La Crosse, Wisconsin 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

054
FXUS63 KARX 111047
AFDARX

Area Forecast Discussion
National Weather Service La Crosse WI
547 AM CDT Mon Aug 11 2025

.KEY MESSAGES...

- Morning fog has formed, locally dense, in western/central WI
  and northeast IA. This should dissipate by 8-9am.

- Rain chances (50%) in southwest Wisconsin and adjacent
  northeast Iowa tonight as another system brushes the area. Any
  storms will be able to produce decent rain rates and possibly
  isolated 1" totals in swrn WI overnight, but flooding is not
  currently expected.

- Moderately strong system from the northwest moves through
  Tuesday with scattered showers and storms along it. Cannot
  rule out a stronger afternoon storm in central WI. This
  finally pushes the very potent heavy rain-producing air mass
  out of the region.

- A fairly quiet mid-week leads to a warmer and possibly more
  active weather pattern for storms late week.

&&

.DISCUSSION...
Issued at 325 AM CDT Mon Aug 11 2025

Rain Chances Tonight in Southwest WI and Adjacent Northeast IA

Current radar shows a very active thunderstorm night over
Kansas in the base of a large scale mid-level trough over the
central CONUS. Regional radar shows a number of rotations
within/born/enhanced with the thunderstorms, the most vigorous
over western Neb. This general troughiness and the vigorous wrn
Neb rotation will shift east today and provide a bit of a
moisture transport enhancement into eastern IA and southern WI.
Of interest, the 11.06Z RAP is showing a more vigorous
shortwave trough strength over KS vs previous runs, consistent
with the very visible rotation mentioned above. Also, the new
RAP is more vigorous with the low-level jet over IA tonight as a
result, as that wave moves east. Southwest WI and adjacent nern
IA will be on the very northern edge of this activity and the
instability and main moisture axis, and think scattered storms
will move through that area. Some of these could bring brief
heavier rain rates and cannot rule out a quick inch down there.
At this time it doesnt seem like it would pose a higher threat
for flooding. This activity will continue into the morning
Tuesday before shifting east.

Tuesday`s Rain/Storm Chances, Less Humid Wed/Thu

Good agreement in the model guidance exists on a stronger
system moving through Tuesday from the northwest with moderate
QG-forcing aloft, some marginal instability of about 1500-2000
J/KG MLCAPE and moderate wind shear and straight line
hodographs. The agreement on the CAMS is quite good on a
developing line/area on the front in WI Tuesday. This is
consistent with the ingredients and would think scattered
activity will occur on the front. The latest NBM probs for rain
are very low, probably due to the low PoP bias for light QPF
systems, so have gone toward a blend of the raw operational
models for rain chances (40-50% for now). These systems usually
have trending-upward rain chances as they draw closer.

Cannot rule out a stronger storm in the later afternoon in
central WI before the front moves east as straight line hodographs
are longer suggesting some supercell support. MLCAPE should be
in the 1500 J/Kg range but is skinny with meh mid-level lapse
rates (near 5-5.5C/km)...so not real confident on storm
strength...maybe the top end is 1 inch hail and wind gusts to
50 mph?

Behind the front drier air moves in with more comfortable
conditions for a couple days Wed/Thu. Wednesday looks glorious.

Warming and Possibly More Storms Late Week

A fairly zonal flow with longwave flat ridging builds in for the
late week and weekend. There is pretty good confidence on
southerly flow bringing a fairly high dewpoint (mid 70s?) humid
regime back to the area Friday under strong warm advection.
There would be some vulnerablilty to shortwave trough activity
within the zonal flow regime depending on how poleward the ridge
builds. In the big picture it appears the frontal zone will be
in the WI/MN area with variability on the N/S position. That
front will be the focal point of thunderstorm complexes with
daily building (extreme?) instability in the rich warm sector to
the front`s south.

&&

.AVIATION /12Z TAFS THROUGH 12Z TUESDAY/...
Issued at 542 AM CDT Mon Aug 11 2025

Fog/mist has overspread much of the area (outside of SE
Minnesota) creating MVFR to LIFR CIGs and visibilities. This
areal/valley fog is expected to burn off in the coming hours
with conditions improving to VFR areawide. Fog will again be
possible tonight but conditions don`t look quite as favorable
as today and will likely have a smaller areal extent. Have
included some BR and MVFR visibilities at LSE late in the
period to account for this possibility but left RST VFR as there
is more uncertainty across SE Minnesota. Light winds at less
than 10 kts out of the west are expected for much of today
before becoming more southerly into the overnight hours.

&&

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

&&

$$

DISCUSSION...Baumgardt
AVIATION...Barendse