Alert archive / Iowa / Tornado Warnings in 2026

Tornado Warning 40, NWS La Crosse, WI

May 17, 2026Floyd County, Mitchell County, Iowa

NWS La Crosse, WI issued this tornado warning at May 17, 2026, 10:24 PM CDT for Floyd County, Mitchell County, Iowa. It was in force for 51 min. 1 report came from inside the area while it was in force.

The area

The outline as issued, with what was reported inside it.

The facts

Issued
May 17, 2026, 10:24 PM CDT (03:24 UTC)
Expired
May 17, 2026, 11:15 PM CDT
In force
51 min
Issued by
NWS La Crosse, WI
Area
Storm-based polygon
Tornado
Radar indicated
Hail
0.0 in

Counties Floyd County, IA, Mitchell County, IA

The radar

The La Crosse radar (KARX), 151 km from the middle of the area, began a volume at 03:23 UTC, the scan nearest the moment this went out.

Open the radar archive at this moment

The archived warnings, watches and discussions in force at that minute are drawn over the scan, this one among them.

What was reported inside it

TimeReportWhereRemark
May 17, 10:34 PM CDTTSTM WND GST 70Nora Springs, IA

Local storm reports filed while the alert was in force, from inside its polygon or its counties.

Did it verify

Not verified. The Iowa Environmental Mesonet's Cow found no qualifying storm report inside this tornado warning while it was in force. That is not proof nothing happened: reports are thin where few people live.

Cow counts a report within 15 km of the polygon while the warning was in force: a tornado for a tornado warning; hail of 1 inch or more, a gust of 58 mph or more or wind damage for a severe thunderstorm warning; a flash flood report for a flash flood warning.

The watch it was issued in

The SPC watch in force over the same counties when this warning went out.

IssuedProductOfficeLasted
May 17, 6:12 PM CDTTornado WatchSPC6 hr

The nearest sounding before it

Minneapolis, MN (KMPX), launched 00:00Z, 3.4 hours before the alert went out and 197 km from the middle of its area. This is the routine balloon launch nearest before it, the air the forecaster had in hand, not a measurement taken for the alert.

Skew-T log-pSkew-T log-p diagram, Minneapolis, MN at 00:00Z on 2026-05-18Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 0 joules per kilogram.LCL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Minneapolis, MN at 00:00Z on 2026-05-18The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 154 square meters per square second.19395878Sfc1 km3 km6 km9 kmRMLM
The wind turning with height, colored by layer: ground to 1 km, 1 to 3 km, 3 to 6 km, 6 to 10 km.
Mixed-layer CAPE
0 J/kg
Mixed-layer CIN
No buoyant parcel
Mixed-layer LCL
1101 m above ground
0-6 km bulk shear
42 kt
0-1 km storm-relative helicity
154 m²/s²
0-3 km storm-relative helicity
237 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

The text

As transmitted.

419 
WFUS53 KARX 180324
TORARX
IAC067-131-180415-
/O.NEW.KARX.TO.W.0040.260518T0324Z-260518T0415Z/

BULLETIN - EAS ACTIVATION REQUESTED
Tornado Warning
National Weather Service La Crosse WI
1024 PM CDT Sun May 17 2026

The National Weather Service in La Crosse has issued a

* Tornado Warning for...
  Southeastern Mitchell County in north central Iowa...
  Northern Floyd County in north central Iowa...

* Until 1115 PM CDT.

* At 1023 PM CDT, a severe thunderstorm capable of producing a
  tornado was located near Mason City, moving east at 55 mph.

  HAZARD...Tornado.

  SOURCE...Radar indicated rotation.

  IMPACT...Flying debris will be dangerous to those caught without 
           shelter. Mobile homes will be damaged or destroyed. 
           Damage to roofs, windows, and vehicles will occur.  Tree 
           damage is likely.

* This dangerous storm will be near...
  Rudd around 1035 PM CDT.

Other locations impacted by this tornadic thunderstorm include
Colwell County Park, Orchard, New Haven, Idlewilde State Park,
Howardville, County Roads 147 And T 34, and County Roads B 20 And T
26.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Heavy rainfall may hide this tornado. Do not wait to see or hear the
tornado. TAKE COVER NOW!

&&

LAT...LON 4321 9302 4331 9256 4312 9256 4300 9302
TIME...MOT...LOC 0323Z 247DEG 48KT 4308 9317 

TORNADO...RADAR INDICATED
MAX HAIL SIZE...0.00 IN

$$

Baumgardt
3 follow-up statements
483 
WWUS53 KARX 180336
SVSARX

Severe Weather Statement
National Weather Service La Crosse WI
1036 PM CDT Sun May 17 2026

IAC067-131-180415-
/O.CON.KARX.TO.W.0040.000000T0000Z-260518T0415Z/
Mitchell IA-Floyd IA-
1036 PM CDT Sun May 17 2026

...A TORNADO WARNING REMAINS IN EFFECT UNTIL 1115 PM CDT FOR
SOUTHEASTERN MITCHELL AND NORTHERN FLOYD COUNTIES...

At 1035 PM CDT, a severe thunderstorm capable of producing a tornado
was located over Nora Springs, or 10 miles east of Mason City, moving
northeast at 55 mph.

HAZARD...Tornado.

SOURCE...Radar indicated rotation. This circulation produced a 
         tornado near Rockwell in the last 30 minutes. 

IMPACT...Flying debris will be dangerous to those caught without 
         shelter. Mobile homes will be damaged or destroyed. Damage 
         to roofs, windows, and vehicles will occur.  Tree damage is 
         likely.

This dangerous storm will be near...
  Rudd around 1040 PM CDT.

Other locations impacted by this tornadic thunderstorm include
Colwell County Park, Orchard, New Haven, Idlewilde State Park,
Howardville, County Roads 147 And T 34, and County Roads B 20 And T
26.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Heavy rainfall may hide this tornado. Do not wait to see or hear the
tornado. TAKE COVER NOW!

&&

LAT...LON 4321 9302 4331 9256 4312 9256 4300 9302
TIME...MOT...LOC 0335Z 243DEG 46KT 4315 9300 

TORNADO...RADAR INDICATED
MAX HAIL SIZE...0.00 IN

$$

Baumgardt
184 
WWUS53 KARX 180356
SVSARX

Severe Weather Statement
National Weather Service La Crosse WI
1056 PM CDT Sun May 17 2026

IAC067-131-180415-
/O.CON.KARX.TO.W.0040.000000T0000Z-260518T0415Z/
Mitchell IA-Floyd IA-
1056 PM CDT Sun May 17 2026

...A TORNADO WARNING REMAINS IN EFFECT UNTIL 1115 PM CDT FOR
SOUTHEASTERN MITCHELL AND NORTHEASTERN FLOYD COUNTIES...

At 1055 PM CDT, a severe thunderstorm capable of producing a tornado
was located 8 miles east of Osage, moving east at 50 mph.

HAZARD...Tornado.

SOURCE...Radar indicated rotation.

IMPACT...Flying debris will be dangerous to those caught without 
         shelter. Mobile homes will be damaged or destroyed. Damage 
         to roofs, windows, and vehicles will occur.  Tree damage is 
         likely.

This tornadic thunderstorm will remain over mainly rural areas of
southeastern Mitchell and northeastern Floyd Counties, including the
following locations... Colwell County Park, New Haven, Idlewilde
State Park, Howardville, Colwell, County Roads 17 And T 72, and Floyd
Crossing.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Heavy rainfall may hide this tornado. Do not wait to see or hear the
tornado. TAKE COVER NOW!

&&

LAT...LON 4326 9277 4331 9256 4312 9256 4307 9276
TIME...MOT...LOC 0355Z 249DEG 45KT 4325 9266 

TORNADO...RADAR INDICATED
MAX HAIL SIZE...0.00 IN

$$

Baumgardt
729 
WWUS53 KARX 180409
SVSARX

Severe Weather Statement
National Weather Service La Crosse WI
1109 PM CDT Sun May 17 2026

IAC067-131-180418-
/O.EXP.KARX.TO.W.0040.000000T0000Z-260518T0415Z/
Mitchell IA-Floyd IA-
1109 PM CDT Sun May 17 2026

...THE TORNADO WARNING FOR SOUTHEASTERN MITCHELL AND NORTHEASTERN
FLOYD COUNTIES WILL EXPIRE AT 1115 PM CDT...

The storm which prompted the warning has moved out of the area.
Therefore, the warning will be allowed to expire.

A Tornado Watch remains in effect until 100 AM CDT for north central
Iowa.

&&

LAT...LON 4326 9277 4331 9256 4312 9256 4307 9276
TIME...MOT...LOC 0408Z 247DEG 48KT 4331 9245 

$$

Baumgardt

What forecasters said that day

The local office's own words before this tornado warning went out, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.

NWS La Crosse, WI wrote its last area forecast discussion before this tornado warning went out at May 17, 8:19 PM CDT, 2 hours 5 minutes earlier. Its key messages:

  • Severe weather possible between 7 PM and 1 AM tonight. All hazards are possible mainly west of the Mississippi River.
  • Another round of severe weather possible on Monday night between 9 PM and 4 AM. The main threat will be damaging winds. With isolated threats of hail and maybe a few QLCS tornadoes.
Area forecast discussion, May 17, 8:19 PM CDT, 2 hours 5 minutes before
Area Forecast Discussion
National Weather Service La Crosse WI
819 PM CDT Sun May 17 2026

.KEY MESSAGES...

- Severe weather possible between 7 PM and 1 AM tonight. All
  hazards are possible mainly west of the Mississippi River.

- Another round of severe weather possible on Monday night
  between 9 PM and 4 AM. The main threat will be damaging winds.
  With isolated threats of hail and maybe a few QLCS tornadoes.

&&

.UPDATE...
Issued at 805 PM CDT Sun May 17 2026

Ongoing non-severe scattered storms across the local area are
inhibiting northward progression of warm front seen through
north-central Iowa on surface observations this evening, keeping
local severe threat conditional, i.e., lower overall confidence.
Intensification of the low level jet, 45 kt south wind on DMX
VWP, suggests a northern shift in warm front surging instability
farther north in the next 1-2 hours. Therefore, initial threat
of surface based, semi-discrete storm mode remains a low
confidence scenario to remain cognizant of until the eventual
MCS on radar imagery quickly shifting east through central
Minnesota arrives in 3+ hours. While main threat with this line
will be damaging winds, should the warm front reach farther
north, a QLCS tornado threat would exist primarily along the
frontal boundary. Therefore, the ongoing Tornado Watch may
require a switch to Severe Thunderstorm Watch.

&&

.DISCUSSION...
Issued at 1257 PM CDT Sun May 17 2026

This Afternoon

The remnant MCV which brought rain mainly south of Interstate 94
will continue to move northeast away from the area this afternoon.
As it does, the showers and isolated storms currently along
Interstates 90 and 94 will move east northeast away from the area.
Additional rainfall amounts will be up to a half inch. As a warm
front gradually lifts northward, temperatures along and south of
Interstate 94 will warm into the 60s and lower 70s, and into 60s
north of this Interstate. This will result in surface-based CAPES
climbing into the 1000 to 2500 J/kg along and south of Interstate 90
by 7 pm.

Tonight

Late this afternoon and evening, 2-3K J/kg CAPES will develop ahead
of a squall line moving east across eastern South Dakota, eastern
Nebraska, northern Iowa, and southern Minnesota. with 0-6 km
shear approaching 40 knots, there could potentially be some
supercells located along the line (these would likely stay
west of the Upper Mississippi River Vally) and along the warm
front near the Minnesota and Iowa boarder. In addition to the
deep shear, there is 200-300 EHI along the Minnesota and Iowa
boarder and downdraft CAPEs up to 1K J/kg. The discrete
supercells ahead of the squall line would be capable of
producing wet microbursts, large hail, and isolated tornadoes
between 7 PM and 10 PM in southeast Minnesota and northeast
Iowa. The threat will then shift to more damaging winds and
maybe a few QLCS tornadoes as the squall line moves into
southeast Minnesota and northeast Iowa between 10 PM and 11 PM.
This line will then gradually weaken as the instability wanes.
The severe weather threat will likely wane by 1 AM Monday.

Monday night

A cold front will move east through the area. There will be 1-2K
J/kg CAPES ahead of this front. With much of the deep (0-6 km) shear
located post frontal, not anticipating any supercells. As a result,
if there is severe weather, it would be located along the cold front
as a squall line. The primary threat would be damaging winds with
secondary threats as hail and QLCS tornadoes. Timing looks to be
rather similar tonight with the squall line moving into northeast
Iowa and southeast Minnesota between 9 PM and 10 PM. It will exit
the area between 2 AM and 4 AM. By this time, the winds will likely
be sub-severe.

Friday into Saturday

A shortwave trough will move east through the area. This will result
in another round of showers and isolated storms. With CAPES less
than 250 J/kg and 0-3 km and 0-6 km shear less than 25 knots, not
anticipating any organized severe weather at this time.

&&

.AVIATION /00Z TAFS THROUGH 00Z TUESDAY/...
Issued at 636 PM CDT Sun May 17 2026

MVFR to IFR conditions currently present across the region with
some isolated instances of LIFR along and south of the I-90
corridor. Low clouds are expected to linger for most areas
through later tonight with some low precip chances. The main
chance for storms looks to push east into the region late this
evening - likely between 04-08Z for the terminals. The main
threat with this line of storms will be strong winds and heavy
rainfall so have continued with the TEMPO groups that bring
stronger winds in for a short time period. Lower rain chances
will continue into tomorrow morning behind the line of storms
with most locations lifting back to VFR CIGs through the
morning. Some lower MVFR/IFR CIGs may linger across portions of
SE Minnesota and WC Wisconsin so have kept them at the KRST
terminal through the end of the period.

&&

.HYDROLOGY...
Issued at 106 AM CDT Sun May 17 2026

One to two inch totals are still forecast across the area, with
areas further west more favored for the 2 inch totals. This will
likely not cause river flooding, only within bank rises.

&&

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

&&

UPDATE...JAR
DISCUSSION...Boyne
AVIATION...Barendse
HYDROLOGY...Baumgardt
Hazardous weather outlook, May 17, 1:29 PM CDT, 8 hours 55 minutes before
Hazardous Weather Outlook
National Weather Service La Crosse WI
129 PM CDT Sun May 17 2026

IAZ008>011-018-019-029-030-MNZ079-086>088-094>096-WIZ032>034-041-
181100-
Mitchell-Howard-Winneshiek-Allamakee-Floyd-Chickasaw-Fayette-
Clayton-Wabasha-Dodge-Olmsted-Winona-Mower-Fillmore-Houston-
Buffalo-Trempealeau-Jackson-La Crosse-
129 PM CDT Sun May 17 2026

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

.DAY ONE...This Afternoon and Tonight

Scattered severe storms are possible later this evening and
early overnight with damaging wind as the main threat as a line
of storms progresses from west to east.

.DAYS TWO THROUGH SEVEN...Monday through Saturday

Scattered severe storms possible Monday evening and overnight
with damaging wind the main threat.

.SPOTTER INFORMATION STATEMENT...

Severe storm reports would be greatly appreciated.

.EMERGENCY MANAGEMENT COORDINATION...

No webinar is scheduled.

WIZ017-029-042>044-053>055-061-181100-
Taylor-Clark-Monroe-Juneau-Adams-Vernon-Crawford-Richland-Grant-
129 PM CDT Sun May 17 2026

This Hazardous Weather Outlook is for portions of central
Wisconsin...north central Wisconsin...southwest Wisconsin and
west central Wisconsin.

.DAY ONE...This Afternoon and Tonight

Scattered strong storms are possible overnight with wind gusts as
high as 45 mph as a line of storms progresses from west to east.

.DAYS TWO THROUGH SEVEN...Monday through Saturday

Scattered severe storms possible late Monday evening and
overnight with damaging wind as the main threat.

.SPOTTER INFORMATION STATEMENT...

Severe storm reports would be greatly appreciated.

.EMERGENCY MANAGEMENT COORDINATION...

No webinar is scheduled.

Boyne

The office that day

Everything else NWS La Crosse, WI issued on the same UTC day.

IssuedProductOfficeCountiesLasted
May 17, 10:09 PM CDTSevere Thunderstorm WarningARXFloyd, Mitchell66 min
May 17, 10:13 PM CDTTornado WarningARXMitchell62 min
May 17, 10:49 PM CDTSevere Thunderstorm WarningARXChickasaw, Howard56 min
May 17, 10:54 PM CDTTornado WarningARXChickasaw, Howard51 min
May 17, 11:40 PM CDTSevere Thunderstorm WarningARXWinneshiek28 min
May 18, 12:07 AM CDTSpecial Weather StatementARXAllamakee38 min

Nearby

Tornado Warnings in Iowa, 2026Every tornado warning in 2026Tornadoes in 2026

Sources

The product and its follow-ups from the Iowa Environmental Mesonet's archive of National Weather Service and Storm Prediction Center text; local storm reports from the same archive; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.