Unrated tornado, Royal, Iowa, May 17, 2026

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 mph

   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. Unratedthis tornado

   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.

Rating, as surveyed

Unrated, preliminary

Date

May 17, 2026

Touchdown

8:31 PM CDT (01:31 UTC)

Lifted

8:33 PM CDT (01:33 UTC)

On the ground

2 minutes

Path length

1.2 miles (1.9 km)

Path width

0 yards (0 m)

Deaths

0

Injuries

0

County

Clay County

Touchdown point

43.040, -95.380

Lift-off point

43.044, -95.357

Surveyed by

NWS FSD

The office's name for it

RoyalSW

Survey last edited

July 31, 2026

Record number

None yet. SPC numbers 2026 in the spring of 2027.

Approximate track from video evidence of brief touchdown provided by county Emergency Manager.

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

An approaching mid-level disturbance broke a weak cap and allowed storms to erupt during the afternoon along a slow moving frontal boundary. These storms rapidly organized into short bowing segments and then became highly linear across northwest Iowa and southwest Minnesota during the evening. Initial supercell storms produced large hail with as much as 2000-3000 J/kg MLCAPE, but DCAPE of around 750-1000 J/kg allowed for the development of organized cold pools and an increasing wind threat. Several brief and highly visible tornadic spin-ups developed along the line of storms by late afternoon and evening across far eastern South Dakota, northwest Iowa and southwest Minnesota.||In addition, repeated thunderstorms brought as much as 2-4 inches of rain in a short period of time to portions of Plymouth and southern Sioux County in northwest Iowa. This same area had also received locally heavy rainfall during the previous days, resulting in spotty flooding of already saturated locations.

Video documented a brief tornado in an open field around 5 miles west-southwest of Royal. The tornado was estimated to touch down around one-half mile east of 100th Avenue along 420th Street. The tornado tracked east-northeast for less than two minutes across open fields before lifting around one-quarter mile north of 420th Street one-half mile west of 120th Avenue. There were no damage indicators present to derive a rating. The average path width was estimated at 20 yards based on video evidence.

A very brief tornado was observed in an open field around 3 miles southeast of Royal. The tornado was estimated to touch down around one-half mile southwest of the intersection of 420th Street and 170th Avenue. The tornado tracked east-northeast across open fields for around one minute before lifting south of 420th Street. There were no damage indicators present to derive a rating. The average path width was estimated at 20 yards based on video evidence.

From NOAA NCEI's Storm Events Database, the narrative the local forecast office wrote for Storm Data.

5 minutes of warning. NWS FSD issued a tornado warning for this county at 01:26 UTC, 5 minutes before the tornado touched down, in force until 01:54 UTC.

The county was under a tornado watch, issued at 18:42 UTC and running to 03:00 UTC.

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 Storm Prediction Center had this point in a Enhanced Risk, with a 0.15 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 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.

The Sioux Falls radar (KFSD), 126 km away, was scanning. The volume nearest the touchdown began at 01:28 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.

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

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

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

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

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.

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.