Tornadoes · United States · Minnesota · 2021
Unrated tornado, Sunburg, Minnesota, August 20, 2021
This Unrated tornado ran 0.1 miles across Kandiyohi County on August 20, 2021, touching down at 6:30 PM CDT and reaching 10 yards wide. It killed nobody.
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.
EF065 to 85 mph
Light damage. Surface peeled off some roofs, gutters and siding damaged, branches broken, shallow-rooted trees pushed over.
EF186 to 110 mph
Moderate damage. Roofs badly stripped, mobile homes overturned or badly damaged, exterior doors lost, windows broken.
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.
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.
EF4166 to 200 mph
Devastating damage. Well-built houses leveled, structures with weak foundations moved some distance, cars thrown and large missiles generated.
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.
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.
The record
- Rating
- Unrated
- Date
- August 20, 2021
- Touchdown
- 6:30 PM CDT (23:30 UTC)
- Lifted
- 6:31 PM CDT (23:31 UTC)
- On the ground
- 1 minutes
- Path length
- 0.1 miles (0.1 km)
- Path width
- 10 yards (9 m)
- Deaths
- 0
- Injuries
- 0
- County
- Kandiyohi County
- Touchdown point
- 45.394, -95.093
- Lift-off point
- 45.395, -95.092
- Record number
- 2108201730-01
What the Weather Service recorded
Scattered thunderstorms developed along an increasing thermal gradient across western Minnesota during the afternoon of Friday, August 20th. These storms congealed into small bow segments that produced severe wind gusts near Alexandria, and two brief tornadoes. This area of storms continued to progress eastward during the evening and produced a few wind gusts of 30 to 40 mph with the stronger cells.
There was a brief tornado just southeast of the intersection of Kandiyohi, Pope, and Stearns Counties. It was caught on video and moved across a bean field and road. Although it did not hit any damage indicators, video suggests the tornado was weak.
From NOAA NCEI's Storm Events Database, the narrative the local forecast office wrote for Storm Data.
The warnings
No tornado warning for this county appears in the archive as in force at the moment the tornado touched down.
The county was under a severe thunderstorm watch, issued at 21:00 UTC and running to 03:00 UTC.
| Issued (UTC) | Expired | Product | Office |
|---|---|---|---|
| 21:00 UTC | 03:00 UTC | Severe Thunderstorm Watch | MPX |
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 Slight Risk, with a 0.05 chance of a tornado within 25 miles. The outlook in force was issued at 19:34 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), 12:00Z
11.5 hours before the tornado, 132 km from the path. August 20, 2021.
- Mixed-layer CAPE
- 48 J/kg
- Mixed-layer CIN
- -139 J/kg
- Surface CAPE
- 8 J/kg
- Mixed-layer LCL
- 999 m above ground
- 0-6 km bulk shear
- 20 kt
- 0-1 km bulk shear
- 17 kt
- 0-1 km storm-relative helicity
- 62 m²/s²
- 0-3 km storm-relative helicity
- 37 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.0
- 0-3 km lapse rate
- 4.0 K/km
Minneapolis, MN (KMPX), 00:00Z
0.5 hours after it, 132 km from the path. August 21, 2021.
- Mixed-layer CAPE
- 395 J/kg
- Mixed-layer CIN
- -100 J/kg
- Surface CAPE
- 717 J/kg
- Mixed-layer LCL
- 1368 m above ground
- 0-6 km bulk shear
- 24 kt
- 0-1 km bulk shear
- 29 kt
- 0-1 km storm-relative helicity
- 233 m²/s²
- 0-3 km storm-relative helicity
- 303 m²/s²
- Significant tornado parameter
- 0.2
- Supercell composite
- 2.4
- 0-3 km lapse rate
- 6.8 K/km
The surface observations
Paynesville (PEX), 27 km from the path, in the two hours either side.
| Time (UTC) | Temp (°F) | Dew point (°F) | Wind | Gust (kt) | Pressure (mb) | Weather |
|---|---|---|---|---|---|---|
| 21:55 UTC | 84.2 | 69.8 | 160° 16 kt | 23 | 1004.7 | |
| 22:15 UTC | 82.4 | 69.8 | 150° 14 kt | 22 | 1004.7 | |
| 22:35 UTC | 80.6 | 71.6 | 150° 16 kt | 26 | 1004.1 | -RA |
| 22:55 UTC | 80.6 | 71.6 | 150° 12 kt | 21 | 1004.1 | |
| 23:15 UTC | 80.6 | 71.6 | 140° 17 kt | 24 | 1003.7 | VCTS |
| 23:35 UTC | 80.6 | 71.6 | 150° 12 kt | 20 | 1003.7 | |
| 23:55 UTC | 80.6 | 71.6 | 170° 9 kt | 20 | 1004.4 | |
| 00:15 UTC | 80.6 | 71.6 | 180° 15 kt | 21 | 1004.7 | |
| 00:35 UTC | 78.8 | 69.8 | 190° 12 kt | 18 | 1004.1 | |
| 00:55 UTC | 78.8 | 69.8 | 190° 8 kt | 15 | 1004.4 | |
| 01:15 UTC | 77 | 69.8 | 190° 10 kt | 17 | 1004.7 | |
| 01:35 UTC | 75.2 | 69.8 | 200° 10 kt | 18 | 1004.1 | -RA |
From the Iowa Environmental Mesonet's archive of airport observations.
The radar
The Minneapolis radar (KMPX), 134 km away, was scanning. The volume nearest the touchdown began at 23:27 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) | Report | Where | County | Remark |
|---|---|---|---|---|
| 21:46 UTC | TSTM WND GST 62 | 3 N Forada | Douglas, MN | MESONET STATION MN015 ALEXANDRIA 2SSE. |
| 21:51 UTC | TSTM WND GST 60 | 2 Sw Alexandria | Douglas, MN | ASOS STATION KAXN ALEXANDRIA MN ASOS. |
| 23:30 UTC | TORNADO | 4 Wsw Belgrade | Stearns, MN | BRIEF TORNADO TOUCHDOWN ABOUT 2 MILES SOUTH OF, AND BETWEEN, BELGRADE AND BROOTEN. |
| 23:51 UTC | TORNADO | 2 Nne Belgrade | Stearns, MN | BRIEF TOUCHDOWN. |
From the Iowa Environmental Mesonet's archive of National Weather Service local storm reports.
This ground now
The live radar over the trackEvery 2021 tornado in MinnesotaEvery tornado in Minnesota since 1950Warnings in force in Minnesota nowThe forecast where you are
The other tornadoes of August 20, 2021
6 more were confirmed in the United States that day.
| Date | Time | Rating | Where | Path (mi) | Width (yd) | Deaths | Injuries | Damage |
|---|---|---|---|---|---|---|---|---|
| August 20 | 3:34 PM CDT | EF0 | Osceola, IA | 3.6 | 30 | $30,000 | ||
| August 20 | 4:18 PM CDT | EF0 | Cass, ND | 0.4 | 40 | |||
| August 20 | 6:42 PM CDT | EF0 | Stearns, MN | 2.1 | 50 | |||
| August 20 | 8:03 PM CDT | Unrated | Pocahontas, IA | 1.2 | 20 | |||
| August 20 | 8:19 PM CDT | Unrated | Humboldt, IA | 2.2 | 60 | |||
| August 20 | 9:05 PM CDT | EF0 | Wright, IA | 4.0 | 190 |
What this means
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.
Sources
NOAA Storm Prediction Center tornado database, 1950-2025, the official record kept by NOAA's Storm Prediction Center.