Tornadoes · United States · Nebraska · 2021

Unrated tornado, Agate, Nebraska, May 26, 2021

This Unrated tornado ran 0.4 miles across Sioux County on May 26, 2021, touching down at 4:43 PM MDT and reaching 20 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 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. Unratedthis tornado

    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
Unrated
Date
May 26, 2021
Touchdown
4:43 PM MDT (22:43 UTC)
Lifted
4:52 PM MDT (22:52 UTC)
On the ground
9 minutes
Path length
0.4 miles (0.6 km)
Path width
20 yards (18 m)
Deaths
0
Injuries
0
County
Sioux County
Touchdown point
42.410, -103.760
Lift-off point
42.413, -103.754
Record number
2105261643-01

What the Weather Service recorded

Several strong to severe thunderstorms moved across the Nebraska Panhandle producing large hail, damaging winds and a noted tornado near Agate Fossil Bed National Monument. Multiple photos and video confirmed evidence of tornado near the Agate Fossil Bed National Monument. Tornado remained over rural areas producing no discernable damage to rate other than unknown. Given sparse information and lack of damage, tornado path and width are estimates. In addition hail up to the size of baseballs were reported in the strongest storms on the 26th.

Multiple photos and video confirmed evidence of landspout tornado near the Agate Fossil Bed National Monument. Landspout remained over rural areas producing no discernable damage to rate other than unknown. Given sparse information and lack of damage, path and width are estimates.

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 19:27 UTC and running to 01:27 UTC.

Issued (UTC)ExpiredProductOffice
19:27 UTC01:27 UTCSevere Thunderstorm WatchCYS
21:08 UTC21:45 UTCSevere Thunderstorm WarningCYS
22:47 UTC23:15 UTCTornado WarningCYS
23:41 UTC00:15 UTCSevere Thunderstorm WarningCYS

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 Enhanced Risk, with a 0.05 chance of a tornado within 25 miles. The outlook in force was issued at 19:57 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.

Rapid City, SD (KUNR), 12:00Z

10.7 hours before the tornado, 198 km from the path. May 26, 2021.

Skew-T log-pSkew-T log-p diagram, Rapid City, SD at 12:00Z on 2021-05-26Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel lifted from the surface. Mixed-layer CAPE 0 joules per kilogram, CIN -106439, lifted condensation level 797 meters above ground. Wind barbs in knots down the right edge.LCL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°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, Rapid City, SD at 12:00Z on 2021-05-26The 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 48 square meters per square second, 0 to 6 km bulk shear 40 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
0 J/kg
Mixed-layer CIN
-106439 J/kg
Surface CAPE
0 J/kg
Mixed-layer LCL
797 m above ground
0-6 km bulk shear
40 kt
0-1 km bulk shear
10 kt
0-1 km storm-relative helicity
48 m²/s²
0-3 km storm-relative helicity
366 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0
0-3 km lapse rate
3.8 K/km

Open this sounding in Storm Lab

Rapid City, SD (KUNR), 00:00Z

1.3 hours after it, 198 km from the path. May 27, 2021.

Skew-T log-pSkew-T log-p diagram, Rapid City, SD at 00:00Z on 2021-05-27Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel lifted from the surface. Mixed-layer CAPE 0 joules per kilogram, CIN -106630, lifted condensation level 570 meters above ground. Wind barbs in knots down the right edge.LCL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°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, Rapid City, SD at 00:00Z on 2021-05-27The 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 370 square meters per square second, 0 to 6 km bulk shear 52 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
0 J/kg
Mixed-layer CIN
-106630 J/kg
Surface CAPE
0 J/kg
Mixed-layer LCL
570 m above ground
0-6 km bulk shear
52 kt
0-1 km bulk shear
30 kt
0-1 km storm-relative helicity
370 m²/s²
0-3 km storm-relative helicity
626 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0
0-3 km lapse rate
4.3 K/km

Open this sounding in Storm Lab

The radar

The Cheyenne radar (KCYS), 165 km away, was scanning. The volume nearest the touchdown began at 22:44 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
20:51 UTCHAIL 0.751 Nnw AgateSioux, NEHAIL FELL FROM 251 TO 255.
21:16 UTCHAIL 1.257 Ene AgateSioux, NE
21:48 UTCTSTM WND DMGFort RobinsonSioux, NEPOWER OUTAGES AT RED CLOUD CAMPGROUND AND TREE LIMB BROKEN.
22:43 UTCTORNADO1 E AgateSioux, NEUPDATED INFORMATION OF STARTING AT 443 AND LASTING FOR CLOSE TO TEN MINUTES. MULTIPLE TRAINED SPOTTER REPORTS, VIDEO, AND PICTURES CONFIRM A SHORT TORNADO TOUCH DOWN SOUTH OF THE AGATE FOSSIL BED MONUMENT. NO DAMAGE REPO
22:43 UTCTORNADO1 Ese AgateSioux, NECORRECTS PREVIOUS TORNADO REPORT FROM 1 ESE AGATE. MULTIPLE TRAINED SPOTTER REPORTS, VIDEO, AND PICTURES CONFIRM A SHORT TORNADO TOUCH DOWN SOUTH OF THE AGATE FOSSIL BED MONUMENT. NO DAMAGE REPORTED AS IT STAYED IN RURAL
23:02 UTCHAIL 11 Nnw AgateSioux, NEHAIL REPORTED FALLING FROM 502 TO 506 PM.
23:28 UTCHAIL 210 West HemingfordBox Butte, NEPHOTO ON SOCIAL MEDIA READING 2.14 INCHES FOR DIAMETER.
01:03 UTCTORNADO1 Ese AgateSioux, NEMULTIPLE TRAINED SPOTTER REPORTS, VIDEO, AND PICTURES CONFIRM A SHORT TORNADO TOUCH DOWN SOUTH OF THE AGATE FOSSIL BED MONUMENT. NO DAMAGE REPORTED AS IT STAYED IN RURAL AREAS.

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

This ground now

The live radar over the trackEvery 2021 tornado in NebraskaEvery tornado in Nebraska since 1950Warnings in force in Nebraska nowThe forecast where you are

The other tornadoes of May 26, 2021

20 more were confirmed in the United States that day.

DateTimeRatingWherePath (mi)Width (yd)DeathsInjuriesDamage
May 262:57 PM CDTUnratedEllis, KS2.5200
May 263:22 PM CDTEF0Ellis, KS0.5100
May 263:20 PM MDTUnratedDundy, NE1.650
May 263:25 PM MDTEF0Dundy, NE1.9350
May 263:39 PM MDTEF2Dundy, NE8.3575
May 263:49 PM MDTUnratedDundy, NE0.150
May 264:54 PM CDTUnratedBarton, KS0.350
May 264:01 PM MDTUnratedDundy, NE4.4300
May 265:10 PM CDTUnratedBarton, KS0.250
May 265:19 PM CDTUnratedRawlins, KS1.9200
May 265:23 PM CDTUnratedHitchcock, NE1.8100
May 265:29 PM CDTEF1Rawlins, KS3.5450
May 265:45 PM CDTUnratedRawlins, KS2.4100
May 265:56 PM CDTUnratedHansford, TX1.920
May 266:14 PM CDTUnratedHansford, TX0.820
May 266:41 PM CDTUnratedDecatur, KS1.550
May 266:49 PM CDTEF0Rice, KS0.370$25,000
May 267:34 PM CDTUnratedOchiltree, TX1.320
May 268:14 PM CDTEF0Ochiltree, TX0.920
May 269:32 PM CDTUnratedHale, TX1.030

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.