Tornadoes · United States · North Dakota · 2011

EF1 tornado, Revere to Hannaford, North Dakota, July 16, 2011

From Revere to Hannaford, this EF1 tornado ran 1.2 miles across Griggs County on July 16, 2011, touching down at 7:10 PM CDT and reaching 50 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
July 16, 2011
Touchdown
7:10 PM CDT (00:10 UTC)
Lifted
7:14 PM CDT (00:14 UTC)
On the ground
4 minutes
Path length
1.2 miles (1.9 km)
Path width
50 yards (46 m)
Deaths
0
Injuries
0
Crop damage
$20,000
County
Griggs County
Touchdown point
47.280, -98.330
Lift-off point
47.320, -98.319
Record number
1107161810-01

What the Weather Service recorded

The 16th was hot and humid with late afternoon temperatures topping out in the 80s to around 90 and dew point temperatures well into the 70s. This created a large amount of instability. By early in the evening, thunderstorms began to flare up again aided by a weak low level jet.

This tornado was first reported by an observer located south of Sutton and looking east towards Hannaford. The tornado snapped down several trees in a shelterbelt and flattened part of a corn field before lifting. Peak winds were estimated at 95 mph.

The tornado knocked down several trees in various shelterbelts along its route. At one farmstead several sheets of steel roofing were ripped up and tossed off of a shed and numerous tree branches were scattered about. 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

0 minutes of warning. NWS FGF issued a tornado warning for this county at 00:10 UTC, 0 minutes before the tornado touched down, in force until 01:00 UTC.

The county was under a tornado watch, issued at 22:00 UTC and running to 05:00 UTC.

Issued (UTC)ExpiredProductOffice
11:49 UTC15:00 UTCDense Fog AdvisoryFGF
16:01 UTC16:22 UTCSevere Thunderstorm WarningFGF
18:00 UTC20:21 UTCExcessive Heat WarningFGF
18:00 UTC20:15 UTCExcessive Heat WatchFGF
22:00 UTC05:00 UTCTornado WatchFGF
00:10 UTC01:00 UTCTornado WarningFGF
15:00 UTC17:49 UTCSevere Thunderstorm WatchFGF
17:49 UTC20:41 UTCTornado WatchFGF

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 20:01 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

0.2 hours before the tornado, 189 km from the path. July 17, 2011.

Skew-T log-pSkew-T log-p diagram, Bismarck Municip, ND at 00:00Z on 2011-07-17Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel lifted from the surface. Mixed-layer CAPE 4274 joules per kilogram, CIN -20, lifted condensation level 1100 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 2011-07-17The 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 54 square meters per square second, 0 to 6 km bulk shear 38 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
4274 J/kg
Mixed-layer CIN
-20 J/kg
Surface CAPE
3735 J/kg
Mixed-layer LCL
1100 m above ground
0-6 km bulk shear
38 kt
0-1 km bulk shear
9 kt
0-1 km storm-relative helicity
54 m²/s²
0-3 km storm-relative helicity
205 m²/s²
Significant tornado parameter
2.4
Supercell composite
13.9
0-3 km lapse rate
6.9 K/km

Open this sounding in Storm Lab

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

11.8 hours after it, 189 km from the path. July 17, 2011.

Skew-T log-pSkew-T log-p diagram, Bismarck Municip, ND at 12:00Z on 2011-07-17Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel lifted from the surface. Mixed-layer CAPE 4227 joules per kilogram, CIN -184, lifted condensation level 1037 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 2011-07-17The 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 156 square meters per square second, 0 to 6 km bulk shear 34 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
4227 J/kg
Mixed-layer CIN
-184 J/kg
Surface CAPE
509 J/kg
Mixed-layer LCL
1037 m above ground
0-6 km bulk shear
34 kt
0-1 km bulk shear
20 kt
0-1 km storm-relative helicity
156 m²/s²
0-3 km storm-relative helicity
276 m²/s²
Significant tornado parameter
0.0
Supercell composite
37.4
0-3 km lapse rate
3.0 K/km

Open this sounding in Storm Lab

The radar

The Fargo/Grand Forks radar (KMVX), 79 km away, was scanning. The volume nearest the touchdown began at 00:12 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
00:10 UTCTORNADO15 Se SuttonGriggs, NDPERSON 5 S OF SUTTON ND SEES A TORNADO 10 MILES TO HIS EAST ... RELAYED VIA WFO BISMARCK
00:14 UTCFUNNEL CLOUD6 W CooperstownGriggs, NDPUBLIC REPORT OF FUNNEL CLOUD REPORTED ON VALLEY NEWS LIVE FACEBOOK PAGE
00:14 UTCFUNNEL CLOUD6 W HannafordGriggs, NDPUBLIC REPORT OF FUNNEL CLOUD RECEIVED VIA FACEBOOK PAGE. LOCATION ORIGINALY IDENTIFIED AS WEST OF COOPERSTOWN BUT WAS LIKELY WEST OF HANNAFORD.
00:30 UTCTORNADO6 Nw HannafordGriggs, NDTORNADO TOUCHED DOWN AND TORE THE ROOF OFF OF A SHED
01:41 UTCFUNNEL CLOUD3 S MchenryFoster, NDMULTIPLE FUNNELS.

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

This ground now

The live radar over the trackEvery 2011 tornado in North DakotaEvery tornado in North Dakota since 1950Warnings in force in North Dakota nowThe forecast where you are

The other tornadoes of July 16, 2011

9 more were confirmed in the United States that day.

DateTimeRatingWherePath (mi)Width (yd)DeathsInjuriesDamage
July 165:35 PM CDTEF1Burleigh, ND6.250$10,000
July 167:20 PM CDTEF1Griggs, ND1.0100$10,000
July 167:31 PM CDTEF0Wells, ND5.630
July 167:38 PM CDTEF0Wells, ND1.230
July 167:51 PM CDTEF0Benson, ND3.0100
July 168:18 PM CDTEF0Benson, ND3.050
July 168:25 PM CDTEF0Marshall, MN0.110
July 169:47 PM CDTEF0Emmons, ND1.930$30,000
July 169:48 PM CDTEF0Ramsey, ND0.210

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.