Tornadoes · United States · North Dakota · 2020

EF1 tornado, Cuba, North Dakota, August 9, 2020

This EF1 tornado ran 2.9 miles across Barnes County on August 9, 2020, touching down at 2:17 PM CDT and reaching 150 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 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.

The record

Rating
EF1
Date
August 9, 2020
Touchdown
2:17 PM CDT (19:17 UTC)
Lifted
2:24 PM CDT (19:24 UTC)
On the ground
7 minutes
Path length
2.9 miles (4.6 km)
Path width
150 yards (137 m)
Deaths
0
Injuries
0
County
Barnes County
Touchdown point
46.850, -97.840
Lift-off point
46.843, -97.780
Record number
2008091317-01

What the Weather Service recorded

A cold front moved across eastern North Dakota and the northwest quarter of Minnesota on Sunday, August 9th. Abundant moisture remained in place, with dew points in the upper 60s to lower 70s. Thunderstorms formed across the area, producing large hail, damaging wind gusts, and tornadoes.

This tornado and the preceding funnel were viewed from several angles and locations. The tornado snapped or shattered trees in at least one shelterbelt. Peak winds were estimated at 95 mph.

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

The warnings

3 minutes of warning. NWS FGF issued a tornado warning for this county at 19:14 UTC, 3 minutes before the tornado touched down, in force until 19:32 UTC.

The county was under a severe thunderstorm watch, issued at 17:52 UTC and running to 21:16 UTC.

Issued (UTC)ExpiredProductOffice
17:52 UTC21:16 UTCSevere Thunderstorm WatchFGF
19:14 UTC19:32 UTCTornado 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 Slight Risk, with a 0.02 chance of a tornado within 25 miles. The outlook in force was issued at 16:16 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.

Bismarck Municip, ND (KBIS), 12:00Z

7.3 hours before the tornado, 220 km from the path. August 9, 2020.

Skew-T log-pSkew-T log-p diagram, Bismarck Municip, ND at 12:00Z on 2020-08-09Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel lifted from the surface. Mixed-layer CAPE 2140 joules per kilogram, CIN -174, lifted condensation level 843 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, Bismarck Municip, ND at 12:00Z on 2020-08-09The 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 95 square meters per square second, 0 to 6 km bulk shear 27 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
2140 J/kg
Mixed-layer CIN
-174 J/kg
Surface CAPE
0 J/kg
Mixed-layer LCL
843 m above ground
0-6 km bulk shear
27 kt
0-1 km bulk shear
18 kt
0-1 km storm-relative helicity
95 m²/s²
0-3 km storm-relative helicity
127 m²/s²
Significant tornado parameter
0.0
Supercell composite
1.5
0-3 km lapse rate
3.4 K/km

Open this sounding in Storm Lab

Bismarck Municip, ND (KBIS), 00:00Z

4.7 hours after it, 220 km from the path. August 10, 2020.

Skew-T log-pSkew-T log-p diagram, Bismarck Municip, ND at 00:00Z on 2020-08-10Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel lifted from the surface. Mixed-layer CAPE 0 joules per kilogram, CIN -88271, lifted condensation level 2738 meters above ground. Wind barbs in knots down the right edge.LCL10008507005003002001001 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, Bismarck Municip, ND at 00:00Z on 2020-08-10The 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 -79 square meters per square second, 0 to 6 km bulk shear 46 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
0 J/kg
Mixed-layer CIN
-88271 J/kg
Surface CAPE
0 J/kg
Mixed-layer LCL
2738 m above ground
0-6 km bulk shear
46 kt
0-1 km bulk shear
11 kt
0-1 km storm-relative helicity
-79 m²/s²
0-3 km storm-relative helicity
-104 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0
0-3 km lapse rate
7.1 K/km

Open this sounding in Storm Lab

The radar

The Fargo/Grand Forks radar (KMVX), 84 km away, was scanning. The volume nearest the touchdown began at 19:14 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
19:12 UTCFUNNEL CLOUD5 Sw OriskaBarnes, NDFUNNEL VIEWED FROM INTERSTATE 94.
19:12 UTCFUNNEL CLOUD5 Sw OriskaBarnes, NDFUNNEL VIEWED FROM INTERSTATE 94.
19:17 UTCTORNADO 16 Ssw OriskaBarnes, NDREPORT AND PHOTO POSTED VIA SOCIAL MEDIA. THIS TORNADO TRACKED EASTWARD FOR ABOUT 3 TO 4 MILES AND LIFTED BY 224 PM CDT, ABOUT 6 SSE OR ORISKA. THIS TORNADO AND THE PRECEEDING FUNNEL WERE VIEWED FROM SEVERAL ANGLES AND L
19:17 UTCTORNADO6 Ssw OriskaBarnes, NDREPORT AND PHOTO POSTED VIA SOCIAL MEDIA.
19:17 UTCTORNADO6 Ssw OriskaBarnes, NDREPORT AND PHOTO POSTED VIA SOCIAL MEDIA.
20:31 UTCHAIL 14 W VeronaLamoure, ND
20:34 UTCTSTM WND GST 48ProsperCass, NDPEAK WINDS MEASURED AT A PERSONAL WEATHER STATION.
20:35 UTCHAIL 1VeronaLamoure, NDLOTS OF NICKEL SIZE HAIL WITH A FEW QUARTERS MIXED IN.
20:40 UTCHAIL 0.886 E VeronaRansom, ND

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 North DakotaEvery tornado in North Dakota since 1950Warnings in force in North Dakota nowThe forecast where you are

The other tornadoes of August 9, 2020

12 more were confirmed in the United States that day.

DateTimeRatingWherePath (mi)Width (yd)DeathsInjuriesDamage
August 911:58 AM CDTEF0Cavalier, ND0.340
August 92:02 PM CDTEF1LaMoure, ND0.9100$225,000
August 92:13 PM CDTUnratedLaMoure, ND2.2100
August 92:13 PM CDTEF1Pennington, MN22.0200
August 92:19 PM CDTUnratedLaMoure, ND0.350
August 92:40 PM CDTEF0Traill, ND2.040
August 93:20 PM CDTEF1Beltrami, MN0.3100
August 96:15 PM EDTEF0Manatee, FL0.2100$20,000
August 97:44 PM CDTEF1Vilas, WI6.2400
August 98:28 PM CDTEF1Vilas, WI5.9250
August 99:12 PM CDTEF1Iron, WI to MI4.6250$70,000
August 99:56 PM CDTEF1Iron, MI3.8250$100,000

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.