Severe Thunderstorm Warning 103, NWS La Crosse, WI

Area Forecast Discussion
National Weather Service La Crosse WI
652 PM CDT Wed Jul 31 2024

.KEY MESSAGES...

- Strong to severe storm threat tonight with some lingering
  storms on Thursday.

- Continued warm into the weekend but some signal for drier and
  cooler weather later next week.

&&

.DISCUSSION...
Issued at 205 PM CDT Wed Jul 31 2024

TONIGHT and THURSDAY:

Focus going into the evening is convective storm threat, including
location, timing, and intensity for our area. Still lots of details
to work out. Per usual, convective allowing models are all over the
place and struggling catching up with reality this afternoon.

Tracking mid level trough across the Dakotas with several short
waves steering main convective threats. Northern wave is leading to
convection across western Minnesota but short term guidance still
suggests this will take a turn to the southeast tonight, riding the
700 mb cap and better CAPE gradient. Unsure if this will happen as
storms may stay ahead of this feature, albeit elevated in nature.
Meanwhile another feature is lifting out of eastern Nebraska that
may be bigger player as associated front edges into higher MUCAPE
axis from eastern Nebraska northward along SD-MN border. Shear
values are also higher closer to the wave with far shorter and
chaotic hodographs the further east you go. Again, warm mid level
temperatures may be limiting convection initially but still
expecting it to fill in as afternoon goes on.

While it makes sense that storms would erupt this afternoon along
associated front and mainly track west and south of us, am a little
concerned about convection across northern areas and how that may
play into this. In any event, could be looking at a strong to severe
storm risk further north and east, and perhaps earlier, than expected,
especially if a well developed cold pool can form. Damaging
wind continues to be main threat with bowing segments.

Wave from overnight will still be lingering across Wisconsin on
Thursday, which will likely force additional showers and storms,
especially ahead of it. Higher CAPE values will be shunted off to
the southeast taking higher risk of any severe storms with it.
But could still see enough low level instability and favorable
vorticity fields for non supercell landspout set up if strong
enough storm can form under passing low.

FRIDAY into NEXT WEEK:

Mean upper ridge placement remains fairly consistent across the
western CONUS at least into early next week before we see more
height falls across the Upper Midwest next week. This keeps the
western Great Lakes along the edge of the cap /warmer air to the
southwest/ and perhaps along a frontal boundary.

Difficult to put any detail into timing and location this far in
advance, but any short waves traveling through this stronger mid
level flow on northeast edge of ridge could lead to a more organized
convective risk for us.

Medium range guidance diverges later in the forecast period, but one
consistency is idea of a bit more amplification in flow pushing
cooler and drier into region from the northwest. This would
lead us into a drier and cooler regime. Certainly ensembles
suggest CAPE values among members are highest in short term with
no real signal for higher instability later in forecast period.

&&

.AVIATION /00Z TAFS THROUGH 00Z FRIDAY/...
Issued at 653 PM CDT Wed Jul 31 2024

A challenging convective forecast heading into tonight. Pop up
showers and storms currently south of the Twin Cities are on a
trajectory toward RST and LSE through the next couple hours, but
unsure if this cluster will maintain its intensity as it
approaches. Otherwise the main round of more widespread storms
associated with a shortwave out to our west is expected to sweep
eastward into the TAF sites overnight between approximately
06-10Z. This round of storms will be on a weakening trend as it
moves east overnight. Thereafter, a lingering 30 to 40% chance
for showers and thunderstorms through Thursday morning with the
shortwave overhead, increasing to a 70% chance in the afternoon
with increasing daytime instability. Tried to tie TS mention in
the TAFs to the most likely timeframes.

Other aviation concern will be potential for MVFR ceilings
Thursday morning. RST would have a higher likelihood of going
MVFR, but can't rule out the possibility at LSE for a short
time.

&&

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

&&

DISCUSSION...Shea
AVIATION...Kurz

Hazardous Weather Outlook
National Weather Service La Crosse WI
319 AM CDT Wed Jul 31 2024

IAZ008>011-018-019-029-030-MNZ079-086>088-094>096-WIZ017-029-
032>034-041>044-053>055-061-011000-
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-
319 AM CDT Wed Jul 31 2024

This Hazardous Weather Outlook is for portions of southeast
Minnesota...northeast Iowa and southwest into central Wisconsin.

.DAY ONE...Today and Tonight

Thunderstorms tonight. A few could be strong to severe, mostly
this evening and west of the Mississippi river. Damaging winds
are the main threat.

.DAYS TWO THROUGH SEVEN...Thursday through Tuesday

Storm chances persist Thursday. Organized severe weather is not
expected.

.SPOTTER INFORMATION STATEMENT...

Rainfall or severe reports are appreciated.

.EMERGENCY MANAGEMENT COORDINATION...

No webinar is scheduled.

Rieck

Preliminary Local Storm Report
National Weather Service La Crosse WI
740 PM CDT Wed Jul 31 2024

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

0731 PM     Tstm Wnd Gst     1 NW Zumbro Falls       44.29N 92.44W
07/31/2024  E60 MPH          Wabasha            MN   Fire Dept/Rescue

0731 PM     Hail             1 WNW Zumbro Falls      44.29N 92.44W
07/31/2024  E1.75 Inch       Wabasha            MN   Fire Dept/Rescue

&&

Preliminary Local Storm Report
National Weather Service La Crosse WI
756 PM CDT Wed Jul 31 2024

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

0733 PM     Hail             3 NNE Zumbro Falls      44.32N 92.41W
07/31/2024  E1.75 Inch       Wabasha            MN   Trained Spotter

&&

db

Preliminary Local Storm Report
National Weather Service La Crosse WI
757 PM CDT Wed Jul 31 2024

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

0738 PM     Hail             5 NNE Zumbro Falls      44.35N 92.40W
07/31/2024  E0.75 Inch       Wabasha            MN   Trained Spotter

            Hail up to penny size.

&&

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