Alert archive / Iowa / Severe Thunderstorm Warnings in 2026
Severe Thunderstorm Warning 182, NWS La Crosse, WI
NWS La Crosse, WI issued this severe thunderstorm warning at Aug 21, 2026, 3:01 AM CDT for Howard County, Winneshiek County, Iowa; Fillmore County, Minnesota. It was in force for 38 min. No storm report in the archive falls inside the area while it was in force.
The area
The outline as issued.
The facts
- Issued
- Aug 21, 2026, 3:01 AM CDT (08:01 UTC)
- Expired
- Aug 21, 2026, 3:39 AM CDT
- In force
- 38 min
- Issued by
- NWS La Crosse, WI
- Area
- Storm-based polygon
- Hail
- 1.0 in
- Wind
- 60.0 mph
Counties Howard County, IA, Winneshiek County, IA, Fillmore County, MN
The radar
The La Crosse radar (KARX), 86 km from the middle of the area, began a volume at 08:04 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.
Did it verify
Not verified. The Iowa Environmental Mesonet's Cow found no qualifying storm report inside this severe thunderstorm 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 nearest sounding before it
Minneapolis, MN (KMPX), launched 00:00Z, 8.0 hours before the alert went out and 190 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.
- Mixed-layer CAPE
- 1101 J/kg
- Mixed-layer CIN
- -20 J/kg
- Mixed-layer LCL
- 1018 m above ground
- 0-6 km bulk shear
- 39 kt
- 0-1 km storm-relative helicity
- 162 m²/s²
- 0-3 km storm-relative helicity
- 258 m²/s²
- Significant tornado parameter
- 0.6
- Supercell composite
- 5.2
The text
As transmitted.
359
WUUS53 KARX 210801
SVRARX
IAC089-191-MNC045-210900-
/O.NEW.KARX.SV.W.0182.260821T0801Z-260821T0900Z/
BULLETIN - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Warning
National Weather Service La Crosse WI
301 AM CDT Fri Aug 21 2026
The National Weather Service in La Crosse has issued a
* Severe Thunderstorm Warning for...
Northeastern Howard County in northeastern Iowa...
Northwestern Winneshiek County in northeastern Iowa...
Southern Fillmore County in southeastern Minnesota...
* Until 400 AM CDT.
* At 301 AM CDT, a severe thunderstorm was located near Le Roy, or 16
miles northwest of Cresco, moving east at 40 mph.
HAZARD...60 mph wind gusts and quarter size hail.
SOURCE...Radar indicated.
IMPACT...Hail damage to vehicles is expected. Expect wind damage
to roofs, siding, and trees.
* This severe thunderstorm will be near...
Lime Springs around 305 AM CDT.
Harmony around 325 AM CDT.
Canton around 330 AM CDT.
Mabel around 345 AM CDT.
Other locations impacted by this severe thunderstorm include Hesper,
York, Burr Oak, Locust, Chester, Granger, and Newburg.
PRECAUTIONARY/PREPAREDNESS ACTIONS...
For your protection move to an interior room on the lowest floor of a
building.
To report severe weather, contact your nearest law enforcement
agency. They will send your report to the National Weather Service
office in La Crosse.
&&
LAT...LON 4346 9245 4355 9245 4360 9173 4339 9173
TIME...MOT...LOC 0801Z 270DEG 34KT 4350 9238
HAIL THREAT...RADAR INDICATED
MAX HAIL SIZE...1.00 IN
WIND THREAT...RADAR INDICATED
MAX WIND GUST...60 MPH
$$
Ferguson3 follow-up statements
240
WWUS53 KARX 210817
SVSARX
Severe Weather Statement
National Weather Service La Crosse WI
317 AM CDT Fri Aug 21 2026
IAC089-191-MNC045-210900-
/O.CON.KARX.SV.W.0182.000000T0000Z-260821T0900Z/
Howard IA-Winneshiek IA-Fillmore MN-
317 AM CDT Fri Aug 21 2026
...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 400 AM CDT
FOR NORTHEASTERN HOWARD...NORTHWESTERN WINNESHIEK AND SOUTHEASTERN
FILLMORE COUNTIES...
At 317 AM CDT, a severe thunderstorm was located 7 miles northeast of
Lime Springs, or 11 miles southwest of Preston, moving east at 35
mph.
HAZARD...60 mph wind gusts and half dollar size hail.
SOURCE...Radar indicated.
IMPACT...Hail damage to vehicles is expected. Expect wind damage to
roofs, siding, and trees.
This severe storm will be near...
Harmony around 325 AM CDT.
Canton around 330 AM CDT.
Mabel around 345 AM CDT.
Other locations impacted by this severe thunderstorm include Granger,
Newburg, Hesper, York, Bristol, Burr Oak, and Lenora.
PRECAUTIONARY/PREPAREDNESS ACTIONS...
For your protection move to an interior room on the lowest floor of a
building.
To report severe weather contact your nearest law enforcement agency.
They will send your report to the National Weather Service office in
La Crosse.
&&
LAT...LON 4346 9228 4356 9229 4360 9173 4342 9173
TIME...MOT...LOC 0817Z 268DEG 31KT 4353 9217
HAIL THREAT...RADAR INDICATED
MAX HAIL SIZE...1.25 IN
WIND THREAT...RADAR INDICATED
MAX WIND GUST...60 MPH
$$
Ferguson929
WWUS53 KARX 210831
SVSARX
Severe Weather Statement
National Weather Service La Crosse WI
331 AM CDT Fri Aug 21 2026
IAC089-210841-
/O.CAN.KARX.SV.W.0182.000000T0000Z-260821T0900Z/
Howard IA-
331 AM CDT Fri Aug 21 2026
...THE SEVERE THUNDERSTORM WARNING FOR NORTHEASTERN HOWARD COUNTY IS
CANCELLED...
The severe thunderstorm which prompted the warning has moved out of
the warned area. Therefore, the warning has been cancelled.
&&
LAT...LON 4347 9208 4358 9208 4360 9173 4345 9173
TIME...MOT...LOC 0831Z 268DEG 27KT 4353 9203
$$
IAC191-MNC045-210900-
/O.CON.KARX.SV.W.0182.000000T0000Z-260821T0900Z/
Winneshiek IA-Fillmore MN-
331 AM CDT Fri Aug 21 2026
...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 400 AM CDT
FOR NORTHWESTERN WINNESHIEK AND SOUTHEASTERN FILLMORE COUNTIES...
At 331 AM CDT, a severe thunderstorm was located over Harmony, or 10
miles south of Preston, moving east at 30 mph.
HAZARD...60 mph wind gusts and quarter size hail.
SOURCE...Radar indicated.
IMPACT...Hail damage to vehicles is expected. Expect wind damage to
roofs, siding, and trees.
This severe storm will be near...
Harmony and Canton around 335 AM CDT.
Mabel around 350 AM CDT.
Other locations impacted by this severe thunderstorm include Lenora,
Newburg, Hesper, and Harvest Farm Campground.
PRECAUTIONARY/PREPAREDNESS ACTIONS...
For your protection move to an interior room on the lowest floor of a
building.
To report severe weather contact your nearest law enforcement agency.
They will send your report to the National Weather Service office in
La Crosse.
&&
LAT...LON 4347 9208 4358 9208 4360 9173 4345 9173
TIME...MOT...LOC 0831Z 268DEG 27KT 4353 9203
HAIL THREAT...RADAR INDICATED
MAX HAIL SIZE...1.00 IN
WIND THREAT...RADAR INDICATED
MAX WIND GUST...60 MPH
$$
Ferguson392 WWUS53 KARX 210839 SVSARX Severe Weather Statement National Weather Service La Crosse WI 339 AM CDT Fri Aug 21 2026 IAC191-MNC045-210849- /O.CAN.KARX.SV.W.0182.000000T0000Z-260821T0900Z/ Winneshiek IA-Fillmore MN- 339 AM CDT Fri Aug 21 2026 ...THE SEVERE THUNDERSTORM WARNING FOR NORTHWESTERN WINNESHIEK AND SOUTHEASTERN FILLMORE COUNTIES IS CANCELLED... The storm which prompted the warning has weakened below severe limits, and no longer poses an immediate threat to life or property. Therefore, the warning has been cancelled. To report severe weather, contact your nearest law enforcement agency. They will relay your report to the National Weather Service La Crosse. && LAT...LON 4347 9208 4358 9208 4360 9173 4345 9173 TIME...MOT...LOC 0837Z 270DEG 34KT 4353 9192 $$ Ferguson
What forecasters said that day
The local office's own words before this severe thunderstorm 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 severe thunderstorm warning went out at Aug 21, 12:20 AM CDT, 2 hours 41 minutes earlier. Its key messages:
- Scattered shower and storms move through the area through the morning and early afternoon with some potentially on the stronger side, especially for areas in southwest Wisconsin.
- Seasonal temperatures continue into next week with highs in the 70s to lower 80s.
- Dry weekend with the next potential round of storms coming Tuesday and Wednesday of next week.
Area forecast discussion, Aug 21, 12:20 AM CDT, 2 hours 41 minutes before
Area Forecast Discussion National Weather Service La Crosse WI 1220 AM CDT Fri Aug 21 2026 .KEY MESSAGES... - Scattered shower and storms move through the area through the morning and early afternoon with some potentially on the stronger side, especially for areas in southwest Wisconsin. - Seasonal temperatures continue into next week with highs in the 70s to lower 80s. - Dry weekend with the next potential round of storms coming Tuesday and Wednesday of next week. && .DISCUSSION... Issued at 1205 AM CDT Fri Aug 21 2026 Today: Storm Potential Invigorating upper level northwest flow is driving storm development upstream through central Minnesota overnight, focused along an enhanced area of low level convergence on Central to Northern Plains VWPs. A meager open perturbation well to the north over Lake Superior on GOES derived upper level wind plots has prevented storms spreading as far south as the local forecast area as subsequent supplementary forcing from the low level frontal boundary trails well behind, struggling to traverse the Missouri River Valley into west-central Minnesota. Eventual synoptic assistance from an additional perturbation crossing the International Border from Saskatchewan into Northern Dakota will drive said frontal boundary southeast through the Upper Mississippi River Valley. Ahead of a cold front that will push through the region this morning and afternoon, a few weak perturbations and a slight increase in the nocturnal LLJ will help to initiate some storms, as recent CAMs have supported, during the early morning hours. With limited instability and minimal shear and mid-level subsidence, these showers and storms should remain below severe limits, however small hail and gusty winds will be possible. Heading into the mid morning to early afternoon timeframe, the cold front will begin to enter our CWA. Dependent on diurnal timing and southeastern extent of this low level frontal boundary across the forecast area, these prefrontal storms will likely continue for some of the local forecast area primarily from northeast Iowa into southwest Wisconsin. While instability is expected to be ample, around 2000 to 2500 J/kg of MLCAPE, there will be minimal shear present. With the increase in instability though and the fact that any storms that due form along and just ahead of the cold front will be in their developing phase, a storm or two could have severe hail up to 1". The better severe ingredients remain in southeast Wisconsin and northern Illinois and back west into Nebraska and southern Iowa. All precipitation chances diminish by the early afternoon. Total rainfall from these storms could be over 1" in some locations as the 00Z HREF LPMM has some spots of over 1" along the I-94 corridor and in far southwest Wisconsin. Saturday - Midweek: Dry Early, Storms Return Tuesday Northwest flow returns to the region as a trough amplifies to our east and the ridge sets up to our west. This ridge decays as it moves eastward into early next week. With our region in between these two features, we look to be mostly dry and slightly cooler through the weekend until the ridge breaks down on Tuesday. High temperatures stay in the low 70s to low 80s from Saturday through Monday. Storm chances return Tuesday as a trough moves down from northern Minnesota. The latest GEFS and EPS have a widespread 60 to 90% chance for measurable storms. The exact timing and placement details of this rain will be hammered out as we get closer to the event. && .AVIATION /06Z TAFS THROUGH 06Z SATURDAY/... Issued at 1217 AM CDT Fri Aug 21 2026 Primary concern over the next 24 hours will be potential for TS over the next 12 hours as a cold front pushes southeast. TS is likely (60-80%) overnight northeast of a EAU-82C line but could (30%) extend to near LSE. Have retained PROB30 mention and adjusted timing compared to previous TAF cycle. Probability is too low to keep a mention at RST (20%). Otherwise winds will turn clockwise from out of the southwest to out of the northwest over the next 12 hours as well and continue to be out of the northwest at 10-15 knots Friday afternoon. && .ARX WATCHES/WARNINGS/ADVISORIES... WI...None. MN...None. IA...None. && DISCUSSION...Cecava/JAR AVIATION...Ferguson
Hazardous weather outlook, Aug 20, 12:41 PM CDT, 14 hours 20 minutes before
Hazardous Weather Outlook National Weather Service La Crosse WI 1241 PM CDT Thu Aug 20 2026 IAZ008>011-018-019-029-030-MNZ088-095-096-WIZ017-029-033-034-041- 042-212145- Mitchell-Howard-Winneshiek-Allamakee-Floyd-Chickasaw-Fayette- Clayton-Winona-Fillmore-Houston-Taylor-Clark-Trempealeau-Jackson- La Crosse-Monroe- 1241 PM CDT Thu Aug 20 2026 This Hazardous Weather Outlook is for portions of north central Iowa...northeast Iowa...southeast Minnesota...central Wisconsin... north central Wisconsin and west central Wisconsin. .DAY ONE...This Afternoon and Tonight The probability for widespread hazardous weather is low. .DAYS TWO THROUGH SEVEN...Friday through Wednesday The probability for widespread hazardous weather is low. .SPOTTER INFORMATION STATEMENT... No action needed. .EMERGENCY MANAGEMENT COORDINATION... No webinar is scheduled. WIZ043-044-053>055-061-212145- Juneau-Adams-Vernon-Crawford-Richland-Grant- 1241 PM CDT Thu Aug 20 2026 This Hazardous Weather Outlook is for portions of central Wisconsin and southwest Wisconsin. .DAY ONE...This Afternoon and Tonight No hazardous weather is expected at this time. .DAYS TWO THROUGH SEVEN...Friday through Wednesday A few strong thunderstorms may affect the area during the early afternoon hours on Friday. .SPOTTER INFORMATION STATEMENT... No action needed. .EMERGENCY MANAGEMENT COORDINATION... No webinar is scheduled. MNZ079-086-087-094-WIZ032-212145- Wabasha-Dodge-Olmsted-Mower-Buffalo- 1241 PM CDT Thu Aug 20 2026 This Hazardous Weather Outlook is for portions of southeast Minnesota and west central Wisconsin. .DAY ONE...This Afternoon and Tonight A few strong thunderstorms may affect the area late tonight. .DAYS TWO THROUGH SEVEN...Friday through Wednesday The probability for widespread hazardous weather is low. .SPOTTER INFORMATION STATEMENT... No action needed. .EMERGENCY MANAGEMENT COORDINATION... No webinar is scheduled.
In the hours before
Special weather statement, Aug 21, 2:33 AM CDT, 28 minutes before
Special Weather Statement
National Weather Service La Crosse WI
233 AM CDT Fri Aug 21 2026
IAZ008-009-018-019-MNZ094-095-210800-
Floyd IA-Chickasaw IA-Howard IA-Mitchell IA-Fillmore MN-Mower MN-
233 AM CDT Fri Aug 21 2026
...A STRONG THUNDERSTORM WILL IMPACT MITCHELL...WESTERN HOWARD...
NORTHERN FLOYD...NORTHWESTERN CHICKASAW...SOUTHEASTERN MOWER AND
SOUTHWESTERN FILLMORE COUNTIES THROUGH 300 AM CDT...
At 232 AM CDT, Doppler radar was tracking a strong thunderstorm near
Stacyville, or 15 miles north of Osage, moving east at 35 mph.
HAZARD...Wind gusts up to 50 mph and pea size hail.
SOURCE...Radar indicated.
IMPACT...Gusty winds could knock down tree limbs and blow around
unsecured objects. Minor hail damage to vegetation is
possible.
This strong thunderstorm will be near...
Le Roy around 250 AM CDT.
Other locations impacted by this storm include Meyer, Toeterville,
Rock Creek, Idlewilde State Park, Brownville, and Colwell County
Park.
PRECAUTIONARY/PREPAREDNESS ACTIONS...
If outdoors, consider seeking shelter inside a building.
&&
LAT...LON 4343 9302 4356 9282 4351 9219 4307 9255
4320 9303
TIME...MOT...LOC 0732Z 286DEG 30KT 4349 9273
MAX HAIL SIZE...0.25 IN
MAX WIND GUST...50 MPH
FergusonSpecial weather statement, Aug 21, 2:54 AM CDT, 7 minutes before
Special Weather Statement
National Weather Service La Crosse WI
254 AM CDT Fri Aug 21 2026
IAZ008-009-MNZ094-095-210830-
Howard IA-Mitchell IA-Fillmore MN-Mower MN-
254 AM CDT Fri Aug 21 2026
...A STRONG THUNDERSTORM WILL IMPACT NORTHEASTERN MITCHELL...NORTHERN
HOWARD...SOUTHEASTERN MOWER AND SOUTHWESTERN FILLMORE COUNTIES
THROUGH 330 AM CDT...
At 254 AM CDT, Doppler radar was tracking a strong thunderstorm over
Le Roy, or 21 miles northwest of Cresco, moving east at 40 mph.
HAZARD...Wind gusts of 50 to 55 mph and nickel size hail.
SOURCE...Radar indicated.
IMPACT...Gusty winds could knock down tree limbs and blow around
unsecured objects. Minor hail damage to vegetation is
possible.
This strong thunderstorm will be near...
Lime Springs around 305 AM CDT.
Other locations impacted by this storm include Lake Louise State
Park, Chester, Granger, York, Bonair, and Hayden Prairie.
PRECAUTIONARY/PREPAREDNESS ACTIONS...
If outdoors, consider seeking shelter inside a building.
&&
LAT...LON 4355 9259 4353 9206 4338 9215 4347 9262
TIME...MOT...LOC 0754Z 272DEG 34KT 4350 9250
MAX HAIL SIZE...0.88 IN
MAX WIND GUST...55 MPH
FergusonThe office that day
Everything else NWS La Crosse, WI issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Aug 21, 2:33 AM CDT | Special Weather Statement | ARX | Howard, Mitchell | 27 min |
| Aug 21, 2:54 AM CDT | Special Weather Statement | ARX | Howard | 36 min |
| Aug 21, 4:28 PM CDT | Severe Thunderstorm Warning | ARX | Clayton | 17 min |
Nearby
Severe Thunderstorm Warnings in Iowa, 2026Severe Thunderstorm Warnings in Minnesota, 2026Every severe thunderstorm warning 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; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.