Tornadoes · United States · Iowa · 2026

EF1 tornado, Emmet County, Iowa, May 17, 2026

This EF1 tornado ran 1.1 miles across Emmet County on May 17, 2026, touching down at 9:29 PM CDT and reaching 25 yards wide. It killed nobody.

Preliminary. This is NWS DMX's damage survey, filed in the Damage Assessment Toolkit as Gruver. The rating, the path and the casualties are the survey's and can change while it is revised. The Storm Prediction Center compiles the official record of 2026 from these surveys and publishes it in the spring of 2027; this page moves to that tornado's permanent address when it does.

The rating scale

Tracks are drawn in the color of the rating. The Enhanced Fujita scale rates the damage rather than measuring the wind: the speeds are what that damage is taken to imply.

  1. EF065 to 85 mph

    Light damage. Surface peeled off some roofs, gutters and siding damaged, branches broken, shallow-rooted trees pushed over.

  2. EF186 to 110 mphthis tornado

    Moderate damage. Roofs badly stripped, mobile homes overturned or badly damaged, exterior doors lost, windows broken.

  3. EF2111 to 135 mph

    Considerable damage. Roofs torn off well-built houses, frame homes shifted on their foundations, mobile homes destroyed, large trees snapped or uprooted, cars lifted off the ground.

  4. EF3136 to 165 mph

    Severe damage. Whole stories of well-built houses destroyed, large buildings badly damaged, trains overturned, trees debarked, heavy cars lifted and thrown.

  5. EF4166 to 200 mph

    Devastating damage. Well-built houses leveled, structures with weak foundations moved some distance, cars thrown and large missiles generated.

  6. EF5over 200 mph

    Incredible damage. Strong frame houses swept off their foundations, car-sized missiles thrown more than 100 meters, steel-reinforced concrete badly damaged, high-rise buildings deformed.

  7. Unrated

    The survey recorded a tornado but could not put a number on it, most often because it crossed open country and damaged nothing a rating can be read from.

The survey

Rating, as surveyed
EF1, preliminary
Date
May 17, 2026
Touchdown
9:29 PM CDT (02:29 UTC)
Lifted
9:31 PM CDT (02:31 UTC)
On the ground
2 minutes
Path length
1.1 miles (1.7 km)
Path width
25 yards (23 m)
Deaths
0
Injuries
0
County
Emmet County
Touchdown point
43.400, -94.725
Lift-off point
43.413, -94.714
Highest wind the damage implies
100 mph
Surveyed by
NWS DMX
The office's name for it
Gruver
Survey last edited
August 18, 2026
Record number
None yet. SPC numbers 2026 in the spring of 2027.

What the survey found

Virtual survey with information from emergency management. 8 power poles broke and splintered. Video confirmed. 82 mph wind gusts recorded at Estherville Airport.

Written by NWS DMX in the NWS Damage Assessment Toolkit. A survey is revised as better evidence arrives.

The damage survey

1 damage points were recorded along this path by NWS DMX, in the Damage Assessment Toolkit the survey teams carry. The strongest indicator was rated EF1. The highest wind the damage implies is 100 mph.

  • Virtual survey with information from emergency management. 8 power poles broke and splintered. Video confirmed. 82 mph wind gusts recorded at Estherville Airport. Time estimated from radar.

Survey points are preliminary and are the raw material the published rating was built from. Source: NWS Damage Assessment Toolkit.

The warnings

30 minutes of warning. NWS DMX issued a tornado warning for this county at 01:59 UTC, 30 minutes before the tornado touched down, in force until 02:45 UTC.

The county was under a tornado watch, issued at 23:13 UTC and running to 04:04 UTC.

Issued (UTC)ExpiredProductOffice
23:13 UTC04:04 UTCTornado WatchDMX
01:59 UTC02:45 UTCTornado WarningDMX
02:15 UTC02:45 UTCTornado WarningDMX
02:28 UTC03:01 UTCSevere Thunderstorm WarningDMX
02:30 UTC02:52 UTCTornado WarningDMX

Every warning and watch covering the touchdown point that day, from the Iowa Environmental Mesonet's archive of National Weather Service products. Lead time is measured from the issue of the warning in force to the touchdown time in the database, both of which were recorded to the minute by different people.

The forecast that day

The Storm Prediction Center had this point in a Enhanced Risk, with a 0.10 chance of a tornado within 25 miles, in the hatched area where significant tornadoes were expected. The outlook in force was issued at 01:07 UTC.

SPC's Day 1 convective outlook as it stood when the tornado began, read at the touchdown point. The same archive is on the radar archive.

The air that afternoon

The radiosonde launches on either side of the tornado, from the nearest station that was launching then, drawn and analyzed the way Storm Lab does: the same diagram, the same parcel and shear definitions SPC's mesoanalysis uses.

Minneapolis, MN (KMPX), 00:00Z

2.5 hours before the tornado, 184 km from the path. May 18, 2026.

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 lifted from the surface. Mixed-layer CAPE 0 joules per kilogram, CIN -8890, lifted condensation level 1101 meters above ground. Wind barbs in knots down the right edge.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. The warm shading is its CAPE, the cool shading the inhibition it has to break through.
HodographHodograph, Minneapolis, MN at 00:00Z on 2026-05-18The wind through the lowest 10 kilometers as a curve, rings every 10 meters per second labeled in knots. Zero to 1 km storm-relative helicity 154 square meters per square second, 0 to 6 km bulk shear 42 knots.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. RM and LM are the right and left moving storms Bunkers' method gives; the shaded area is the 0 to 1 km storm-relative helicity.
Mixed-layer CAPE
0 J/kg
Mixed-layer CIN
-8890 J/kg
Surface CAPE
0 J/kg
Mixed-layer LCL
1101 m above ground
0-6 km bulk shear
42 kt
0-1 km bulk shear
14 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
0-3 km lapse rate
5.1 K/km

Open this sounding in Storm Lab

Minneapolis, MN (KMPX), 12:00Z

9.5 hours after it, 184 km from the path. May 18, 2026.

Skew-T log-pSkew-T log-p diagram, Minneapolis, MN at 12:00Z on 2026-05-18Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel lifted from the surface. Mixed-layer CAPE 0 joules per kilogram, CIN -7988, lifted condensation level 882 meters above ground. Wind barbs in knots down the right edge.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. The warm shading is its CAPE, the cool shading the inhibition it has to break through.
HodographHodograph, Minneapolis, MN at 12:00Z on 2026-05-18The wind through the lowest 10 kilometers as a curve, rings every 10 meters per second labeled in knots. Zero to 1 km storm-relative helicity 149 square meters per square second, 0 to 6 km bulk shear 32 knots.1939587897Sfc1 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. RM and LM are the right and left moving storms Bunkers' method gives; the shaded area is the 0 to 1 km storm-relative helicity.
Mixed-layer CAPE
0 J/kg
Mixed-layer CIN
-7988 J/kg
Surface CAPE
0 J/kg
Mixed-layer LCL
882 m above ground
0-6 km bulk shear
32 kt
0-1 km bulk shear
19 kt
0-1 km storm-relative helicity
149 m²/s²
0-3 km storm-relative helicity
175 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0
0-3 km lapse rate
3.4 K/km

Open this sounding in Storm Lab

The surface observations

Estherville (EST), 2 km from the path, in the two hours either side.

Time (UTC)Temp (°F)Dew point (°F)WindGust (kt)Pressure (mb)Weather
00:29 UTC7666170° 17 kt241000.7
00:30 UTC 1000.7
00:35 UTC 1000.7
00:40 UTC 1000.3
00:45 UTC 1001.4
00:49 UTC7562300° 15 kt231001.7
00:50 UTC 1001.7
00:52 UTC7157290° 11 kt231001.7
00:55 UTC300° 7 kt1001.7
01:00 UTC260° 12 kt1001.7
01:05 UTC 1001.7
01:10 UTC330° 18 kt1001.4
01:15 UTC 1001.7
01:20 UTC320° 14 kt1001.7
01:25 UTC330° 13 kt1001.4
01:30 UTC350° 10 kt1001
01:35 UTC6760360° 9 kt1001VCTS
01:35 UTC360° 9 kt1001
01:40 UTC360° 12 kt1000.7
01:45 UTC20° 7 kt1001
01:49 UTC676140° 11 kt1000.7VCTS
01:50 UTC40° 13 kt1000.7
01:55 UTC 1000.7
01:59 UTC666230° 12 kt1000.7
02:00 UTC40° 12 kt1000.7
02:05 UTC70° 9 kt1000.3
02:10 UTC 1000.3
02:15 UTC 19 kt
02:16 UTC666060° 18 kt27999.3VCTS
02:20 UTC50° 20 kt28998
02:21 UTC666050° 23 kt30997.6TS
02:25 UTC 26
02:30 UTC6561 1002.7-TSRA BR
02:30 UTC 1002.7-RA BR
02:32 UTC6360 1002.4+TSRA BR
02:35 UTC 321001.7+RA FG
02:38 UTC5958280° 51 kt651001+TSRA FG SQ
02:40 UTC 49 kt60+RA FG SQ
02:41 UTC5958280° 47 kt711001+TSRA FG SQ

From the Iowa Environmental Mesonet's archive of airport observations.

The radar

The Sioux Falls radar (KFSD), 163 km away, was scanning. The volume nearest the touchdown began at 02:29 UTC.

Open the radar archive at this moment, over the track

Reflectivity and velocity, decoded from the Level II archive in the browser. Volumes take a few seconds to open the first time.

What was reported nearby

Local storm reports within 60 km of the path, in the three hours either side.

Time (UTC)ReportWhereCountyRemark
01:49 UTCTSTM WND DMGGreenvilleClay, IADamage to the Greenville grain elevator. Branches and power lines also downed. Time estimated from radar.
01:49 UTCTSTM WND DMGGreenvilleClay, IADamage to the Greenville grain elevator. Branches and power lines also downed. Time estimated from radar.
02:08 UTCTORNADO2 Nw TerrilDickinson, IAViewed on social media.
02:08 UTCTORNADO2 Nw TerrilDickinson, IAViewed on social media.
02:12 UTCTSTM WND DMG4 W West BendPalo Alto, IADaily CoCoRaHS observer notes from IA-PA-5 stated there was damage to a machine shed 1 mile ESE of their location, which is the location of this report. Time estimated from radar.
02:12 UTCTSTM WND GST 581 S Arnolds ParkDickinson, IAVia personal weather station.
02:12 UTCTSTM WND GST 581 S Arnolds ParkDickinson, IAVia personal weather station.
02:14 UTCTORNADOGraettingerPalo Alto, IAReports of power pole and tree damage in town. Time estimated by radar.
02:23 UTCTSTM WND DMG1 N EsthervilleEmmet, IA2-3 inch diameter limbs down. Time estimated via radar.
02:28 UTCTORNADO3 Ssw ArmstrongEmmet, IAConfirmed tornado estimated via webcam.
02:33 UTCTSTM WND DMGAlgonaKossuth, IADelayed report - received photo on social media of large tree limb on home.
02:33 UTCTSTM WND DMGLone RockKossuth, IATree uprooted near Lone Rock. Delayed report from broadcast media, time estimated by radar.
02:39 UTCTSTM WND DMGAlgonaKossuth, IADowned tree limb on home. Time estimated via radar.
02:41 UTCTSTM WND GST 822 Wnw GruverEmmet, IAASOS station KEST Estherville Airport.
02:42 UTCTSTM WND DMG4 Wnw LedyardKossuth, IACouple of trees down. Time estimated via radar.
03:11 UTCTSTM WND GST 676 Ne LedyardKossuth, IA

From the Iowa Environmental Mesonet's archive of National Weather Service local storm reports.

This ground now

The live radar over the trackEvery 2026 tornado in IowaEvery tornado in Iowa since 1950Warnings in force in Iowa nowThe forecast where you are

The other tornadoes of May 17, 2026

46 more have been surveyed in the United States that day, so far.

DateTimeRatingWherePath (mi)Width (yd)DeathsInjuriesDamage
May 173:17 PM EDTEF0Lee, FL0.125
May 173:25 PM EDTEF0Lee, FL2.1150
May 173:35 PM EDTEF0Lee, FL0.550
May 174:05 PM CDTUnratedTurner, SD0.70
May 175:04 PM CDTEF3Howard, NE6.1350
May 175:23 PM CDTEF0Merrick, NE1.330
May 175:58 PM CDTUnratedNobles, MN1.325
May 176:15 PM CDTUnratedNobles, MN0.620
May 176:42 PM CDTEF1Thayer, NE4.3200$10
May 177:11 PM CDTEF0Ida, IA0.560
May 177:12 PM CDTUnratedMartin, MN0.30
May 177:19 PM CDTEF1Thurston, NE1.9300
May 177:31 PM CDTEF0Woodbury, IA2.575
May 177:37 PM CDTEF1Woodbury, IA3.9100
May 177:55 PM CDTEF1Saunders, NE0.840
May 178:07 PM CDTUnratedPlymouth, IA0.70
May 178:10 PM CDTUnratedCherokee, IA0.40
May 178:11 PM CDTUnratedCherokee, IA0.90
May 178:15 PM CDTUnratedCherokee, IA0.80
May 178:25 PM CDTUnratedCherokee, IA0.90
May 178:31 PM CDTUnratedClay, IA1.20
May 178:42 PM CDTUnratedBuena Vista, IA2.275
May 178:45 PM CDTEF1Cass, NE0.8100
May 178:48 PM CDTUnratedClay, IA0.920
May 178:53 PM CDTUnratedClay, IA4.075
May 179:01 PM CDTEF1Calhoun, IA4.250
May 179:03 PM CDTEF1Palo Alto, IA3.525
May 179:05 PM CDTEF1Pocahontas, IA1.125
May 179:06 PM CDTEF0Clay, IA1.230
May 179:08 PM CDTUnratedDickinson, IA0.625
May 179:10 PM CDTEF1Palo Alto, IA3.70
May 179:10 PM CDTUnratedDickinson, IA1.545
May 179:10 PM CDTEF1Calhoun, IA0.230
May 179:12 PM CDTUnratedEmmet, IA1.330
May 179:17 PM CDTEF0Palo Alto, IA0.825
May 179:19 PM CDTEF0Palo Alto, IA2.725
May 179:20 PM CDTEF0Palo Alto, IA1.120
May 179:24 PM CDTEF0Webster, IA4.750
May 179:41 PM CDTEF1Kossuth, IA10.20
May 1710:07 PM CDTEF1Cerro Gordo, IA0.240
May 1710:10 PM CDTEF1Worth, IA9.10
May 1710:13 PM CDTEF1Cerro Gordo, IA7.040
May 1710:14 PM CDTEF1Freeborn, MN1.20
May 1710:15 PM CDTUnratedCerro Gordo, IA2.40
May 1710:18 PM CDTUnratedCerro Gordo, IA2.60
May 1710:27 PM CDTEF1Freeborn, MN0.40

What this means

Ratings are the survey's, read off the damage rather than measured; the rating scale is above. A survey can be revised, so the rating, the path and the casualties can all still change.

Sources

NWS Damage Assessment Toolkit, the record the survey teams file from the damage, and NOAA Storm Prediction Center storm reports. Neither is the official database for 2026, which SPC publishes in the spring of 2027.