165
FXUS63 KARX 062332
AFDARX

Area Forecast Discussion
National Weather Service La Crosse WI
532 PM CST Thu Nov 6 2025

.KEY MESSAGES...

- Storm system promises snow/rain for parts of the region Saturday.
Currently, the favored track drops any ptype from I-90 south. Snow
accums from a few hundreths to near 1" (20% chances for that) on
grassy surfaces are possible. However, while the track is coming
more in focus, there are hints it could shift even further south,
and thus so would the main band of light snow. Stay tuned.

- Cold weekend into start of new week still expected with highs only
in the 30s Sun/Mon.

&&

.DISCUSSION...
Issued at 140 PM AM CST Thu Nov 6 2025

> END OF WORK WEEK: some rain chances, mostly across WI. Seasonable.

- TONIGHT: upper level shortwave trough remains on track to slip
east from the northern plains today, sliding across the upper
mississippi river valley tonight. Not a well defined system, but it
does bring solid low level thermodynamics and a north-south running
sfc front with it. What it doesn`t have, at least initially, is
saturation along the southern flank of the sfc boundary. Low level
moisture transport ahead of the system eventually pushes along the
boundary, but mostly as it moves into WI. This has been a consistent
signal in the models over the past few days. The upshot is that pcpn
struggles to manifest until this happens, and thus rain chances are
mostly confined to eastern IA and WI. Locally, this is roughly from
around the Mississippi River eastward. Amounts continue to look
minimal (under 1/10").

- FRIDAY: as the system and its sfc low exits east Fri a sfc trough
will hang westward, still lingering across the region as it sinks
southeast. Cyclonic flow persists a loft with a few ripples likely
dropping across the region. Add in low level cold air advection and
favorable 1000:850 mb lapse rates of 7-8 C/km and you have a good
mix of lift for shower production - if you have enough saturation.
RH fields and time/height x-section suggest there will be - moreso
across northern/central portions of MN/WI. NBM still struggling to
produce any pcpn chances (low QPF issues the most likely culprit)
while the preponderance of models (CAMS, blends, ensembles) suggest
at least small chances into the I-94 corridor. Will paint low end
chances (20%) with this in mind. These chances could sag farther
south and/or increase if current forecast conditions continue to
bear out.



> WEEKEND/EARLY NEXT WEEK: COLD! Rain/snow Saturday likely. Some
snow accumulations (cold, grassy surfaces) favored mostly along/south
of I-90. Track of storm NOT locked in yet - could shift.

- PRECIPITATION CHANCES: models starting to "settle in" to a favored
track for a storm system slated to roll across portions of the area
Sat/Sat night. Latest GEFS/EPS positioning the systems` sfc low
showing more consolidation in their members - tracking it west-east
across northern MO Sat afternoon. Not a strong low, but this track
lays out the bulk of the related pcpn across IA/northern IL,
reaching northward into the I-90 corridor. Should note that there
still are a few members in each ensemble suite that want to edge
this system even farther south - potentially south enough for the
pcpn and/or main snow region to miss the local forecast area
completely.

Messy layout of related Fgen, although low levels (900:800mb) do sit
in a west-east orientation just north of the sfc low. Decent QG
convergence through the layers with the parent upper level shortwave
trough. Quick hitter, not "wound up", but ample lift-saturation for
a swath of pcpn. What falls is another question.

With the current favored track and the southward intrusion of much
colder air - the northern fringe of the pcpn shield should be snow.
The majority of GEFS and EPS members favor at least some minor
accumulations (I-90 south), but some high end outliers suggest a few
inches can`t be ruled. Moreso the GEFS than EPS, and less than 5% of
the members. In addition, grounds are warm and melting of snow
should be expected. Any accums will likely hold to the colder,
grassy surfaces. Will run with the NBM QPF and related snow totals
for now.

Secondary shortwave right on the heals of this first feature could
produce another area of light snow/flurries which currently would
track southeast across IA Sat night. Minimal accumulations (if any)
with this feature.

Lastly, with the trough exiting east but cyclonic flow persisting
Sunday, can`t rule out a few flurries/scattered snow showers where a
mix of weak perturbations...favorable low level lapse rates and
linger sfc boundaries interact. Currently, this would place northern
WI in the more favored area.

- TEMPERATURES: slug of cold, Canadian sourced air still on track to
drop southward across the upper mississippi river valley starting
sat, reinforcing the chill with another shot of cold for sun/mon.
850 mb temps slated to fall from around +5C at 00z this evening to
-5 C by 12z Sat and then -12 C by 12z Sun. 850 mb temp anomalies
continue to hover around -1.5 in the NAEFS and EC with no EFI or SoT
for MaxTs. It`s a cold airmass, coldest of the young fall season,
but not excessively so for early November. Grand Ensemble still
holding at <5% chance for any location warming out of the 30s
Sun/Mon with many locations struggle to creep above freezing Sunday.



> SECOND HALF OF NEXT WEEK: moderating temps, trending dry

Long range trends in the GEFS and EPS continue to show broad upper
level ridging, increasing heights moving into the second half of
next week. WPC clusters show this, but with a variety of placements
and strengths. Sensible weather outcomes would be for moderating
temps - more inline with the seasonable norms. Shortwave activity
would likely be shuffled north of the region - but highly dependent
on ridge position/strength. Trends at this time suggest a dry period
locally.

&&

.AVIATION /00Z TAFS THROUGH 00Z SATURDAY/...
Issued at 532 PM CST Thu Nov 6 2025

A cold front will move through the area tonight. As the
saturation increases ahead of this front, more and more showers
will develop along and ahead of it. These showers will affect
KLSE between 08.01z and 08.04z. Other than 3-6K ceilings and
shift in the winds to the west no impacts are expected.

On Friday afternoon, MVFR ceilings will move into southeast
Minnesota and northeast Iowa. These ceilings will move into KRST
around 07.22z.

&&

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

&&

$$

DISCUSSION...Rieck
AVIATION...Boyne