Tornadoes · United States · Minnesota · 2011

EF0 tornado, Stephen Arpt, Minnesota, July 16, 2011

This EF0 tornado ran 0.1 miles across Marshall County on July 16, 2011, touching down at 8:25 PM CDT and reaching 10 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 16, 2011
Touchdown
8:25 PM CDT (01:25 UTC)
Lifted
8:26 PM CDT (01:26 UTC)
On the ground
1 minutes
Path length
0.1 miles (0.2 km)
Path width
10 yards (9 m)
Deaths
0
Injuries
0
County
Marshall County
Touchdown point
48.520, -96.840
Lift-off point
48.520, -96.840
Record number
1107161925-01

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.

A brief touchdown with dust swirl was noted in a open field. Peak winds were estimated at 70 mph.

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

The warnings

31 minutes of warning. NWS FGF issued a tornado warning for this county at 00:54 UTC, 31 minutes before the tornado touched down, in force until 01:45 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
18:00 UTC09:11 UTCExcessive Heat WatchFGF
18:00 UTC20:21 UTCHeat AdvisoryFGF
22:00 UTC05:00 UTCTornado WatchFGF
00:54 UTC01:45 UTCTornado WarningFGF
01:42 UTC02:30 UTCTornado WarningFGF
02:44 UTC03:45 UTCSevere Thunderstorm WarningFGF
03:38 UTC04:15 UTCSevere Thunderstorm WarningFGF
03:42 UTC12:00 UTCFlood AdvisoryFGF
04:08 UTC05:00 UTCSevere Thunderstorm WarningFGF
05:56 UTC06:22 UTCSevere Thunderstorm WarningFGF
15:00 UTC20:38 UTCSevere Thunderstorm 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 00:38 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.

International Fa, MN (KINL), 00:00Z

1.4 hours before the tornado, 261 km from the path. July 17, 2011.

Skew-T log-pSkew-T log-p diagram, International Fa, MN 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 1181 joules per kilogram, CIN -107, lifted condensation level 1398 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, International Fa, MN 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 121 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
1181 J/kg
Mixed-layer CIN
-107 J/kg
Surface CAPE
2864 J/kg
Mixed-layer LCL
1398 m above ground
0-6 km bulk shear
38 kt
0-1 km bulk shear
17 kt
0-1 km storm-relative helicity
121 m²/s²
0-3 km storm-relative helicity
115 m²/s²
Significant tornado parameter
0.2
Supercell composite
4.9
0-3 km lapse rate
6.4 K/km

Open this sounding in Storm Lab

International Fa, MN (KINL), 12:00Z

10.6 hours after it, 261 km from the path. July 17, 2011.

Skew-T log-pSkew-T log-p diagram, International Fa, MN 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 1146 joules per kilogram, CIN -217, lifted condensation level 1112 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, International Fa, MN 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 167 square meters per square second, 0 to 6 km bulk shear 47 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
1146 J/kg
Mixed-layer CIN
-217 J/kg
Surface CAPE
592 J/kg
Mixed-layer LCL
1112 m above ground
0-6 km bulk shear
47 kt
0-1 km bulk shear
30 kt
0-1 km storm-relative helicity
167 m²/s²
0-3 km storm-relative helicity
135 m²/s²
Significant tornado parameter
0.0
Supercell composite
1.0
0-3 km lapse rate
3.9 K/km

Open this sounding in Storm Lab

The surface observations

Hallock (HCO), 27 km from the path, in the two hours either side.

Time (UTC)Temp (°F)Dew point (°F)WindGust (kt)Pressure (mb)Weather
23:33 UTC89.678.8220° 7 kt1009.8
23:54 UTC89.678.8210° 4 kt1009.8
00:14 UTC87.878.8170° 5 kt1009.8
00:34 UTC8678.8150° 4 kt1009.5
00:53 UTC84.278.8150° 3 kt1009.5
01:14 UTC8680.6130° 5 kt1009.1TS
01:34 UTC84.278.8120° 4 kt1009.1-TSRA
01:53 UTC82.473.4170° 7 kt1009.5TS
02:14 UTC78.871.6130° 6 kt1009.5VCTS
02:34 UTC78.871.6120° 6 kt101009.1VCTS
02:53 UTC7771.6100° 9 kt1009.1TS
03:14 UTC75.271.6140° 5 kt1009.5VCTS

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

The radar

The Fargo/Grand Forks radar (KMVX), 116 km away, was scanning. The volume nearest the touchdown began at 01:25 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
02:06 UTCHAIL 0.75KarlstadKittson, MN
02:10 UTCHAIL 1KarlstadKittson, MNMOSTLY PEA SIZED HAIL BUT A FEW QUARTERS IN THE MIX
03:15 UTCHEAVY RAIN 3.95KarlstadKittson, MNSTREET FLOODING CONTINUES TO WORSEN IN KARLSTAD.
03:28 UTCHAIL 11 E StrathconaRoseau, MNDECK COVERED WITH QUARTER SIZED HAIL...SOME BIGGER BUT NOT AS LARGE AS HALF DOLLARS
03:57 UTCTSTM WND GST 61HallockKittson, MN

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 MinnesotaEvery tornado in Minnesota since 1950Warnings in force in Minnesota 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 167:10 PM CDTEF1Griggs, ND1.250
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 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.