Tornadoes · United States · North Dakota · 2010

EF1 tornado, Crocus to Munich, North Dakota, August 1, 2010

From Crocus to Munich, this EF1 tornado ran 20.0 miles across Towner and Cavalier counties on August 1, 2010, touching down at 8:20 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 1, 2010
Touchdown
8:20 PM CDT (01:20 UTC)
Lifted
8:55 PM CDT (01:55 UTC)
On the ground
35 minutes
Path length
20.0 miles (32.2 km)
Path width
150 yards (137 m)
Deaths
0
Injuries
0
Counties
Towner and Cavalier counties
Touchdown point
48.740, -99.170
Lift-off point
48.642, -98.719
Record number
1008011920-01

What the Weather Service recorded

A persistent thunderstorm cell along the Canadian border produced a tornado and several reports of strong winds.

This tornado tracked for nearly 20 miles, about 10 miles in Towner County and 10 miles in Cavalier County. During much of this track, the tornado was likely enveloped in heavy rains and strong downburst winds with the funnel briefly visible at times. The tornado broke down two wooden power poles and numerous trees and tree limbs along its route. Peak winds were estimated at 95 mph.

This tornado began in Towner County at 820 pm CDT. The tornado tracked for about 20 miles total, about 10 miles in Towner County and then about 10 miles in Cavalier County. During much of this track the tornado was likely enveloped in heavy rains and strong downburst winds with the funnel briefly visible at times. The tornado broke down two wooden power poles and numerous trees and tree limbs along its route. 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

10 minutes of warning. NWS FGF issued a tornado warning for this county at 01:10 UTC, 10 minutes before the tornado touched down, in force until 02:15 UTC.

Issued (UTC)ExpiredProductOffice
00:37 UTC01:30 UTCSevere Thunderstorm WarningFGF
01:10 UTC02:15 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 00:52 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), 00:00Z

1.3 hours before the tornado, 251 km from the path. August 2, 2010.

Skew-T log-pSkew-T log-p diagram, Bismarck Municip, ND at 00:00Z on 2010-08-02Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel lifted from the surface. Mixed-layer CAPE 1681 joules per kilogram, CIN -23, lifted condensation level 1013 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 00:00Z on 2010-08-02The 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 15 square meters per square second, 0 to 6 km bulk shear 51 knots.1939587897Sfc1 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
1681 J/kg
Mixed-layer CIN
-23 J/kg
Surface CAPE
2355 J/kg
Mixed-layer LCL
1013 m above ground
0-6 km bulk shear
51 kt
0-1 km bulk shear
10 kt
0-1 km storm-relative helicity
15 m²/s²
0-3 km storm-relative helicity
75 m²/s²
Significant tornado parameter
0.5
Supercell composite
2.5
0-3 km lapse rate
7.0 K/km

Open this sounding in Storm Lab

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

10.7 hours after it, 251 km from the path. August 2, 2010.

Skew-T log-pSkew-T log-p diagram, Bismarck Municip, ND at 12:00Z on 2010-08-02Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel lifted from the surface. Mixed-layer CAPE 285 joules per kilogram, CIN -191, lifted condensation level 1501 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 2010-08-02The 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 -5 square meters per square second, 0 to 6 km bulk shear 24 knots.1939587897Sfc1 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
285 J/kg
Mixed-layer CIN
-191 J/kg
Surface CAPE
51 J/kg
Mixed-layer LCL
1501 m above ground
0-6 km bulk shear
24 kt
0-1 km bulk shear
15 kt
0-1 km storm-relative helicity
-5 m²/s²
0-3 km storm-relative helicity
32 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.2
0-3 km lapse rate
4.4 K/km

Open this sounding in Storm Lab

The surface observations

Devils_lake (DVL), 64 km from the path, in the two hours either side.

Time (UTC)Temp (°F)Dew point (°F)WindGust (kt)Pressure (mb)Weather
23:35 UTC80.664.4140° 9 kt1007.8
23:55 UTC78.864.4140° 7 kt1007.8
00:15 UTC78.864.4140° 9 kt1007.8
00:35 UTC7764.4150° 9 kt1007.5
00:55 UTC78.864.4150° 7 kt1007.5
01:15 UTC7764.4150° 5 kt1007.8
01:35 UTC7766.2180° 3 kt1008.1
01:55 UTC7766.2220° 4 kt1007.8
02:15 UTC75.266.2130° 8 kt1007.5
02:35 UTC73.466.2130° 5 kt1007.5
02:55 UTC73.466.230° 4 kt1007.8
03:15 UTC71.666.220° 3 kt1008.5

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

What was reported nearby

Local storm reports within 60 km of the path, in the three hours either side.

Time (UTC)ReportWhereCountyRemark
01:15 UTCTSTM WND DMGRocklakeTowner, ND10 INCH DIAMETER TREES FELLED. GARAGE PUSHED OFF FOUNDATION. LEG OF A FERTILIZER PLANT TOPPLED OVER. REPORTED BY ND ARB OBSERVER.
01:20 UTCTORNADO 15 Se RocklakeTowner, NDTORNADO TRACKED FOR NEARLY 20 MILES TO AROUND 5 ESE OF MUNICH BY 855 PM CDT. DURING MUCH OF THIS TRACK THE TORNADO WAS LIKELY ENVELOPED IN HEAVY RAINS AND STRONG DOWN BURST WINDS WITH THE FUNNEL BREIFLY VISIBLE AT TIMES.
01:20 UTCTORNADO5 Se RocklakeTowner, NDNWS STORM DAMAGE CONFIRMS WEAK EF1 TORNADO FROM ABOUT 5 MILES SOUTHEAST OF ROCKLAKE TO 5 MILES EAST OF MUNICH.
01:40 UTCTSTM WND DMGMunichCavalier, ND16 INCH TREES SNAPPED,POSSIBLE FUNNEL CLOUD BUT RAIN WRAPPING PRECLUDES DEFINITIVE DETERMINATION.
02:45 UTCTORNADO14 Sw RollaRolette, NDTORNADO OBSERVED FOR 5 MINUTES. CORRECTED LOCATION OF TORNADO TO 14 SOUTHWEST OF ROLLA.
02:45 UTCTORNADO7 Sw RollaRolette, NDTORNADO OBSERVED FOR 5 MINUTES.
02:54 UTCTORNADO5 S RollaRolette, NDBRIEF TOUCHDOWN REPORTED TO STATE RADIO AT 954 PM CDT.
02:56 UTCTORNADO1 N RoletteRolette, ND

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

This ground now

The live radar over the trackEvery 2010 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 1, 2010

2 more were confirmed in the United States that day.

DateTimeRatingWherePath (mi)Width (yd)DeathsInjuriesDamage
August 18:16 PM MDTEF0Mercer, ND1.640$50,000
August 19:45 PM CDTEF0Rolette, ND5.830

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.