Tornadoes · United States · Minnesota · 2011
EF0 tornado, Collis, Minnesota, July 30, 2011
This EF0 tornado ran 0.5 miles across Traverse County on July 30, 2011, touching down at 7:11 PM CDT and reaching 25 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.
EF065 to 85 mphthis tornado
Light damage. Surface peeled off some roofs, gutters and siding damaged, branches broken, shallow-rooted trees pushed over.
EF186 to 110 mph
Moderate damage. Roofs badly stripped, mobile homes overturned or badly damaged, exterior doors lost, windows broken.
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.
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.
EF4166 to 200 mph
Devastating damage. Well-built houses leveled, structures with weak foundations moved some distance, cars thrown and large missiles generated.
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.
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 30, 2011
- Touchdown
- 7:11 PM CDT (00:11 UTC)
- Lifted
- 7:18 PM CDT (00:18 UTC)
- On the ground
- 7 minutes
- Path length
- 0.5 miles (0.8 km)
- Path width
- 25 yards (23 m)
- Deaths
- 0
- Injuries
- 0
- County
- Traverse County
- Touchdown point
- 45.590, -96.290
- Lift-off point
- 45.586, -96.282
- Record number
- 1107301811-01
What the Weather Service recorded
A thunderstorm developed along a cold front sweeping southward across west central Minnesota. A weak tornado dropped from the thunderstorm in far southeast Traverse County.
The tornado touched down in a corn field near Collis and traveled slowly southeast through a tree grove. The tornado damaged the corn along with many trees with several trees uprooted.
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. One was issued for the county at another hour that day.
The county was under a severe thunderstorm watch, issued at 22:31 UTC and running to 00:54 UTC.
| Issued (UTC) | Expired | Product | Office |
|---|---|---|---|
| 16:06 UTC | 16:45 UTC | Severe Thunderstorm Warning | ABR |
| 22:31 UTC | 00:54 UTC | Severe Thunderstorm Watch | ABR |
| 00:14 UTC | 00:45 UTC | Tornado Warning | ABR |
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 20:00 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
0.2 hours before the tornado, 182 km from the path. July 31, 2011.
- Mixed-layer CAPE
- 4943 J/kg
- Mixed-layer CIN
- -34 J/kg
- Surface CAPE
- 5986 J/kg
- Mixed-layer LCL
- 961 m above ground
- 0-6 km bulk shear
- 33 kt
- 0-1 km bulk shear
- 17 kt
- 0-1 km storm-relative helicity
- 102 m²/s²
- 0-3 km storm-relative helicity
- 163 m²/s²
- Significant tornado parameter
- 2.7
- Supercell composite
- 12.6
- 0-3 km lapse rate
- 7.4 K/km
Aberdeen, SD (KABR), 12:00Z
11.8 hours after it, 182 km from the path. July 31, 2011.
- Mixed-layer CAPE
- 2478 J/kg
- Mixed-layer CIN
- -125 J/kg
- Surface CAPE
- 858 J/kg
- Mixed-layer LCL
- 710 m above ground
- 0-6 km bulk shear
- 35 kt
- 0-1 km bulk shear
- 6 kt
- 0-1 km storm-relative helicity
- 69 m²/s²
- 0-3 km storm-relative helicity
- 205 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 8.0
- 0-3 km lapse rate
- 3.7 K/km
The radar
The Aberdeen radar (KABR), 166 km away, was scanning. The volume nearest the touchdown began at 00:13 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) | Report | Where | County | Remark |
|---|---|---|---|---|
| 00:12 UTC | TORNADO | 1 N Johnson | Traverse, MN | |
| 00:18 UTC | TORNADO | 1 N Johnson | Traverse, MN | TORNADO ON GROUND FROM APPROXIMATELY 712 PM TO 718 PM CDT. DEBRIS CLOUD OBSERVED BUT NO DAMAGE REPORTED. |
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 30, 2011
2 more were confirmed in the United States that day.
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.