459
FXUS63 KARX 271808
AFDARX

Area Forecast Discussion
National Weather Service La Crosse WI
108 PM CDT Fri Jun 27 2025

.KEY MESSAGES...

- Dry weather expected today with clouds decreasing this
  afternoon.

- Warmer temperatures are expected this weekend. Strong to
  severe storms are possible Saturday night and Sunday.

- Drier conditions expected next week.

&&

.DISCUSSION...
Issued at 355 AM CDT Fri Jun 27 2025

Today

We finally get some dry weather today as low pressure moves
east and allows upper ridging and high pressure to build their
way into the upper Midwest. However, low level saturation and
low clouds upstream indicate the low clouds over us will linger
through the morning hours as said low pressure departs, but
begin to clear up in the afternoon.

Warmer Temperatures and Strong to Severe Storms this Weekend

The brief ridging today continues into Saturday allowing for
southerly flow and low level warm air advection. 925hPa
temperatures climb to 24-26C over much of the area on Saturday.
With very little variation in the location of the 24C isotherm
in the 25th-75th percentile spread, there is high confidence in
the temperature forecast Saturday where most areas should reach
the mid to upper 80s with heat indices in the low 90s. There is
less confidence in the temperature forecast on Sunday given the
influence of expected convection.

Instability builds across the Upper Mississippi River Valley
Saturday afternoon under the aforementioned southerly flow.
While it`s still a little far away for a solution from the CAMs,
global deterministic models depict an MCS developing across
Minnesota Saturday and possibly moving into southeastern
Minnesota to west-central Wisconsin Saturday night before
weakening. Damaging winds would be the primary threat.

Instability is then progged to develop across our area
again Sunday, with a mean SBCAPE values of 2500+ J/kg noted in
the 26.12z LREF. Deep layer shear doesn`t appear to be ideal for
more organized convection however, generally only 15-25kts,
with the stronger shear lying to our north. Despite this,
forcing via a surface boundary moving through the region should
be enough for storms to make use of the instability with
damaging wind gusts and large hail possible, in agreement with
the CSU Machine Learning Probabilities, which highlight a
15-30% probability of these hazards as well as a Slight Risk
from the SPC.

Drier Next Week

With northwest flow expected to return next week, drier air
will be ushered into the region, thus favoring drier weather.
However, several shortwaves will traverse the mean flow during
this timeframe, so despite the drier air in place, bouts of
precipitation are still possible, generally a 10-20% chance on
any given day.

&&

.AVIATION /18Z TAFS THROUGH 18Z SATURDAY/...
Issued at 108 PM CDT Fri Jun 27 2025

MVFR conditions improve to VFR later this afternoon and low-level
moisture decreases. VFR conditions persist through the evening,
however as a steep low-level inversion increases with light surface
winds, some fog development will be possible across portions of WI
and along the Mississippi River. As a result, have included a 3sm
group at KLSE for a few hours tomorrow morning. Otherwise, VFR cigs
are expected throughout the rest of the morning on Saturday with
some probability for a complex of decaying thunderstorms to sneak
into the region around 12-15z. There remains significant differences
between the CAMs on how this may evolve though so have not included
any mention in the TAF at this time.

&&

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

&&

$$

DISCUSSION...Falkinham
AVIATION...Naylor