977
FXUS63 KARX 012341
AFDARX

Area Forecast Discussion
National Weather Service La Crosse WI
641 PM CDT Sat Nov 1 2025

.KEY MESSAGES...

- Isolated light showers may develop this afternoon (0-20%).
  Impacts from any showers will be minimal.

- Patchy fog is possible tonight into Sunday morning, primarily
  in river valleys and south of I-90.

- Potential for showers returns Sunday night into Monday
  morning, primarily for areas north of I-90 (20-40%).

&&

.DISCUSSION...
Issued at 151 PM CDT Sat Nov 1 2025

Isolated Light Showers This Afternoon

Isolated light showers may develop during the afternoon hours
today (0-20%) associated with steepened 850-700hPa lapse rates
of 6-7 C/km in the wake of a 500hPa vorticity lobe continuing
to shift southeastward. Some uncertainty as to how steep lapse
rates will be able to get under the cloud cover, but could prove
to be enough to promote at least some shower development given
saturation in the lowest 2km of the atmosphere. Low level
saturation begins to wane by the evening and better lapse rates
move southeast with the upper level pattern, bringing an end to
shower potential.

Patchy Fog Possible Tonight into Sunday Morning

With the brief upper ridging building into the region, some
patchy fog may be able to develop tonight given light winds and
moisture from the recent light rain. However, fog development
largely hinges on if skies are able to clear sufficiently
overnight. If skies are able to clear, fog will be favored
within river valleys and south of I-90 as the 01.12z HREF
highlights a 30-50% probability of visibility less than 1 mile
across these areas. However, there is lower confidence in fog
development for areas west of the Mississippi River as clearer
skies are favored further east.

Shower Potential Sunday Night into Monday Morning

A 500hPa shortwave and associated surface cyclogenesis shifts
eastward over southern Canada Sunday into Monday. As these
features track east, a tightening pressure gradient is expected
to increase 925-850hPa winds with the potential for some of this
momentum to translate to the surface based on 01.15z RAP/HRRR
soundings, leading to some breezy conditions in the afternoon.
Gusts of 25-35 mph are possible, primarily west of the
Mississippi River into north-central Wisconsin.

By Sunday night, a ribbon of positive vorticity and a surface
frontal boundary will be dragged through the region. Southerly
flow ahead of these features will promote warm air advection
along with an axis of increased theta-e nudging into the
Midwest, which could promote some shower development along the
surface front for areas primarily north of I-90. The 01.00z LREF
mean highlights 50-70% probabilities for measurable
precipitation through Monday morning, although this is largely
inflated by the EPS, as the GEFS has a much drier solution,
likely owing to discrepancies in the low level thermal profile
and southern extent of stronger forcing. The GEFS nudges the
850hPa thermal ridge slightly further northeast, resulting in
drier low levels as compared to the EPS and keeps the stronger
positive vorticity advection further north and east. Looking at
the 01.12z HREF, it depicts a solution similar to GEFS,
highlighting lower probabilities for showers. Given the
uncertainty between the ensembles, have gone with the NBM PoPs
of 20-40%, with the greatest potential over northern and central
Wisconsin.

&&

.AVIATION /00Z TAFS THROUGH 00Z MONDAY/...
Issued at 640 PM CDT Sat Nov 1 2025

Skies will gradually clear this evening. This will aid in the
potential of IFR/MVFR ceilings and fog overnight and on Sunday
morning. As winds pick up in the morning, the stratus and fog
will quickly dissipate. In addition, the south winds will gust
into the 15 to 25 knot range.

&&

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

&&

$$

DISCUSSION...Falkinham
AVIATION...Boyne