Severe Thunderstorm Warning 26, NWS La Crosse, WI

Area Forecast Discussion
National Weather Service La Crosse WI
658 PM CDT Mon Apr 28 2025

.KEY MESSAGES...

- Late this afternoon/this evening, severe weather threat
  remains over the area with timing to be mainly 6 PM to
  midnight. Storms will move over the area and would be in a
  very favorable environment for rapid development. These storms
  would have the potential to produce strong (EF2+) tornadoes
  and hail in excess of 2 inches in diameter. Severe weather
  threat will be across the whole area, however the higher
  threat will be over southeast Minnesota and western
  Wisconsin.

- Another round of showers and a few storms Wednesday afternoon
  into Thursday. QPF amounts expected to be less than a half of
  an inch.

- Warming trend this weekend. High temperatures warming into the
  70s possibly near 80 in a few locations by early next week.

&&

.DISCUSSION...
Issued at 241 PM CDT Mon Apr 28 2025

Late This Afternoon through Tonight

The atmosphere continues to evolve rapidly across the region ahead
of a stacked low pressure area over the ND/SD border at 18Z.
Surface dewpoints are surging northward and northeast into the area
with 60F+ now into central MN trailing southeast to the Miss river
and into SW WI.  GOES visible imagery clearly shows the slightly
capped warm sector ahead of a dry line and wind shift over SW MN.
Clearing and warming extended east about 3 counties to just west of
Interstate 35 at 1830Z with SPC mesoa indicating MLCAPE around
2500J/Kg. This favorable sector of instability will continue
to progress east across southern MN today, arriving by early
evening. The wind shear for tornadoes is more favorable slightly
further east of the storms in the cloud/capped region /300-400
ms/s2 0-1km SRH/ in the southerly and slight southeast
surface wind flow. Just ahead of the storms in SW MN, the winds
veer to SSW lowering the SRH to much more modest and less tornadic
values. Some veering in the low-level wind flow is expected to occur
over southeast MN and northeast IA when these storms move in within
the 6-9 pm window with still a perky ~250 m2/s2 0-1km SRH expected.
At some point near our forecast area, the discrete supercells are
still expected to congeal moving the threat from strong /EF2+
tornado possible/ to a QLCS tornado threat as the evening
progresses. With ample deep shear and the forcing, large
hail is a threat with the supercells before transitioning to an
increasing line/wind threat.

The area further east of the incoming supercells/line, mainly WI, is
the lower confidence area with near-surface temperatures warming in
the clearing in central WI. Through about 4 pm, elevated modest
MUCAPE of 1k J/Kg will promote isolated severe hail reports. After
that time, depending on the differential heating boundary in
SW/Central WI intensity, could support surface-based storms and the
richer low-level helicity environment to produce a tornado. We will
be watching closely for this as the afternoon wears on. With
confluent flow noticed in the observations and storm growth occurring
entering this zone, seems we are realizing our round 1 messaging
threat in western WI.

Tuesday through Thursday

Surface ridge builds into the region Tuesday. Subsidence underneath
surface ridge should allow skies to clear and winds to
diminish Tuesday afternoon across the forecast area.

Upper level closed low weakens and tracks slowly into the Southern
Plains Wednesday into Thursday. Impulses eject out of the upper
level closed low into the central Plains/Upper Mississippi River
Valley. There is enough forcing/moisture convergence with each
impulse and will spread showers into the forecast area. Instability
is limited and confined to the southern parts of the forecast area
where a few storms could develop Wednesday night into Thursday.

Thursday night through Monday

Main forecast concerns are on and off small chances of showers
through the forecast period. Upper level pattern goes from upper
level trough over the Upper Great Lakes region early in the period
then southwesterly flow aloft develops over the central United
States over the weekend. As upper level trough tracks east into the
northeast United States small chance of showers are possible Friday.
Shortwave ridge builds into the Upper Mississippi River Valley
Saturday and mainly dry weather can be expected. A weak piece of
energy embedded in the southwesterly flow aloft will move into the
Upper Midwest/Upper Mississippi River Valley Sunday into Monday.
Weak moisture transport/convergence and weak lift associated with
the piece energy will produce small chance of showers both days.
Temperatures will be on a warming trend for the weekend...as
southerly flow aloft advect warmer temperatures into the forecast
area. High temperatures will be in the middle 50s to lower  60s
Friday and warm into the 70s by Sunday into Monday.

&&

.AVIATION /00Z TAFS THROUGH 00Z WEDNESDAY/...
Issued at 645 PM CDT Mon Apr 28 2025

A line of storms to the west of Rochester with additional
showers over parts of western Wisconsin at the start of the TAF
period. The storms will continue to move northeast, but push
east through the evening hours. The hail and higher wind reports
have been sporadic, so for now did include some stronger gusts
and will add hail and stronger gusts if needed. Did mention low
level wind shear at KLSE early this evening. VFR ceilings with
MVFR/IFR ceilings with the thunderstorms. Conditions will
improve to VFR for a few hours, however MVFR ceilings are
forecast to return with the wind shift to the northwest.
Northwest winds decrease Tuesday afternoon with winds decreasing
to 10 to 15kt.

&&

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

&&

DISCUSSION...Baumgardt/DTJ
AVIATION...Zapotocny

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Preliminary Local Storm Report
National Weather Service La Crosse WI
703 PM CDT Mon Apr 28 2025

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0652 PM     Hail             Kasson                  44.03N 92.75W
04/28/2025  E1.00 Inch       Dodge              MN   Trained Spotter

            Relayed via Emergency Manager.

&&

KB

Preliminary Local Storm Report
National Weather Service La Crosse WI
723 PM CDT Mon Apr 28 2025

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0720 PM     Hail             4 SE Douglas            44.07N 92.51W
04/28/2025  E0.70 Inch       Olmsted            MN   Trained Spotter

&&

APF

Preliminary Local Storm Report
National Weather Service La Crosse WI
725 PM CDT Mon Apr 28 2025

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0722 PM     Hail             3 NW Rochester          44.05N 92.52W
04/28/2025  E0.75 Inch       Olmsted            MN   Trained Spotter

&&

APF

Preliminary Local Storm Report
National Weather Service La Crosse WI
726 PM CDT Mon Apr 28 2025

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0723 PM     Hail             3 ESE Douglas           44.09N 92.53W
04/28/2025  E0.75 Inch       Olmsted            MN   Emergency Mngr

&&

KB

Preliminary Local Storm Report
National Weather Service La Crosse WI
802 PM CDT Mon Apr 28 2025

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0756 PM     Hail             Austin                  43.67N 92.97W
04/28/2025  M0.25 Inch       Mower              MN   Trained Spotter

&&

CZ