EF1 tornado, Delaware County, Iowa, August 11, 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 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.

Rating, as surveyed

EF1, preliminary

Date

August 11, 2026

Touchdown

7:31 AM CDT (12:31 UTC)

Lifted

7:33 AM CDT (12:33 UTC)

On the ground

2 minutes

Path length

2.4 miles (3.9 km)

Path width

150 yards (137 m)

Deaths

0

Injuries

0

County

Delaware County

Touchdown point

42.589, -91.433

Lift-off point

42.586, -91.387

Highest wind the damage implies

110 mph

Surveyed by

NWS DVN

The office's name for it

West of Greeley Tornado

Survey last edited

August 11, 2026

Record number

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

A high-end EF1 with peak gusts of 110 MPH caused significant damage to two farmsteads at the beginning of its 2.4 mile long path. Here two farm outbuildings were destroyed along with numerous snapped trees. A power pole was also snapped at this location. The tornado was roughly 150 yards wide at this location. As the tornado moved east, it began to become smaller causing mostly tree damage.

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

16 minutes of warning. NWS DVN issued a tornado warning for this county at 12:15 UTC, 16 minutes before the tornado touched down, in force until 13:00 UTC.

The county was under a severe thunderstorm watch, issued at 12:23 UTC and running to 14:29 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 Slight Risk, with a 0.02 chance of a tornado within 25 miles. The outlook in force was issued at 05:00 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.

Monticello Municipal (MXO), 46 km from the path, in the two hours either side.

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

The Quad Cities radar (KDVN), 128 km away, was scanning. The volume nearest the touchdown began at 12:30 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

28 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.