Special Weather Statement, NWS La Crosse, WI

Area Forecast Discussion
National Weather Service La Crosse WI
230 PM CDT Mon May 31 2021

.SHORT TERM...(Tonight through Wednesday)
Issued at 230 PM CDT Mon May 31 2021

THIS AFTERNOON/EVENING - SCT STORMS: upper level shortwave trough
sinking southeast across MN at early afternoon, with cold front/sfc
trough on its leading edge. Rather weak convergence with the
boundary. Increasing mid/low level rates support SBCAPEs upwards of
1500 J/kg. Storms have started to fire along western portions of the
front, over south central MN. Convective trends in the meso models
have been rather volatile the past couple days, although all have
agreed at least a scattered line of convection would track southeast
across the area. Some of the latest HOPWRF captures current radar
trends well, developing the convection northeast along the boundary
through the afternoon, into the main CAPE pool. Will try and trend
rain chances this way. Cap eroding and/or convection developing a
top it, with Cloud Phase satellite imagery showing this quick
advancement northeast on the front with towering cu/storms. While
there is a decent amount of instability to work on, the wind shear
is meager at best. Roughly 20 kts 0-3 km, perhaps 30 kts in the 0-6
km layer. Not much to aid storm organization. Thinking is still for
pulse-type storms, capable of generally smaller hail with core drops
resulting in some enhanced wind gusts. Outflows could/will provide
another potential focus to kick off some storms. Severe risk looks
minimal and mostly hail-centric (but not ruling out - and still
holding across WI).

TUESDAY: what looked like a dry day may harbor some small rain/storm
chances, depending on how far south the sfc boundary makes it
tonight. Some indications in the meso models that this boundary will
continue to become more diffuse, but could lay up across southern
parts of the forecast area, and possess enough convergence (still
weak) that with progged MUCAPES of 500-1000 J/kg, could kick off a
few showers/storms for the late afternoon/early evening. The forcing
is awfully weak though, and perhaps result more in some aggravated
cu rather than rain makers. For now, will keep it dry...but keep an
eye on it.

WEDNESDAY - RAIN OR DRY? The main question here is whether a
shortwave trough slipping out of the central Rockies to across the
southern/central plains will interact with pieces of energy shifting
east/southeast across the northern plains. The EC has been
persistent in its suggestion that the southern trough stays south,
traipsing east across the mid mississippi river valley. Any ripples
in the north mostly hold there - no merging/phasing. NAM in the same
boat. Rain chances would hold north/south of the local area. The GFS
is a lot more active, especially with dropping various bits of
energy from southern Canada across the region. Fairly widespread
rain chances would result. That said, some trends over the last day
or two with keeping the main trough in the south farther south, ala
the EC/NAM. So, if the GFS is off with its abundance of bits of
shortwave energy in north, it too would lean toward dry. Think there
is probably enough potential to drop a ripple or two across the area
to continue some small chances Wed, but could be a lot more miss
than hit.

.LONG TERM...(Thursday through Monday)
Issued at 230 PM CDT Mon May 31 2021

TEMPS: heat still on the way with the GFS and EC staying the course
with pushing the west coast ridge eastward, across the Upper
Mississippi River Valley/Great Lakes by the weekend. Some hints in
the models that the ridge could stick around into the following
week, even amplify, as upper level energy digs into a trough over
the west coast. Weekend warmth could stick around for awhile. As for
how warm/hot, EC has remained very consistent with mid/upper 80s for
highs. All its ensemble members suggest above normal temps into
early next week, although top out at 90. So, not necessarily "hot",
but certainly on the warmer-side for early June. The GFS remains a
bit cooler, but still pushing the needle upward. NAEFS 850 mb temps
anomalies continue to run around +1 or so. So confidence high for
some summery warmth as we work toward the weekend, likely sticking
around for several days after.

PCPN: with an upper level ridge building in from the west coast for
the later half of the week, trends would favor dry until maybe
Sun/Mon when return flow/potential ripples in the flow could spark a
few showers/storms. No consensus here between the EC and GFS, and
the ridge could be strengthening rather than shifting east - favored
more by the EC. Meanwhile, the GFS is also suggesting that a bit of
shortwave energy could drop across the approaching ridge for Thu
night. Rain chances result. Most of the GEFS members agree. The EC,
conversely, has a much weaker feature with little/if any pcpn
production. Think this looks more reasonable at this time. All in
all, still looking like a mostly dry end to the week.

&&

.AVIATION...(For the 18Z TAFS through 18Z Tuesday afternoon)
Issued at 1238 PM CDT Mon May 31 2021

Main taf concern is potential for thunderstorms at taf sites this
afternoon into the early evening hours. A weak cold front will track
across the area this afternoon and evening. The combination of
daytime heating and weak moisture convergence along the front will
allow for the development of isolated to scattered
showers/thunderstorms. The lack of stronger lift and moisture
convergence will inhibit the coverage of the shower/thunderstorm
activity. This would result in lower chances of thunderstorms or
showers to impact the taf sites this afternoon and early evening.
Will continue trends with no mention of any showers/thunderstorms at
both RST/LSE taf sites. Another concern is the possibility of fog
development in river valleys tonight. Latest model guidance suggest
a strong inversion developing and with clear skies/light winds...fog
will develop in river valleys. How widespread the fog will be in the
Mississippi River valley and impact the LSE taf site is the main
issue. At this time...will leave mention out of the LSE taf site.

&&

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

SHORT TERM...Rieck
LONG TERM....Rieck
AVIATION.....DTJ

Hazardous Weather Outlook
National Weather Service La Crosse WI
1103 AM CDT Mon May 31 2021

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-
1103 AM CDT Mon May 31 2021

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

.DAY ONE...This afternoon and Tonight

Isolated to scattered thunderstorms will be possible between 3
and 9 pm. Stronger storms could produce small hail and gusty
winds.

.DAYS TWO THROUGH SEVEN...Tuesday through Sunday

There will be a chance of thunderstorms on Wednesday, Thursday,
and Sunday. At this time, organized severe weather is not
expected.

.SPOTTER INFORMATION STATEMENT...

No action needed.

.EMERGENCY MANAGEMENT COORDINATION...

No webinar is scheduled.

Rieck

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE LA CROSSE WI
350 PM CDT MON MAY 31 2021

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

0348 PM     HAIL             URNE                    44.50N 91.89W
05/31/2021  E0.88 INCH       BUFFALO            WI   PUBLIC

            DIME TO NICKEL.

&&

DB

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE LA CROSSE WI
354 PM CDT MON MAY 31 2021

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

0325 PM     HAIL             2 W WEST CONCORD        44.15N 92.94W
05/31/2021  E0.88 INCH       DODGE              MN   BROADCAST MEDIA

            PUBLIC VIA MEDIA. PHOTO VERIFICATION.

&&

DB

Special Weather Statement
National Weather Service La Crosse WI
357 PM CDT Mon May 31 2021

MNZ079-086>088-WIZ032-312145-
Wabasha-Olmsted-Dodge-Winona-Buffalo-
357 PM CDT Mon May 31 2021

...A LINE OF STRONG THUNDERSTORMS WILL AFFECT PORTIONS OF
NORTHWESTERN WINONA... OLMSTED...SOUTHEASTERN WABASHA...SOUTHEASTERN
DODGE AND CENTRAL BUFFALO COUNTIES...

At 355 PM CDT, radar indicated strong thunderstorms were located
along a line extending from near Modena to Elgin to near Kasson.
Movement was southeast at 15 mph.

Winds in excess of 40 mph and nickel size hail are possible with
these storms.

Locations impacted include...
Rochester, Dodge Center, Alma, Buffalo, Kasson, Byron, Plainview,
Eyota, Elgin, Buffalo City, Dover, Altura, Kellogg, Modena, Marion,
Rock Dell, Viola, Waumandee, Cochrane and Gilmanton.

This includes Interstate 90 in Minnesota between mile markers 208 and
225.

Frequent cloud to ground lightning is occurring with these storms.
Lightning can strike 10 miles away from a thunderstorm. Seek a safe
shelter inside a building or vehicle.

If you are on or near the Mississippi River, get out of the water
and move indoors or inside a vehicle. Remember, lightning can strike
out to 10 miles from the parent thunderstorm. If you can hear
thunder, you are close enough to be struck by lightning. Move to
safe shelter now! Do not be caught on the water in a thunderstorm.

Persons in campgrounds should consider seeking sturdy shelter until
these storms pass.

LAT...LON 4415 9232 4448 9178 4447 9153 4435 9153
      4402 9197 4383 9266 4383 9267 4402 9285
TIME...MOT...LOC 2055Z 304DEG 13KT 4441 9179 4413 9226 4398 9277

DAS

Special Weather Statement
National Weather Service La Crosse WI
447 PM CDT Mon May 31 2021

MNZ079-087-088-WIZ032-312230-
Wabasha-Olmsted-Winona-Buffalo-
447 PM CDT Mon May 31 2021

...A LINE OF STRONG THUNDERSTORMS WILL AFFECT WINONA...EAST CENTRAL
OLMSTED...SOUTHEASTERN WABASHA AND SOUTHEASTERN BUFFALO COUNTIES...

At 444 PM CDT, radar indicated a cluster of strong thunderstorms
located along a line extending from 9 miles northwest of Arcadia to
St.Charles. Movement was southeast at 15 mph.

Penny size hail is possible with these storms along with some
accumulation on roadways. This may produce some temporary slippery
conditions if traveling.

Locations impacted include...
Winona, Alma, Buffalo, Goodview, St. Charles, Eyota, Lewiston,
Buffalo City, Fountain City, Dover, Stockton, Rollingstone, Altura,
Dodge, Saratoga, Waumandee, Cochrane, West Newton, Fremont and Utica.

This includes Interstate 90 in Minnesota between mile markers 225 and
248.

Frequent cloud to ground lightning is occurring with this storm.
Lightning can strike 10 miles away from a thunderstorm. Seek a safe
shelter inside a building or vehicle.

Persons in campgrounds should consider seeking sturdy shelter until
these storms pass.

LAT...LON 4439 9181 4433 9153 4425 9153 4421 9160
      4418 9160 4417 9161 4414 9156 4411 9155
      4385 9188 4385 9210 4402 9231
TIME...MOT...LOC 2144Z 309DEG 16KT 4430 9167 4396 9209

DAS

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE LA CROSSE WI
449 PM CDT MON MAY 31 2021

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

0440 PM     HAIL             BUFFALO                 44.23N 91.86W
05/31/2021  E0.25 INCH       BUFFALO            WI   PUBLIC

            COVERING THE GROUND. NO WIND. 0.42 RAIN IN
            15 MINUTES.

&&

DB

Special Weather Statement
National Weather Service La Crosse WI
533 PM CDT Mon May 31 2021

MNZ079-088-WIZ017-029-032>034-041-312300-
Wabasha-Winona-Buffalo-Jackson-Taylor-Trempealeau-La Crosse-Clark-
533 PM CDT Mon May 31 2021

...A CLUSTER OF STRONG THUNDERSTORMS WILL AFFECT PORTIONS OF
SOUTHEAST MINNESOTA...WEST CENTRAL...AND NORTHCENTRAL WISCONSIN
THROUGH 6 PM...

At 531 PM CDT, radar indicated the leading edge of strong
thunderstorms were located along a line extending from 10 miles west
of Medford to near Winona. Movement was southeast at 15 to 20 mph.

Winds in excess of 30 mph and nickel size hail are possible with
the strongest storms.

Locations impacted include...
Winona, Medford, Arcadia, Mondovi, Wabasha, Whitehall, Alma, Buffalo,
Goodview, Plainview, Osseo, Thorp, Trempealeau, Galesville, Blair,
Independence, Strum, Greenwood, Buffalo City and Owen.

This includes the following highways...
 Interstate 94 between mile markers 88 and 110.
 Interstate 90 in Minnesota between mile markers 254 and 256, and
between mile markers 261 and 272.

Frequent cloud to ground lightning is occurring with this storm.
Lightning can strike 10 miles away from a thunderstorm. Seek a safe
shelter inside a building or vehicle.

Persons in campgrounds should consider seeking sturdy shelter until
these storms pass.

LAT...LON 4526 9005 4503 9027 4503 9031 4499 9031
      4385 9141 4430 9255 4436 9255 4437 9243
      4443 9243 4446 9238 4441 9208 4460 9200
      4460 9092 4528 9092 4530 9089
TIME...MOT...LOC 2231Z 317DEG 17KT 4519 9055 4396 9160

DAS