Tornadoes · United States · Nebraska · 2017
EF0 tornado, Otoe, Nebraska, April 15, 2017
This EF0 tornado ran 1.5 miles across Otoe County on April 15, 2017, touching down at 4:58 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.
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
- April 15, 2017
- Touchdown
- 4:58 PM CDT (21:58 UTC)
- Lifted
- 5:11 PM CDT (22:11 UTC)
- On the ground
- 13 minutes
- Path length
- 1.5 miles (2.4 km)
- Path width
- 50 yards (46 m)
- Deaths
- 0
- Injuries
- 0
- County
- Otoe County
- Touchdown point
- 40.709, -96.127
- Lift-off point
- 40.701, -96.101
- Record number
- 1704151558-01
What the Weather Service recorded
An upper level storm system moved into Nebraska and Iowa on the afternoon of April 15th. This allowed for a dry line to move through southeast Nebraska with a trailing cold front moving into northeast Nebraska. Both of these boundaries served as a focus for severe weather activity. Supercells initially developed along the dry line in southeast Nebraska and moved into southwest Iowa. These thunderstorms generally produced large hail, though one tornado did occur with the initial development. Supercells then developed along the cold front in northeast Nebraska and tracked southeast, and eventually into western Iowa by late evening. These produced significant hail and wind as they tracked across the area. The severe weather threat ended by late evening as storms moved out of the area.
A tornado was observed from development to dissipation via live stream from storm chasers in the area. The tornado moved very slowly over open county and caused no damage. The tornado was highly visible due to the relatively high cloud bases associated with the supercell and was reported from several miles away from numerous sources.
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.
| Issued (UTC) | Expired | Product | Office |
|---|---|---|---|
| 21:45 UTC | 22:15 UTC | Severe Thunderstorm Warning | OAX |
| 21:59 UTC | 22:30 UTC | Tornado Warning | OAX |
| 22:06 UTC | 02:33 UTC | Severe Thunderstorm Watch | OAX |
| 22:21 UTC | 22:45 UTC | Severe Thunderstorm Warning | OAX |
| 22:43 UTC | 23:15 UTC | Severe Thunderstorm Warning | OAX |
| 23:16 UTC | 23:45 UTC | Severe Thunderstorm Warning | OAX |
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. The outlook in force was issued at 19:53 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.
Omaha, NE (KOAX), 12:00Z
10.0 hours before the tornado, 72 km from the path. April 15, 2017.
- Mixed-layer CAPE
- 0 J/kg
- Mixed-layer CIN
- -90336 J/kg
- Surface CAPE
- 0 J/kg
- Mixed-layer LCL
- 1748 m above ground
- 0-6 km bulk shear
- 40 kt
- 0-1 km bulk shear
- 4 kt
- 0-1 km storm-relative helicity
- -29 m²/s²
- 0-3 km storm-relative helicity
- -118 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- -0.0
- 0-3 km lapse rate
- 3.3 K/km
Omaha, NE (KOAX), 00:00Z
2.0 hours after it, 72 km from the path. April 16, 2017.
- Mixed-layer CAPE
- 1034 J/kg
- Mixed-layer CIN
- -55 J/kg
- Surface CAPE
- 2175 J/kg
- Mixed-layer LCL
- 1322 m above ground
- 0-6 km bulk shear
- 49 kt
- 0-1 km bulk shear
- 10 kt
- 0-1 km storm-relative helicity
- -9 m²/s²
- 0-3 km storm-relative helicity
- 76 m²/s²
- Significant tornado parameter
- 0.1
- Supercell composite
- 0.8
- 0-3 km lapse rate
- 7.2 K/km
The surface observations
Nebraska City (AFK), 24 km from the path, in the two hours either side.
| Time (UTC) | Temp (°F) | Dew point (°F) | Wind | Gust (kt) | Pressure (mb) | Weather |
|---|---|---|---|---|---|---|
| 20:15 UTC | 76 | 58.8 | 200° 20 kt | 25 | 1008.1 | |
| 20:35 UTC | 77.2 | 56.8 | 200° 19 kt | 29 | 1008.1 | |
| 20:55 UTC | 76.5 | 57.7 | 210° 15 kt | 19 | 1008.1 | |
| 21:15 UTC | 76.5 | 57.7 | 190° 17 kt | 22 | 1007.8 | |
| 21:35 UTC | 77.4 | 58 | 200° 17 kt | 26 | 1007.1 | |
| 21:55 UTC | 75.6 | 57.7 | 190° 18 kt | 25 | 1006.8 | |
| 22:15 UTC | 75.6 | 58 | 190° 16 kt | 21 | 1006.4 | |
| 22:35 UTC | 75.7 | 59 | 190° 20 kt | 27 | 1006.1 | -VCTSRA |
| 22:55 UTC | 75 | 60.3 | 210° 16 kt | 24 | 1005.8 | -RA |
| 23:15 UTC | 72.5 | 60.8 | 350° 11 kt | 18 | 1006.4 | TSRA |
| 23:35 UTC | 69 | 60.3 | 300° 10 kt | 1007.5 | -TSRA | |
| 23:55 UTC | 72.3 | 62.2 | 360° 9 kt | 18 | 1007.8 | -VCTSRA |
From the Iowa Environmental Mesonet's archive of airport observations.
The radar
The Omaha radar (KOAX), 72 km away, was scanning. The volume nearest the touchdown began at 21:59 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 |
|---|---|---|---|---|
| 21:44 UTC | HAIL 1.75 | Murray | Cass, NE | |
| 21:44 UTC | HAIL 1.75 | Murray | Cass, NE | |
| 21:50 UTC | HAIL 1.5 | 2 S Plattsmouth | Cass, NE | |
| 21:56 UTC | HAIL 1 | Plattsmouth | Cass, NE | |
| 21:58 UTC | TORNADO | 1 Nne Dunbar | Otoe, NE |
From the Iowa Environmental Mesonet's archive of National Weather Service local storm reports.
This ground now
The live radar over the trackEvery 2017 tornado in NebraskaEvery tornado in Nebraska since 1950Warnings in force in Nebraska nowThe forecast where you are
The other tornadoes of April 15, 2017
5 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.