Tornadoes · United States · Wyoming · 1998

F0 tornado, Kaycee, Wyoming, June 11, 1998

This F0 tornado ran 0.1 miles across Johnson County on June 11, 1998, touching down at 12:08 PM MDT and reaching 30 yards wide. It killed nobody.

The rating scale

Tracks are drawn in the color of the rating. The Fujita scale rates the damage rather than measuring the wind: the speeds are what that damage is taken to imply.

  1. F040 to 72 mphthis tornado

    Light damage. Surface peeled off some roofs, gutters and siding damaged, branches broken, shallow-rooted trees pushed over.

  2. F173 to 112 mph

    Moderate damage. Roofs badly stripped, mobile homes overturned or badly damaged, exterior doors lost, windows broken.

  3. F2113 to 157 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. F3158 to 206 mph

    Severe damage. Whole stories of well-built houses destroyed, large buildings badly damaged, trains overturned, trees debarked, heavy cars lifted and thrown.

  5. F4207 to 260 mph

    Devastating damage. Well-built houses leveled, structures with weak foundations moved some distance, cars thrown and large missiles generated.

  6. F5261 to 318 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
F0
Date
June 11, 1998
Touchdown
12:08 PM MDT (18:08 UTC)
Path length
0.1 miles (0.2 km)
Path width
30 yards (27 m)
Deaths
0
Injuries
0
County
Johnson County
Touchdown point
43.870, -106.870
Lift-off point
43.870, -106.870
Record number
340

What the Weather Service recorded

Spotter reported that 3 funnel clouds appeared to merge into 1 and briefly touched down.

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

The warnings

23 minutes of warning. NWS RIW issued a tornado warning for this county at 17:45 UTC, 23 minutes before the tornado touched down, in force until 18:15 UTC.

Issued (UTC)ExpiredProductOffice
17:45 UTC18:15 UTCTornado WarningRIW
18:15 UTC18:45 UTCTornado WarningRIW

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 10:53 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.

Riverton, WY (KRIW), 12:00Z

6.1 hours before the tornado, 152 km from the path. June 11, 1998.

Skew-T log-pSkew-T log-p diagram, Riverton, WY at 12:00Z on 1998-06-11Temperature 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 -53065, lifted condensation level 1419 meters above ground. Wind barbs in knots down the right edge.LCL10008507005003002001001 km2 km3 km6 km9 km12 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, Riverton, WY at 12:00Z on 1998-06-11The 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 13 square meters per square second, 0 to 6 km bulk shear 8 knots.193958Sfc1 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
-53065 J/kg
Surface CAPE
0 J/kg
Mixed-layer LCL
1419 m above ground
0-6 km bulk shear
8 kt
0-1 km bulk shear
8 kt
0-1 km storm-relative helicity
13 m²/s²
0-3 km storm-relative helicity
27 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0
0-3 km lapse rate
5.9 K/km

Open this sounding in Storm Lab

Riverton, WY (KRIW), 00:00Z

5.9 hours after it, 152 km from the path. June 12, 1998.

Skew-T log-pSkew-T log-p diagram, Riverton, WY at 00:00Z on 1998-06-12Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel lifted from the surface. Mixed-layer CAPE 213 joules per kilogram, CIN -11, lifted condensation level 1564 meters above ground. Wind barbs in knots down the right edge.LCLEL10008507005003002001001 km2 km3 km6 km9 km12 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, Riverton, WY at 00:00Z on 1998-06-12The 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 16 square meters per square second, 0 to 6 km bulk shear 13 knots.1939Sfc1 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
213 J/kg
Mixed-layer CIN
-11 J/kg
Surface CAPE
1033 J/kg
Mixed-layer LCL
1564 m above ground
0-6 km bulk shear
13 kt
0-1 km bulk shear
12 kt
0-1 km storm-relative helicity
16 m²/s²
0-3 km storm-relative helicity
1 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0
0-3 km lapse rate
8.7 K/km

Open this sounding in Storm Lab

The surface observations

Worland Municipal (WRL), 87 km from the path, in the two hours either side.

Time (UTC)Temp (°F)Dew point (°F)WindGust (kt)Pressure (mb)Weather
16:51 UTC57.7448.2240° 10 kt1011.9VCSH
17:50 UTC6148.56230° 8 kt1012.2VCSH
18:52 UTC6248.74340° 5 kt1012.5VCSH
19:54 UTC61.8849.64360° 8 kt1012.2

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

This ground now

The live radar over the trackEvery 1998 tornado in WyomingEvery tornado in Wyoming since 1950Warnings in force in Wyoming nowThe forecast where you are

The other tornadoes of June 11, 1998

16 more were confirmed in the United States that day.

DateTimeRatingWherePath (mi)Width (yd)DeathsInjuriesDamage
June 111:11 AM CDTF0Cheyenne, KS0.130
June 1112:20 PM MDTF0Weston, WY0.130
June 1112:00 PM PDTF0Lyon, NV0.130
June 1112:26 PM PDTF0Lyon, NV0.130
June 115:00 PM EDTF0Montgomery, VA0.130
June 114:30 PM CDTF0Swift, MN2.550
June 116:09 PM ESTF4Hancock, IN13.24004$1.5 million
June 116:28 PM ESTF2Pulaski, IN9.01001$1.0 million
June 116:45 PM ESTF2Hancock, IN16.0300$410,000
June 117:03 PM ESTF3Howard, IN18.58008$5.5 million
June 117:20 PM ESTF0Randolph, IN5.0150$10,000
June 117:22 PM ESTF1Henry, IN11.0200$810,000
June 117:33 PM ESTF1Kosciusko, IN2.01004$800,000
June 117:41 PM ESTF1Madison, IN17.0500$2.0 million
June 119:34 PM ESTF1Wells, IN1.050$150,000
June 119:40 PM ESTF1Jay, IN2.050$300,000

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.