Special Weather Statement, NWS La Crosse, WI

Area Forecast Discussion
National Weather Service La Crosse WI
700 PM CDT Tue May 25 2021

.UPDATE...
Issued at 148 PM CDT Tue May 25 2021

** Re: storm potential this afternoon and eve **

This afternoon convective initiation continues to be somewhat murky.
Latest trends in the 18-19Z GOES satellite Day Cloud Distinction
show an area of very weak cumulus development in southeast MN and wc
WI near KONA /Winona/ and northeast. This is along the building SW-
NE CAPE pool of ~1500 J/KG all well out ahead of the surface
dryline/cold front in MN. Cumulus was building and partially
glaciating trying to initiate, but has trended down in the last 30
mins. This matches well with a weaker but steady- state deeper but
broad moisture convergence region extending from the ongoing
convective echo east of Medford, WI, to Winona MN to Mason City per
SPC mesoa page. Day Cloud Distinction also showing growing cumulus
along several frontal/near frontal boundaries across NW WI and
eastern MN...roughly I-35 in MN KAEL- KMSP-KDLH.

Wind shear across the area has increased with 0-6km bulk shear
~40kts or more north of I-90 per RAP and GOES derived cloud motion
winds. Thus, supercell modes will be favored, and with storm motion
45-90 degs to front, should see discrete cells for a period after
initiation.

With aforementioned deeper weak convergence north and just west of
La Crosse, would think lower-end storms could occur as capping is
minimal, but thinking is that this area would have a lower threat of
severe storms due to less sustained convergence. The cold front, now
located further west along the growing cumulus fine lines near I-35
will continue east and provide a late afternoon severe storm threat
in western WI, far southeastern MN /matches western edge of SPC SLGT
risk well/. Would think the frontal convergence and dewpoint
gradient will sharpen a bit in the coming hours, a bit steeper lapse
rates and more large scale lift with shortwave trough energy will
shift in. Overall, the frontal convergence is not super impressive
with broad rounded trough at the surface. This will impact storm
coverage.

Parameters marking the I-90 and north area well for large hail and
wind potential. Large hail parms suggest 2" hail possible there.
Hodographs per current 88Ds at KMPX/KARX are straight line from 0-
2km and RAP hodos still carry small curvature in the 0-1/0-3km
layer. SPC Mesoa Sig Tor Parameter ~1 north of I-90 which confirms a
lower, entry level tornado risk currently. This may grow to ~2 with
a bit of backing, should it occur, which is more likely north of I-
94 later. Thus, hail and wind threats seem on target for our
messaging. Further south of I-90 the shear decreases but is still
favorable for severe storms - just marginal supercellular -
multicellular more favored...early eve timing.

.SHORT TERM...(Wednesday and Friday)
Issued at 215 PM CDT Tue May 25 2021

WET THU/THU NIGHT: Another shortwave is progged to move due east
from the PAC NW tonight, spinning across the upper mississippi river
valley thu/thu night. Some ripples in the flow could kick out of the
trough over the desert SW, preceding the NW shortwave across the
region. 30-40 kt 850 mb jet to feed the system. The mix of
lift/moisture should lead to a broad expanse of rain. Little if any
instability to work with, so thunder threat looks limited at this
time. In addition, while the low level moisture transport noses into
the region, warm cloud depths only peak around 3500 m while sfc pws
top out around 1 1/4". Should see decent rainfall with 1/2 to 1" or
so, but potential for more than a good soaker (ie, flooding
concerns) looks low.

TEMPS: with the passage of the dry line/cold front tonight, colder
air starts to filter in from the north, with the main push of cold
air coming in Thu/Fri. Widespread rain/clouds will also work to keep
temps unseasonably cool. Highs still looking like they will struggle
into the 50s both those days - a marked contrast from recent days
when lows bottomed out in the 60s.

.LONG TERM...(Saturday through Tuesday)
Issued at 215 PM CDT Tue May 25 2021

The GFS and EC both favor shortwave upper level ridging come Friday,
quickly sliding east/flattening that ridge out with west-east
running shortwave across southern Canada. Uncertain whether that
shortwave will sparking any pcpn sat night/early sun. Not much qpf
in the models, and still have an exiting sfc high to contend with.

A better shot for rain could come on Memorial day with some
agreement between the GFS and EC with a piece of upper level energy
dropping out of southern Canada and across the region. The GFS
doubles up with advancing more shortwave energy into the area, out
of a trough over the desert SW. Likely a lingering sfc front will
come into play too. The EC leans more on a split flow type
evolution, keeping more of its qpf across the north and south. The
more robust GFS is widespread with its chances. Several of the EC
ensemble members mimic the GFS's take though, with bulk of the GEFS
members also siding toward good chances to get wet.

The cool temperatures will persist, although show some (meager)
warming as we push into the new work week. Could see a return to at
or above normal temps by the following weekend.

&&

.SHORT TERM...(Wednesday and Friday)
Issued at 215 PM CDT Tue May 25 2021

WET THU/THU NIGHT: Another shortwave is progged to move due east
from the PAC NW tonight, spinning across the upper mississippi river
valley thu/thu night. Some ripples in the flow could kick out of the
trough over the desert SW, preceding the NW shortwave across the
region. 30-40 kt 850 mb jet to feed the system. The mix of
lift/moisture should lead to a broad expanse of rain. Little if any
instability to work with, so thunder threat looks limited at this
time. In addition, while the low level moisture transport noses into
the region, warm cloud depths only peak around 3500 m while sfc pws
top out around 1 1/4". Should see decent rainfall with 1/2 to 1" or
so, but potential for more than a good soaker (ie, flooding
concerns) looks low.

TEMPS: with the passage of the dry line/cold front tonight, colder
air starts to filter in from the north, with the main push of cold
air coming in Thu/Fri. Widespread rain/clouds will also work to keep
temps unseasonably cool. Highs still looking like they will struggle
into the 50s both those days - a marked contrast from recent days
when lows bottomed out in the 60s.

.LONG TERM...(Saturday through Tuesday)
Issued at 215 PM CDT Tue May 25 2021

The GFS and EC both favor shortwave upper level ridging come Friday,
quickly sliding east/flattening that ridge out with west-east
running shortwave across southern Canada. Uncertain whether that
shortwave will sparking any pcpn sat night/early sun. Not much qpf
in the models, and still have an exiting sfc high to contend with.

A better shot for rain could come on Memorial day with some
agreement between the GFS and EC with a piece of upper level energy
dropping out of southern Canada and across the region. The GFS
doubles up with advancing more shortwave energy into the area, out
of a trough over the desert SW. Likely a lingering sfc front will
come into play too. The EC leans more on a split flow type
evolution, keeping more of its qpf across the north and south. The
more robust GFS is widespread with its chances. Several of the EC
ensemble members mimic the GFS's take though, with bulk of the GEFS
members also siding toward good chances to get wet.

The cool temperatures will persist, although show some (meager)
warming as we push into the new work week. Could see a return to at
or above normal temps by the following weekend.

&&

.AVIATION...(For the 00Z TAFS through 00Z Wednesday evening)
Issued at 656 PM CDT Tue May 25 2021

Thunderstorms have pushed to the northeast of the TAF sites,
however additional storms are building over north central Iowa and
trying to build northeast. For now, will not mention storms at
KLSE. Southwest winds 15kts will veer to the west 5 to
15kts...becoming northwest and increasing Wednesday during the
morning with gusts 20 to 25kts at KRST.

&&

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

UPDATE...Baumgardt
SHORT TERM...Rieck
LONG TERM....Rieck
AVIATION...Zapotocny

Hazardous Weather Outlook
National Weather Service La Crosse WI
124 PM CDT Tue May 25 2021

IAZ008>011-018-019-029-030-MNZ079-086>088-094>096-WIZ017-029-
032>034-041>044-053>055-061-261000-
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-
124 PM CDT Tue May 25 2021

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

.DAY ONE...This Afternoon and Tonight

Scattered storms late this afternoon into the evening. A few
could be severe, mostly between 4 and 10 pm and generally along
and north of Interstate 90. Large hail and damaging winds are the
main threats.

.DAYS TWO THROUGH SEVEN...Wednesday through Monday

A few thunderstorms could occur Wednesday night through Thursday
night. Organized severe weather is not expected.

.SPOTTER INFORMATION STATEMENT...

Spotter activation may be needed late this afternoon into the
early evening.

.EMERGENCY MANAGEMENT COORDINATION...

No webinar is scheduled.

Rieck

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE LA CROSSE WI
636 PM CDT TUE MAY 25 2021

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

0633 PM     HAIL             BLACK RIVER FALLS       44.30N 90.85W
05/25/2021  E0.25 INCH       JACKSON            WI   TRAINED SPOTTER

&&

SHEA

PRELIMINARY LOCAL STORM REPORT...SUMMARY
NATIONAL WEATHER SERVICE LA CROSSE WI
651 PM CDT TUE MAY 25 2021

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

0328 PM     HAIL             3 WNW ZUMBRO FALLS      44.30N 92.47W
05/25/2021  E1.00 INCH       WABASHA            MN   PUBLIC

0334 PM     HAIL             2 NNE ZUMBRO FALLS      44.32N 92.41W
05/25/2021  E0.50 INCH       WABASHA            MN   PUBLIC

0351 PM     HAIL             5 NNW THEILMAN          44.35N 92.23W
05/25/2021  M0.88 INCH       WABASHA            MN   TRAINED SPOTTER

0405 PM     HAIL             2 N DUMFRIES            44.38N 92.12W
05/25/2021  M1.25 INCH       WABASHA            MN   AMATEUR RADIO

0406 PM     TSTM WND GST     6 NW ROCHESTER          44.08N 92.56W
05/25/2021  E40 MPH          OLMSTED            MN   BROADCAST MEDIA

0407 PM     HAIL             6 NNE ROCHESTER         44.10N 92.44W
05/25/2021  E0.25 INCH       OLMSTED            MN   EMERGENCY MNGR

0408 PM     HAIL             NELSON                  44.42N 92.00W
05/25/2021  M0.70 INCH       BUFFALO            WI   TRAINED SPOTTER

0426 PM     HAIL             JUMP RIVER              45.36N 90.80W
05/25/2021  M0.25 INCH       TAYLOR             WI   COCORAHS

0427 PM     HEAVY RAIN       NELSON                  44.42N 92.00W
05/25/2021  M1.00 INCH       BUFFALO            WI   TRAINED SPOTTER

0430 PM     HEAVY RAIN       NELSON                  44.43N 92.01W
05/25/2021  M1.00 INCH       BUFFALO            WI   TRAINED SPOTTER

0441 PM     TSTM WND DMG     COCHRANE                44.22N 91.83W
05/25/2021                   BUFFALO            WI   PUBLIC

0445 PM     HAIL             4 NW FOUNTAIN CITY      44.16N 91.75W
05/25/2021  M0.25 INCH       BUFFALO            WI   AMATEUR RADIO

0445 PM     TSTM WND DMG     NW BUFFALO              44.22N 91.87W
05/25/2021                   BUFFALO            WI   BROADCAST MEDIA

            TREES BLOWN DOWN.

0456 PM     TSTM WND GST     3 S ARCADIA             44.21N 91.49W
05/25/2021  E60 MPH          TREMPEALEAU        WI   TRAINED SPOTTER

            1 TO 2 INCH LIMBS DOWN. TORRENTIAL RAIN.

0457 PM     TSTM WND DMG     ARCADIA                 44.25N 91.49W
05/25/2021                   TREMPEALEAU        WI   BROADCAST MEDIA

            TREES DAMAGE AND SEMI TRAILERS FLIPPED.

0459 PM     TSTM WND DMG     ARCADIA                 44.25N 91.49W
05/25/2021                   TREMPEALEAU        WI   LAW ENFORCEMENT

            NUMEROUS TREES DOWN AROUND COUNTY, SOME ON
            HOMES AND POWER LINES. ONE MOBILE HOME
            FLIPPED.

0459 PM     TSTM WND GST     ARCADIA                 44.25N 91.49W
05/25/2021  E60 MPH          TREMPEALEAU        WI   TRAINED SPOTTER

0528 PM     TSTM WND DMG     5 NNE MERRILLAN         44.52N 90.80W
05/25/2021                   CLARK              WI   LAW ENFORCEMENT

            REPORTS OF TREES DOWN.

0530 PM     TSTM WND DMG     BLACK RIVER FALLS       44.30N 90.85W
05/25/2021                   JACKSON            WI   LAW ENFORCEMENT

            REPORTS OF TREES DOWN IN VARIOUS SPOTS
            AROUND THE COUNTY.

0535 PM     TSTM WND DMG     NEILLSVILLE             44.56N 90.59W
05/25/2021                   CLARK              WI   LAW ENFORCEMENT

            ISOLATED TREE DAMAGE REPORTED AROUND
            NEILLSVILLE AND TO THE SOUTH OF TOWN.

0549 PM     HAIL             4 S HATFIELD            44.36N 90.72W
05/25/2021  U0.50 INCH       JACKSON            WI   PUBLIC

            REPORT FROM MPING: HALF-INCH (0.50 IN.).

0550 PM     TSTM WND DMG     GRANTON                 44.59N 90.46W
05/25/2021                   CLARK              WI   911 CALL CENTER

0556 PM     HAIL             3 E LOYAL               44.74N 90.44W
05/25/2021  M0.50 INCH       CLARK              WI   TRAINED SPOTTER

0559 PM     TSTM WND DMG     7 S GRANTON             44.50N 90.48W
05/25/2021                   CLARK              WI   PUBLIC

            REPORT FROM MPING: 1-INCH TREE LIMBS BROKEN;
            SHINGLES BLOWN OFF.

0606 PM     TSTM WND DMG     6 SW LINDSEY            44.47N 90.36W
05/25/2021                   CLARK              WI   PUBLIC

            REPORT FROM MPING: 1-INCH TREE LIMBS BROKEN;
            SHINGLES BLOWN OFF.

0608 PM     TSTM WND DMG     6 S LINDSEY             44.46N 90.33W
05/25/2021                   CLARK              WI   PUBLIC

            REPORT FROM MPING: 1-INCH TREE LIMBS BROKEN;
            SHINGLES BLOWN OFF.

&&

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE LA CROSSE WI
659 PM CDT TUE MAY 25 2021

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

0457 PM     TSTM WND DMG     ARCADIA                 44.25N 91.49W
05/25/2021                   TREMPEALEAU        WI   EMERGENCY MNGR

            SEVERAL LIGHT POLES AT SPEEDWAY BLOWN DOWN. ABOUT A DOZEN
            TREES DOWN IN MEMORIAL PARK AND OTHER TREES BLOWN DOWN IN
            THE DOWNTOWN AREA. ONE MOBILE HOME WAS BLOWN OFF
            FOUNDATION ON NORTH SIDE OF TOWN. ESTIMATED STRAIGHT LINE
            WIND DAMAGE.

&&

SHEA

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE LA CROSSE WI
703 PM CDT TUE MAY 25 2021

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

0605 PM     TSTM WND DMG     4 S GRANTON             44.54N 90.46W
05/25/2021                   CLARK              WI   PUBLIC

&&

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE LA CROSSE WI
710 PM CDT TUE MAY 25 2021

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

0709 PM     HEAVY RAIN       1 WNW BLACK RIVER FALLS 44.31N 90.87W
05/25/2021  M1.50 INCH       JACKSON            WI   TRAINED SPOTTER

&&

Special Weather Statement
National Weather Service La Crosse WI
842 PM CDT Tue May 25 2021

IAZ010-260215-
Winneshiek-
842 PM CDT Tue May 25 2021

...A STRONG THUNDERSTORM WILL AFFECT CENTRAL WINNESHIEK COUNTY...

At 842 PM CDT, a strong thunderstorm was located near Decorah, moving
east at 45 mph.

Wind gusts to 40 mph and half inch hail are possible with this storm.

This storm will be near...
  Decorah around 850 PM CDT.

Other locations impacted by this storm include Nordness,
Highlandville, Burr Oak, Glenwood Church, Bluffton, Chimney Rock
Campground, Locust, Sattre, State Road 9 And 245th Street and County
Roads W 14 And A 34.

If outdoors, consider seeking shelter inside a building.

LAT...LON 4343 9208 4350 9161 4321 9161 4324 9208
TIME...MOT...LOC 0142Z 258DEG 41KT 4334 9188

Wetenkamp