging the phasing
until much later on Wednesday with the GFS comparably much more
aggressive with how quickly they phase together. With the EC
keeping the systems unphased for longer, we really only see the
influence of the northern stream shortwave and it`s much weaker.
The GFS ensemble members tend to highlight a much stronger
northern shortwave as it moves into our area with the southern
stream trough more completely in sync. As such, the GFS ensemble
members have higher precipitation amounts, especially in
regards to snow Tuesday night into Wednesday. The GEFS is
highlighting 20-40% probabilities for 3+ inches of snow, mainly
east of the river across West Central Wisconsin with the EC much
less enthused at less than 10% probabilities of 3+ inches of
snow across our area, keeping the higher probabilities well to
our north. Both are showing precipitation starting as rain late
Tuesday with a gradual transition to rain/snow mix as colder air
starts to work its way in behind the cold front. Eventually,
much of the area should see a complete transition to snow. The
main differences between the models in regards to precipitation
types are in how quickly this transition to all snow happens
with the GEFS being faster and the EC a tad slower. Given that
the evolution of the upper level pattern will play a key role in
how our forecast pans out, hopefully more clarity will be
gained once these systems are able to be more accurately sampled
as they start to move onshore later tomorrow.

Regardless of how the systems phase, the southern stream
shortwave is expected to eject out of the Rockies and into the
Plains. Out ahead of it, a weak surface low will start to take
shape and allow for more abundant deep moisture to work its way
into the Mid Mississippi River Valley late Tuesday into
Wednesday. With increased lift from the surface low and
divergence aloft ahead of the shortwave, a significant swatch of
showers and thunderstorms will likely form across the Central
US. Fortunately, we should largely stay clear of any severe
threat as by the time ample instability is realized, much of the
area should be behind the cold front. This will need to be
monitored closely over the next couple days as changes in timing
could increase the risk for thunderstorms. Currently, the Day 3
Marginal Risk area just clips Grant County with the higher risk
areas to our south and east.

Unsettled Pattern Continues Late Week

We`ll see a brief break in precipitation Wednesday night into
Thursday before chances for precipitation return yet again with
northwest flow becoming the prevailing pattern across the
region. With this pattern, weak shortwave troughs and clipper
systems are more likely to trek across the region. One of
interest looks to come right on the heels of the mid week
systems late Thursday into Friday as PoPs are already in the
50-70% range. Precipitation type is likely to start as a cold
rain with temperatures in the 40s and strong warm southerly flow
into the region. Some locations could see a rain/snow mix where
temperatures are allowed to cool more readily (North Central
Wisconsin) but these details remain fluid and subject to change.
Looking towards the weekend, more clipper systems/shortwaves
look possible but these are much less resolved and look weaker
overall.

&&

.AVIATION /18Z TAFS THROUGH 18Z MONDAY/...
Issued at 1207 PM CDT Sun Mar 8 2026

VFR conditions expected at the terminals for the next 24 hours. The
main concern with this package will be the presence of ample low
level mixing leading to low level turbulence and even LLWS at the
KLSE terminal overnight as a strong 850 mb jet re-develops across
the area. With surface gusts expected to linger west of the river,
LLWS conditions will not quite be reached at the KRST terminal but
there will certainly be low level turbulence overnight. The 850
mb jet will move east of the region by daybreak with low level
turbulence/wind shear gradually coming to an end. Surface winds
are expected to decrease by tomorrow morning to between 5-10
kts ahead of an approaching cold front. As the cold front moves
through during the day, winds will quickly shift to the
north/northeast in its wake, staying below 10 kts.

&&

.ARX WATCHES/WARNINGS/ADVISORIES...
WI...None.
MN...None.
IA...None.

&&

$$

DISCUSSION...Barendse
AVIATION...Barendse