Unrated tornado, Williston, North Dakota, June 10, 2021

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

Unrated

Date

June 10, 2021

Touchdown

9:57 PM CDT (02:57 UTC)

Lifted

10:00 PM CDT (03:00 UTC)

On the ground

3 minutes

Path length

0.9 miles (1.5 km)

Path width

40 yards (37 m)

Deaths

0

Injuries

0

County

Williams County

Touchdown point

48.160, -103.540

Lift-off point

48.168, -103.524

Record number

2106102057-01

A strong short-wave trough moved into the Northern Plains as a slow moving warm front lifted through North Dakota. Very strong instability developed by afternoon, along with increased deep layer shear. The initial storms occurred over west-central and northwest North Dakota. The main concern with these storms was large hail and tornadoes. Multiple tornadoes occurred over western McKenzie County over a similar location, and one occurred in Williams County. Photos of the tornadoes submitted to the National Weather Service indicate that one of them in McKenzie County was quite large. With that said, no damage was reported given the tornadoes occurred in rugged terrain over a rural area, so all were rated EF-U, EF Unknown. As the evening went on, the threats shifted to a mix of strong winds, hail, and heavy rain. The city of Williston was hit the hardest with multiple storms passing over in a short period of time. Flash flooding occurred in the city, which floated vehicles and flooded basements. Hail to the size of tennis balls also fell, causing extensive home and vehicle damage. In addition, very strong winds were reported at the Williston airport, with gusts to 82 mph with one storm, then gusts to 93 mph with the next, causing roof damage. Later in the night the storms became more linear and grew towards the south, while the overall lines moved east. Wind became the primary concern as the storms moved towards the James River Valley where multiple wind damage events occurred. For the whole event, the largest hail reported was the size of tennis balls, in Williston in Williams County. The strongest reported wind gust was 93 mph at the Williston Airport, also in Williams County.

The tornado touched down in an open field east of Williston. There was no damage to evaluate and so by National Weather Service policy the tornado is rated EF Unknown.

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

8 minutes of warning. NWS BIS issued a tornado warning for this county at 02:49 UTC, 8 minutes before the tornado touched down, in force until 03:15 UTC.

The county was under a severe thunderstorm watch, issued at 02:54 UTC and running to 07:09 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 Moderate Risk, with a 0.10 chance of a tornado within 25 miles. The outlook in force was issued at 01:10 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 Minot AFB radar (KMBX), 199 km away, was scanning. The volume nearest the touchdown began at 02:57 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 2021 tornado in North DakotaEvery tornado in North Dakota since 1950Warnings in force in North Dakota nowThe forecast where you are

3 more were confirmed in the United States that day.

Ratings are the survey's, read off the damage rather than measured; the rating scale is above. Tornado counts rise through the record as reporting improved, so a year in the 1950s is not comparable with one today except for the strongest tornadoes, which were always noticed.

NOAA Storm Prediction Center tornado database, 1950-2025, the official record kept by NOAA's Storm Prediction Center.