Tornadoes · United States · Minnesota · 2020

EF0 tornado, Rollag, Minnesota, July 25, 2020

This EF0 tornado ran 0.4 miles across Clay County on July 25, 2020, touching down at 2:26 AM CDT and reaching 40 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.

  1. EF065 to 85 mphthis tornado

    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. 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.

The record

Rating
EF0
Date
July 25, 2020
Touchdown
2:26 AM CDT (07:26 UTC)
Lifted
2:27 AM CDT (07:27 UTC)
On the ground
1 minutes
Path length
0.4 miles (0.6 km)
Path width
40 yards (37 m)
Deaths
0
Injuries
0
Crop damage
$5,000
County
Clay County
Touchdown point
46.770, -96.250
Lift-off point
46.770, -96.250
Record number
2007250126-01

What the Weather Service recorded

Friday, July 24th, was one of the hottest and most humid days of 2020. Afternoon high temperatures ranged from the upper 80s to middle 90s, with dew points in the middle 70s to lower 80s. During the early evening, thunderstorms broke out along two lines, one from Bismarck to northwest of Grand Forks, and the other from Bismarck to west of Fargo. By the late evening, the strongest storms along both lines were converging toward Grand Forks. This brought a period of very strong winds to eastern Grand Forks and eastern Walsh counties, continuing up toward the Lake of the Woods region. Meanwhile, another cluster of storms over south central North Dakota moved east-northeast, tracking through the Fargo-Moorhead area and into west central Minnesota during the overnight hours. These storms also produced some strong wind gusts.

A weak tornado formed in the bookend vortex portion of a squall line. The tornado knocked down sunflowers and left a distinctive swirl pattern. Peak winds were estimated at 65 mph.

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.

Issued (UTC)ExpiredProductOffice
17:00 UTC08:26 UTCExcessive Heat WatchFGF
17:00 UTC01:00 UTCExcessive Heat WarningFGF
04:41 UTC05:45 UTCSevere Thunderstorm WarningFGF
05:42 UTC06:09 UTCSevere Thunderstorm WarningFGF
07:05 UTC11:38 UTCFlood AdvisoryFGF
07:23 UTC07:52 UTCSevere Thunderstorm WarningFGF

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 Marginal Risk. The outlook in force was issued at 06:03 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.

Aberdeen, SD (KABR), 00:00Z

7.4 hours before the tornado, 266 km from the path. July 25, 2020.

Skew-T log-pSkew-T log-p diagram, Aberdeen, SD at 00:00Z on 2020-07-25Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel lifted from the surface. Mixed-layer CAPE 2265 joules per kilogram, CIN -36, lifted condensation level 1499 meters above ground. Wind barbs in knots down the right edge.LCLLFCEL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°0°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed. The warm shading is its CAPE, the cool shading the inhibition it has to break through.
HodographHodograph, Aberdeen, SD at 00:00Z on 2020-07-25The wind through the lowest 10 kilometers as a curve, rings every 10 meters per second labeled in knots. Zero to 1 km storm-relative helicity -19 square meters per square second, 0 to 6 km bulk shear 15 knots.193958Sfc1 km3 km6 km9 kmRMLM
The wind turning with height, colored by layer: ground to 1 km, 1 to 3 km, 3 to 6 km, 6 to 10 km. RM and LM are the right and left moving storms Bunkers' method gives; the shaded area is the 0 to 1 km storm-relative helicity.
Mixed-layer CAPE
2265 J/kg
Mixed-layer CIN
-36 J/kg
Surface CAPE
3183 J/kg
Mixed-layer LCL
1499 m above ground
0-6 km bulk shear
15 kt
0-1 km bulk shear
12 kt
0-1 km storm-relative helicity
-19 m²/s²
0-3 km storm-relative helicity
48 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.6
0-3 km lapse rate
7.4 K/km

Open this sounding in Storm Lab

Aberdeen, SD (KABR), 12:00Z

4.6 hours after it, 266 km from the path. July 25, 2020.

Skew-T log-pSkew-T log-p diagram, Aberdeen, SD at 12:00Z on 2020-07-25Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel lifted from the surface. Mixed-layer CAPE 114 joules per kilogram, CIN -149, lifted condensation level 975 meters above ground. Wind barbs in knots down the right edge.LCLLFCEL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°0°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed. The warm shading is its CAPE, the cool shading the inhibition it has to break through.
HodographHodograph, Aberdeen, SD at 12:00Z on 2020-07-25The wind through the lowest 10 kilometers as a curve, rings every 10 meters per second labeled in knots. Zero to 1 km storm-relative helicity 198 square meters per square second, 0 to 6 km bulk shear 28 knots.19395878Sfc1 km3 km6 km9 kmRMLM
The wind turning with height, colored by layer: ground to 1 km, 1 to 3 km, 3 to 6 km, 6 to 10 km. RM and LM are the right and left moving storms Bunkers' method gives; the shaded area is the 0 to 1 km storm-relative helicity.
Mixed-layer CAPE
114 J/kg
Mixed-layer CIN
-149 J/kg
Surface CAPE
514 J/kg
Mixed-layer LCL
975 m above ground
0-6 km bulk shear
28 kt
0-1 km bulk shear
22 kt
0-1 km storm-relative helicity
198 m²/s²
0-3 km storm-relative helicity
163 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.2
0-3 km lapse rate
4.7 K/km

Open this sounding in Storm Lab

The radar

The Fargo/Grand Forks radar (KMVX), 117 km away, was scanning. The volume nearest the touchdown began at 07:26 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)ReportWhereCountyRemark
05:40 UTCTSTM WND DMGBorupNorman, MNA FEW LARGE 3 TO 5 INCH DIAMETER BRANCHES BROKEN DOWN.
07:15 UTCTSTM WND GST 633 Se BarnesvilleWilkin, MNPERSONAL WEATHER STATION MEASURED WIND GUST TO 62.6 MPH
07:26 UTCTSTM WND DMG1 N RollagClay, MNSUNFLOWER FIELDS FLATTENED. REPORT RECEIVED VIA SOCIAL MEDIA. TIME ESTIMATED VIA RADAR.
07:26 UTCTORNADO 02 Nnw RollagClay, MNA WEAK TORNADO FORMED IN THE BOOKEND VORTEX PORTION OF A SQUALL LINE AND TRACKED FOR LESS THAN A HALF MILE TO THE ENE, ENDING BY 227 PM CDT. THE TORNADO KNOCKED DOWN SUNFLOWERS AND LEFT A DISTINCTIVE SWIRL PATTERN. MAXIM
07:31 UTCTSTM WND DMG9 S Lake ParkBecker, MNAPPLE TREE DOWNED ON SOUTH IDE OF BIG CORMORANT LAKE. ALSO 1.58 INCHES OF RAIN. REPORT AND PHOTO POSTED VIA SOCIAL MEDIA. TIME ESTIMATED BASED ON RADAR.
07:31 UTCTSTM WND DMG9 S Lake ParkBecker, MNAPPLE TREE DOWNED ON SOUTH SIDE OF BIG CORMORANT LAKE. 1.58 INCHES OF RAIN RECEIVED. REPORT RECEIVED VIA SOCIAL MEDIA. TIME ESTIMATED VIA RADAR.
07:38 UTCTSTM WND GST 954 Sse ErhardOtter Tail, MNA MICROBURST /DOWNBURST WIND/ LIKELY INITIATED OVER THE WEST END OF LONG LAKE AND MOVED RAPIDLY EASTWARD ACROSS LONG LAKE POINT ROAD. A TRAILER HOME WAS BLOWN OVER AND DEMOLISHED. SEVERAL LARGE TREE LIMBS WERE BROKEN DOW
07:42 UTCTSTM WND DMG5 N AudubonBecker, MNNUMEROUS LARGE 3 TO 5 INCH DIAMETER TREE BRANCHES BROKEN DOWN. PHOTO AND REPORT POSTED VIA SOCIAL MEDIA. TIME ESTIMATED BASED ON RADAR.
07:42 UTCTSTM WND DMG5 N AudubonBecker, MNTHREE TO FIVE INCH DIAMETER BRANCHES DOWN BASED ON PICTURES WITH TIME ESTIMATED BASED ON RADAR.
08:05 UTCTSTM WND DMG5 S DentOtter Tail, MNINITIAL REPORTS FROM DEAD LAKE INDICATE NUMEROUS TREES UPROOTED AND DAMAGE TO DOCK LIFT. RELAYED FROM BROADCAST MEDIA VIA SOCIAL MEDIA
08:05 UTCTSTM WND DMG5 Sse DentOtter Tail, MNINITIAL REPORTS FROM DEAD LAKE INDICATE NUMEROUS TREES UPROOTED AND DAMAGE TO DOCK LIFT. RELAYED FROM BROADCAST MEDIA VIA SOCIAL MEDIA
08:05 UTCTSTM WND DMG5 Ssw DentOtter Tail, MNINITIAL REPORTS FROM DEAD LAKE INDICATE NUMEROUS TREES UPROOTED AND DAMAGE TO DOCK LIFT. RELAYED FROM BROADCAST MEDIA VIA SOCIAL MEDIA

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

This ground now

The live radar over the trackEvery 2020 tornado in MinnesotaEvery tornado in Minnesota since 1950Warnings in force in Minnesota nowThe forecast where you are

The other tornadoes of July 25, 2020

5 more were confirmed in the United States that day.

DateTimeRatingWherePath (mi)Width (yd)DeathsInjuriesDamage
July 2512:48 PM CDTUnratedRefugio, TX0.125
July 256:31 PM CDTEF1Sibley, MN1.950
July 256:37 PM CDTEF0Sibley, MN0.215
July 2510:11 PM CDTEF0Live Oak, TX2.5100$10,000
July 2510:30 PM CDTEF0Live Oak, TX0.6100$5,000

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.