EF2 tornado, Herman Muni Arpt to Hoffman, Minnesota, August 14, 2020

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 mphthis tornado

   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

EF2

Date

August 14, 2020

Touchdown

3:42 PM CDT (20:42 UTC)

Lifted

4:08 PM CDT (21:08 UTC)

On the ground

26 minutes

Path length

13.4 miles (21.6 km)

Path width

150 yards (137 m)

Deaths

0

Injuries

0

County

Grant County

Touchdown point

45.910, -96.080

Lift-off point

46.033, -95.865

Record number

2008141442-01

During the very early morning hours of Friday, August 14th, sporadic slow moving severe thunderstorms formed across portions of west central Minnesota. These resulted in reports of large hail, strong wind gusts, and flash flooding. Prior to sunrise and through Friday morning, additional storms developed back westward into southeast North Dakota, and they continued to fire across west central Minnesota. These storms continued to produce large hail, gusty winds, and flash flooding. By mid-afternoon, an area of surface low pressure tracked through west central Minnesota, dragging a cold front behind it. Five tornadoes occurred during this period across Grant County, Minnesota.

This tornado was the fourth of five tornadoes in Grant County. The tornado crossed U. S. Highway 59 about two miles south of Elbow Lake, the south end of Pomme de Terre Lake, and the Tipsinah Mounds Golf Course. It snapped and uprooted numerous trees, several power poles, and ravaged corn fields. It tore down a small tower, roofing, and roof sections from homes and a golf course clubhouse. Peak winds were estimated at 115 mph.

This tornado was the fifth and southernmost of five tornadoes that occurred in Grant County. This tornado had a persistent wall cloud for several minutes prior to tornado development. The tornado quickly became wrapped in heavy rain. It snapped or uprooted several trees, and tore roofing off of a home and a pole shed before passing over highway 55, as confirmed by video and a storm damage survey. Peak winds were estimated at 95 mph.

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

4 minutes of warning. NWS FGF issued a tornado warning for this county at 20:38 UTC, 4 minutes before the tornado touched down, in force until 21:15 UTC.

The county was under a tornado watch, issued at 19:39 UTC and running to 21:47 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 0.05 chance of a tornado within 25 miles. The outlook in force was issued at 19:59 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.

Elbow Lake (Y63), 2 km from the path, in the two hours either side.

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

The Aberdeen radar (KABR), 198 km away, was scanning. The volume nearest the touchdown began at 20:44 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 2020 tornado in MinnesotaEvery tornado in Minnesota since 1950Warnings in force in Minnesota nowThe forecast where you are

30 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.