Tornadoes · United States · Nebraska · 2012

EF0 tornado, Santee, Nebraska, April 15, 2012

This EF0 tornado ran 0.5 miles across Knox County on April 15, 2012, touching down at 2:35 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.

  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
April 15, 2012
Touchdown
2:35 PM CDT (19:35 UTC)
Lifted
2:36 PM CDT (19:36 UTC)
On the ground
1 minutes
Path length
0.5 miles (0.7 km)
Path width
25 yards (23 m)
Deaths
0
Injuries
0
County
Knox County
Touchdown point
42.839, -97.860
Lift-off point
42.843, -97.853
Record number
1204151335-01

What the Weather Service recorded

Deep low pressure that brought several tornadoes to southeast Nebraska on April 14th, tracked across northeast Nebraska during the morning and early afternoon of April 15th. Although a front had swept through the region, there was still enough instability around to allow for the development of low-topped mini super-cell thunderstorms that spawned a couple of brief weak tornadoes under the upper low.

A brief rope tornado touchdown was observed just north of Santee.

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

The warnings

24 minutes of warning. NWS OAX issued a tornado warning for this county at 19:11 UTC, 24 minutes before the tornado touched down, in force until 20:00 UTC.

Issued (UTC)ExpiredProductOffice
03:14 UTC06:51 UTCSevere Thunderstorm WatchOAX
19:06 UTC20:00 UTCSevere Thunderstorm WarningOAX
19:11 UTC20:00 UTCTornado WarningOAX
19:30 UTC20:09 UTCTornado WarningOAX
21:00 UTC09:00 UTCWind AdvisoryOAX

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 General Thunderstorms Risk. The outlook in force was issued at 16:28 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

7.6 hours before the tornado, 209 km from the path. April 15, 2012.

Skew-T log-pSkew-T log-p diagram, Omaha, NE at 12:00Z on 2012-04-15Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel lifted from the surface. Mixed-layer CAPE 308 joules per kilogram, CIN -118, lifted condensation level 599 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, Omaha, NE at 12:00Z on 2012-04-15The 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 262 square meters per square second, 0 to 6 km bulk shear 92 knots.1939587897117Sfc1 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
308 J/kg
Mixed-layer CIN
-118 J/kg
Surface CAPE
12 J/kg
Mixed-layer LCL
599 m above ground
0-6 km bulk shear
92 kt
0-1 km bulk shear
36 kt
0-1 km storm-relative helicity
262 m²/s²
0-3 km storm-relative helicity
342 m²/s²
Significant tornado parameter
0.0
Supercell composite
1.7
0-3 km lapse rate
3.8 K/km

Open this sounding in Storm Lab

Omaha, NE (KOAX), 00:00Z

4.4 hours after it, 209 km from the path. April 16, 2012.

Skew-T log-pSkew-T log-p diagram, Omaha, NE at 00:00Z on 2012-04-16Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel lifted from the surface. Mixed-layer CAPE 65 joules per kilogram, CIN -4, lifted condensation level 991 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, Omaha, NE at 00:00Z on 2012-04-16The 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 104 square meters per square second, 0 to 6 km bulk shear 78 knots.1939587897117136156Sfc1 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
65 J/kg
Mixed-layer CIN
-4 J/kg
Surface CAPE
253 J/kg
Mixed-layer LCL
991 m above ground
0-6 km bulk shear
78 kt
0-1 km bulk shear
23 kt
0-1 km storm-relative helicity
104 m²/s²
0-3 km storm-relative helicity
92 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.1
0-3 km lapse rate
7.3 K/km

Open this sounding in Storm Lab

The radar

The Sioux Falls radar (KFSD), 123 km away, was scanning. The volume nearest the touchdown began at 19:36 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
19:23 UTCHAIL 0.75VerdigreKnox, NEHAIL MOSTLY PEA SIZE BUT A FEW UP TO PENNY SIZE. REPORTED BY COOPERATIVE OBSERVER FROM ANOTHER TOWN THAT WAS IN VERDIGRE AT THE TIME.
19:27 UTCTORNADO1 S VerdigreKnox, NEBRIEF TOUCH DOWN. NO DAMAGE.
19:35 UTCTORNADO1 N SanteeKnox, NEROPE TORNADO. BRIEF TOUCHDOWN.
19:38 UTCFUNNEL CLOUD3 Se NiobraraKnox, NE

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

This ground now

The live radar over the trackEvery 2012 tornado in NebraskaEvery tornado in Nebraska since 1950Warnings in force in Nebraska nowThe forecast where you are

The other tornadoes of April 15, 2012

11 more were confirmed in the United States that day.

DateTimeRatingWherePath (mi)Width (yd)DeathsInjuriesDamage
April 155:49 AM CDTEF1Osage, OK4.2200$50,000
April 159:22 AM CDTEF1Cherokee, OK14.5500$75,000
April 1511:48 AM CDTEF0Sherman, NE0.540$60,000
April 1512:37 PM CDTEF0Valley, NE0.025
April 151:05 PM CDTEF0Wheeler, NE0.135$54,000
April 151:55 PM CDTEF0Wheeler, NE0.120
April 152:27 PM CDTEF0Knox, NE0.440
April 152:40 PM CDTEF0Bon Homme, SD0.525
April 154:11 PM CDTEF0Lyon, MN0.550
April 155:24 PM CDTEF0McLeod, MN0.115
April 156:11 PM CDTEF1Van Buren, AR2.3300$30,000

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.