739
FXUS63 KARX 281902
AFDARX

Area Forecast Discussion
National Weather Service La Crosse WI
202 PM CDT Thu Aug 28 2025

.KEY MESSAGES...

- Small shower and thunderstorm chances (20 to 35%) for Friday.

- Next chance (30 to 45%) for widespread rain will be midweek.

- High temperatures remain in the mid to upper 70s through Tuesday.

&&

.DISCUSSION...
Issued at 202 PM CDT Thu Aug 28 2025

Today-Friday: Low Rain Chances

In the wake of a shortwave trough that moved through the region
earlier this morning, a weak boundary is situated from central
Minnesota into northwestern Illinois. Along the boundary is weak
surface convergence, PWATs near 1", and up to a few hundred joules
of MUCAPE. There is some capping over the region, roughly 25 to 75
J/kg of CIN, that will need to be overcome for any shower or storm
to form. That being said, some of the CAMs have a few showers
popping up, however confidence is not high enough to put mentionable
PoPs in. Heading into Friday, a shortwave trough moves through the
area. Around 750 to 1250 J/kg of MLCAPE will allow for scattered
showers and thunderstorms to be possible. With weak shear, severe
weather is not expected.

Saturday-Thursday: Mostly Dry Labor Day Weekend, Rain Chances
and Cooler Weather Return Midweek

By Saturday, a high will be positioned over southern Canada. A low
will undercut this high and move into the northern Plains. This will
bring the potential for scattered showers and storms, however the
best potential will be for areas along and west of I-35. High
temperatures from today through Tuesday largely remain in the mid to
upper 70s. Ensemble and deterministic guidance continues to be in
agreement that a closed low will move into the Upper Mississippi
Valley and Great Lakes Regions midweek. This will bring increased
chances (30 to 45%) at widespread rain. In addition to the rain
chances, much cooler weather could be on the way. This is largely
dependent on how deep the low gets. The Grand Ensemble has 850mb
temperatures around 5C Thursday morning. This would translate to low
temperatures in the low to mid 40s across the CWA.

&&

.AVIATION /18Z TAFS THROUGH 18Z FRIDAY/...
Issued at 1224 PM CDT Thu Aug 28 2025

Main taf concern through the taf period is fog development in river
valleys tonight into Friday morning. Surface ridge provides light
winds and mostly clear skies for much of the area tonight.
However...there are hints the scattered clouds over central
Wisconsin will expand over the rest of the forecast area
tonight. This could limit or inhibit the development of fog in
river valleys tonight. Depending on how widespread the cloud
cover is or where skies are clear...will determine fog
development in river valleys. If fog forms before clouds
form...visibility will be reduce to LIFR. If clouds expand over
the area...RST/LSE taf sites could see MVFR/IFR conditions. For
now...expect fog to form in river valleys and to be IFR
at LSE taf site after 09z Friday. Have brought in broken clouds
after 15z Friday at both RST/LSE taf site. Have kept ceilings
above 3000 feet. Though we could see a brief period of MVFR
conditions Friday morning.

&&

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

&&

$$

DISCUSSION...Cecava
AVIATION...DTJ