Tornadoes · United States · Wyoming · 2023

Unrated tornado, Chugwater, Wyoming, June 22, 2023

This Unrated tornado ran 3.1 miles across Platte County on June 22, 2023, touching down at 4:42 PM MDT 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.

  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
June 22, 2023
Touchdown
4:42 PM MDT (22:42 UTC)
Lifted
4:45 PM MDT (22:45 UTC)
On the ground
3 minutes
Path length
3.1 miles (5.0 km)
Path width
50 yards (46 m)
Deaths
0
Injuries
0
County
Platte County
Touchdown point
41.653, -104.879
Lift-off point
41.644, -104.820
Record number
2306221642-01

What the Weather Service recorded

Severe storms developed across the southeast Wyoming high plains the afternoon of 22 June 2023. Storms produced heavy rain resulting in flash flooding for parts of the plains and a tornado near Chugwater, Wyoming.

Public report of a tornado touchdown 8 miles south southwest of Chugwater that lasted roughly 3 minutes. No damage reported.

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

The warnings

23 minutes of warning. NWS CYS issued a tornado warning for this county at 22:19 UTC, 23 minutes before the tornado touched down, in force until 22:45 UTC.

The county was under a severe thunderstorm watch, issued at 18:15 UTC and running to 02:50 UTC.

Issued (UTC)ExpiredProductOffice
18:15 UTC02:50 UTCSevere Thunderstorm WatchCYS
21:10 UTC00:15 UTCFlood AdvisoryCYS
21:44 UTC22:30 UTCSevere Thunderstorm WarningCYS
22:19 UTC22:45 UTCTornado WarningCYS
22:43 UTC23:12 UTCSevere Thunderstorm WarningCYS
23:10 UTC04:15 UTCFlash Flood WarningCYS
00:48 UTC04:00 UTCFlood AdvisoryCYS
04:14 UTC05:00 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 Slight Risk, with a 0.02 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.

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

10.7 hours before the tornado, 313 km from the path. June 22, 2023.

Skew-T log-pSkew-T log-p diagram, Rapid City, SD at 12:00Z on 2023-06-22Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel lifted from the surface. Mixed-layer CAPE 29 joules per kilogram, CIN -276, lifted condensation level 798 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, Rapid City, SD at 12:00Z on 2023-06-22The 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 -20 square meters per square second, 0 to 6 km bulk shear 31 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
29 J/kg
Mixed-layer CIN
-276 J/kg
Surface CAPE
77 J/kg
Mixed-layer LCL
798 m above ground
0-6 km bulk shear
31 kt
0-1 km bulk shear
2 kt
0-1 km storm-relative helicity
-20 m²/s²
0-3 km storm-relative helicity
27 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.1
0-3 km lapse rate
4.1 K/km

Open this sounding in Storm Lab

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

1.3 hours after it, 313 km from the path. June 23, 2023.

Skew-T log-pSkew-T log-p diagram, Rapid City, SD at 00:00Z on 2023-06-23Temperature 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 -43852, lifted condensation level 927 meters above ground. Wind barbs in knots down the right edge.LCL10008507005003002001001 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, Rapid City, SD at 00:00Z on 2023-06-23The 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 10 square meters per square second, 0 to 6 km bulk shear 33 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
-43852 J/kg
Surface CAPE
116 J/kg
Mixed-layer LCL
927 m above ground
0-6 km bulk shear
33 kt
0-1 km bulk shear
2 kt
0-1 km storm-relative helicity
10 m²/s²
0-3 km storm-relative helicity
85 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

The radar

The Cheyenne radar (KCYS), 55 km away, was scanning. The volume nearest the touchdown began at 22:39 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
22:32 UTCTORNADO8 Ssw ChugwaterPlatte, WY
00:38 UTCFLASH FLOOD5 S YoderGoshen, WYWater covering sidewalk, street and yard.
01:39 UTCFLASH FLOODChugwaterPlatte, WYFlooding of some roads and some roads are impassable.

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

This ground now

The live radar over the trackEvery 2023 tornado in WyomingEvery tornado in Wyoming since 1950Warnings in force in Wyoming nowThe forecast where you are

The other tornadoes of June 22, 2023

4 more were confirmed in the United States that day.

DateTimeRatingWherePath (mi)Width (yd)DeathsInjuriesDamage
June 221:04 PM EDTEF1Lenoir, NC0.7100
June 223:41 PM CDTEF1Hemphill, TX10.3150$85,000
June 223:24 PM MDTEF1Douglas, CO6.325
June 228:08 PM MDTEF0El Paso, CO0.810

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.