Severe Thunderstorm Warning 145, NWS La Crosse, WI

Area Forecast Discussion
National Weather Service La Crosse WI
708 PM CDT Wed Jul 1 2026

.KEY MESSAGES...

- Strong to severe storms are expected across the region
  primarily this evening into tonight. The primary hazards will
  be damaging winds and heavy rain.

- Additional showers and storms are possible Thursday afternoon
  (30-60%), but when/where they develop largely hinges on the
  evolution of storms tonight.

- Seasonable temperatures for the holiday weekend, shower/storm
  chances exist (40-60%).

&&

.UPDATE...
Issued at 705 PM CDT Wed Jul 1 2026

As alluded to in earlier discussions, the remnant cloud shield
from our morning convection has played havoc with the timing and
threat assessment for thunderstorm development this afternoon.
Multiple failed updrafts have occurred over the last few hours,
though several stronger cells have managed to persist by Eau
Claire with a new cell developing by Mitchell County. Overall
trends are that these continued CI attempted will erode what
remains of the cap and widespread convection should develop
along a weakly convergent corridor from southern MN into
western WI over the next hour or two and gradually sag
southward with time (though with the upwind propagation vector
facing east, this southward propagation may be very slow).
Heavy rain looks to be the main threat with these cells
throughout the evening and overnight, with any severe weather
threat (wind/hail/tornado) expected to cease by midnight.

&&

.DISCUSSION...
Issued at 205 PM CDT Wed Jul 1 2026

This Afternoon - Thursday Morning: Severe Storm Potential

A fairly challenging forecast riddled with uncertainty exists
over the next 24 hours. Model guidance has largely struggled to
resolve this morning's storms and the influence they'll have on
the atmosphere as we head into the overnight hours.

Observational and satellite analysis suggests that a surface
boundary exists generally from northeast Iowa into north-central
Wisconsin, a slight southern shift from earlier CAM solutions,
owing to outflow and cooling from this mornings convection.
South of this boundary, an unstable airmass is in place across
portions of northeast Iowa and southwest Wisconsin characterized
by SBCAPE values exceeding 2500 J/kg below effective bulk shear
values of 35-40kts. Differential heating and/or outflow
boundaries that have developed during the day may provide enough
forcing for storm initiation which could then pose a large hail
and damaging wind risk given DCAPE values exceeding 800 J/kg
and slight elongation in model hodographs.

This boundary is expected to be the primary catalyst for
convective development this evening as a 500hPa shortwave
trough moves overhead and a strengthening 850hPa low level jet
extending northward from Nebraska nudges into the boundary.
Given the slight southern shift to the boundary, current
expectations are for convective initiation further south than
previous forecasts, more in line with solutions such as the
01.12z ARW/NAMNest. However, how far south this boundary gets
and/or if it shifts back northward (and thus the location of
convective development) will be dependent on how much clearing
we see over the next few hours.

Despite the slight changes in location, there has been little
to no change from a hazard perspective. Given a boundary
parallel 0-6km shear vector, expectations are for a more linear
storm mode with damaging winds of 60-80 mph the primary threat
although a few tornadoes cannot be ruled out within favorably
oriented bowing segments. Any discrete potential will be favored
with convective initiation along the boundary which would be
more favorable for large hail and additional tornado potential.

Heavy rainfall potential continues to be a concern along and
just north of the aforementioned boundary where storm motions
along the boundary are favorable for training storms. High PWATs
of 1.7-1.9 inches exist over Iowa this afternoon and will be
advected into the boundary along the aforementioned low level
jet which combined with warm cloud depths of 10-14kft should
result in some heavy rainfall. An additional 1-3 inches of rain
is possible (20-50%) with these storms with the 01.12z HREF LPMM
even suggesting some areas could see 4-5 inches if conditions
line up just right. That said, the southern shift of the
boundary should result in these higher totals south of the
highest rain axis seen with this morning's convection which
would limit flooding risk over these areas.

Thursday Afternoon - Friday: Severe Storm Potential Continues

As if the last few days didn't have enough showers/storms,
additional development is possible Thursday afternoon with the
01.13z NBM suggesting 30-60% probabilities for measurable
precipitation. That said, a lot of disagreement exists between
the short-term guidance regarding timing/location due to a lot
of dependence on how storms evolve tonight/Thursday morning. The
thermodynamic and kinematic environments do appear favorable
for strong/severe storms if/when they develop (2000-3000 J/kg
MLCAPE and 35-40kts of 0-6km bulk shear) although these
parameters are slightly displaced from each other. Storm mode
will largely be a function of where storms develop, but current
expectations are for a more multicell-type mode given the
displacement of instability and deep-layer shear.

Holiday Weekend - Early Next Week: Seasonable Temperatures Return
With Additional Shower/Storm Potential

Models continue to indicate a more zonal pattern developing
across the United States as the ridge that's been in place this
week breaks down and moves eastward. This will allow for several
shortwave troughs to traverse the mean flow through the holiday
weekend resulting in periodic shower/storm chances (50-70%).
We're currently highlighted in a level 1/5 risk for severe
weather on Friday July 3 by the SPC while AI/ML guidance
highlights some low potential for severe weather on Independence
Day. Apart from the storm potential, temperatures continue to
trend towards normal with high temperatures in the mid 80s.

&&

.AVIATION /00Z TAFS THROUGH 00Z FRIDAY/...
Issued at 600 PM CDT Wed Jul 1 2026

Widespread showers and thunderstorms move through the region
tonight, becoming more scattered (40-60% coverage) in nature as
we go through the day on Thursday. IFR visibilities are
possible in the stronger storms along and south of an RST to DLL
line overnight. Otherwise, look for mainly VFR conditions away
from these storms with a few pockets of MVFR ceilings possible
at times through the period. Winds remain mainly from the south
to southwest at 5-10 kts.

&&

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

&&

UPDATE...Skow
DISCUSSION...Falkinham
AVIATION...Skow

Hazardous Weather Outlook
National Weather Service La Crosse WI
535 PM CDT Wed Jul 1 2026

IAZ008>011-018-019-029-030-MNZ079-086>088-094>096-WIZ017-029-
032>034-041>044-053>055-061-030245-
Mitchell-Howard-Winneshiek-Allamakee-Floyd-Chickasaw-Fayette-
Clayton-Wabasha-Dodge-Olmsted-Winona-Mower-Fillmore-Houston-
Taylor-Clark-Buffalo-Trempealeau-Jackson-La Crosse-Monroe-Juneau-
Adams-Vernon-Crawford-Richland-Grant-
535 PM CDT Wed Jul 1 2026

This Hazardous Weather Outlook is for portions of northeast Iowa
and southwest Wisconsin.

.DAY ONE...This Afternoon and Tonight

Strong to severe thunderstorms are expected later this evening and
tonight. Damaging winds will be the main threat with these
storms, along with large hail, heavy rain, and possibly a few
tornadoes.

.DAYS TWO THROUGH SEVEN...Thursday through Tuesday

The threat for severe thunderstorms continues on Thursday and
possibly into the weekend.

.SPOTTER INFORMATION STATEMENT...

May be needed this evening and at times through the weekend.

.EMERGENCY MANAGEMENT COORDINATION...

No webinar is scheduled.

KDS

Special Weather Statement
National Weather Service La Crosse WI
722 PM CDT Wed Jul 1 2026

IAZ008-009-MNZ094-020100-
Howard IA-Mitchell IA-Mower MN-
722 PM CDT Wed Jul 1 2026

...A STRONG THUNDERSTORM WILL IMPACT NORTHERN MITCHELL...NORTHWESTERN
HOWARD AND SOUTHEASTERN MOWER COUNTIES THROUGH 800 PM CDT...

At 722 PM CDT, Doppler radar was tracking a strong thunderstorm over
Stacyville, or 10 miles north of Osage, moving northeast at 35 mph.

HAZARD...Wind gusts up to 40 mph and penny size hail.

SOURCE...Radar indicated.

IMPACT...Gusty winds could knock down tree limbs and blow around
         unsecured objects. Minor hail damage to vegetation is
         possible.

This strong thunderstorm will be near...
  Le Roy around 735 PM CDT.

Other locations impacted by this storm include Lake Louise State
Park, Meyer, Mitchell, County Roads 4 And 3, Brownville, County Roads
T 54 And A 31, Pioneer State Park, McIntire, Highway 218 And County T
40, and Little Cedar.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If outdoors, consider seeking shelter inside a building.

This storm may intensify, so be certain to monitor local radio
stations and available television stations for additional information
and possible warnings from the National Weather Service.

A Severe Thunderstorm Watch remains in effect until 100 AM CDT for
north central and northeastern Iowa...and southeastern Minnesota.

&&

LAT...LON 4331 9289 4340 9295 4364 9245 4333 9245
TIME...MOT...LOC 0022Z 241DEG 28KT 4343 9273

MAX HAIL SIZE...0.75 IN
MAX WIND GUST...40 MPH

Naylor