Tornadoes · United States · Wyoming · 2023
EF1 tornado, Midwest to Columbine, Wyoming, June 23, 2023
From Midwest to Columbine, this EF1 tornado ran 10.8 miles across Natrona County on June 23, 2023, touching down at 2:15 PM MDT and reaching 100 yards wide. It killed nobody, and did $100,000 of property damage.
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 mph
Light damage. Surface peeled off some roofs, gutters and siding damaged, branches broken, shallow-rooted trees pushed over.
EF186 to 110 mphthis tornado
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
- EF1
- Date
- June 23, 2023
- Touchdown
- 2:15 PM MDT (20:15 UTC)
- Lifted
- 2:35 PM MDT (20:35 UTC)
- On the ground
- 20 minutes
- Path length
- 10.8 miles (17.4 km)
- Path width
- 100 yards (91 m)
- Deaths
- 0
- Injuries
- 0
- Property damage
- $100,000
- County
- Natrona County
- Touchdown point
- 43.300, -106.349
- Lift-off point
- 43.344, -106.142
- Record number
- 2306231415-01
What the Weather Service recorded
An upper level low passing over Wyoming combined with a strong jet stream to bring an outbreak of severe weather. Three tornadoes were confirmed in the WFO Riverton warning area on this day. This was the most in one day since June 12, 2017. There was one tornado in Sweetwater County and two in Natrona County. The largest and most impactful tornado was south of Midwest, WY in northern Natrona County where a home and surrounding property was damaged. Very large hail also occurred with some of the storms. The largest hail occurred in southern Johnson County and northern Natrona County where baseball size hail was reported from strongly rotating supercell thunderstorms. Other severe thunderstorms moved from Lander to Riverton and dropped quarter to golf ball size hail, causing damage to many roofs and vehicles.
There were numerous reports, pictures, and video of a cone tornado that touched down to the south of Midwest, WY. The tornado remained over open country for the most part. However, the tornado damaged one home where a large section of the roof was removed. Exterior walls remained standing. A trailer was overturned, fuel tanks were blown away, and trees near the residence were damaged.||Based on the FR12 damage indicator category, this tornado was rated EF1 using a low to middle end DOD estimate for the type of construction. Winds are estimated to have been around 110 mph. Stronger winds could have occurred elsewhere along the track, but open country prevented any further evidence of wind damage. Damage survey completed by county emergency management officials.
From NOAA NCEI's Storm Events Database, the narrative the local forecast office wrote for Storm Data.
What forecasters said that day
The local office's own words before the tornado touched down, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.
NWS Riverton, WY wrote its last area forecast discussion before the tornado touched down at Jun 23, 11:37 AM MDT, 2 hours 38 minutes earlier.
Area forecast discussion, Jun 23, 11:37 AM MDT, 2 hours 38 minutes before
Area Forecast Discussion National Weather Service Riverton WY 1137 AM MDT Fri Jun 23 2023 .DISCUSSION...(This afternoon through Thursday) Issued at 1135 AM MDT Fri Jun 23 2023 Summary: Active convective weather is expected today, with strong thunderstorms and a threat for damaging winds, large hail, and perhaps an isolated tornado over the Powder River Basin (Johnson and Natrona County). Other primary concerns include gusty winds for southwest and south central Wyoming, as well as a flash flooding risk with brief but very heavy thunderstorm rainfall. Given today's active weather, most of the discussion will forecast on the next 18 hours or so. Details: A well-defined shortwave will move through southwesterly flow aloft today, leading to divergence aloft, and an overall supportive environment for vertical motion. The jet streak associated with this wave is also oriented such to put central and north central Wyoming under an area of mesoscale/synoptic lift. Thunderstorms have already developed and are moving north- northeast as of late morning, and these will increase in strength as the afternoon progresses. High-resolution model averages show large pools of 1000 J/kg of CAPE, along with some pockets of up to 1500 J/kg in central Wyoming, over Johnson and Natrona County and areas further east. This ranks as one of the highest instability days so far this year for central Wyoming. Shear will be abundant as well, with 30 to 50 kt of deep layer shear in the 0-6 km layer for central and north central Wyoming. This should force storms to rotate, extending the lifespan of updrafts and support some supercells. These ingredients line up well with Storm Prediction Center forecasts for a widespread Marginal chance for severe thunderstorms, along with a Johnson County-focused Enhanced threat for large hail and damaging winds. Strong to damaging outflow winds are likely to be the most widespread issue, but large hail and an isolated tornado can't be ruled out, especially over northern Natrona and Johnson County. Very heavy rainfall is also a concern with storms this afternoon and evening, especially in the Bighorn Basin and Powder River Basin, where rainfall rates of 1 to 2 inches per hour could become common as a line of thunderstorms moves through. PW values are above normal, with the morning Riverton sounding showing 134 percent of normal moisture available, and models show areas of over 0.75 inches of PW in the Bighorn, Wind River, and Powder River Basin. Local communities where there are a lot of impermeable surfaces will be the focus for flash flooding threats, but ponding of water and minor flooding issues are possible even outside of population centers. There is a Marginal to Slight risk for Excessive Rainfall per the Weather Prediction Center. Timing-wise, the stronger storms are likely to move through the Wind River Basin between now (1130 AM) and 6 PM MDT, the Bighorn Basin between 1 and 7 PM, and the Powder River Basin between 2 and 8 PM. Thunderstorms decrease notably after sunset this evening. Rain will continue across northern Wyoming. Expect river and stream flows to increase in the coming couple days across northern Wyoming especially, given recent rain and high-elevation snowmelt making its way through the river system. Winds will remain breezy on Saturday, with gusts 30 to 40 mph possible in the typical wind corridor from Sweetwater to Natrona County. The flow turns more zonal on Saturday, with a notably decreased thunderstorm threat. On Sunday, southwest flow returns, with scattered showers and thunderstorms again possible. This southwest flow patterns continues through the middle of next week. Models diverge for the second half of the week, and differ on how quickly they move another shortwave trough through the region. Have stuck with consensus model guidance for this portion of the extended forecast. && .AVIATION...(For the 18Z TAFS through 18Z Saturday) Issued at 1102 AM MDT Fri Jun 23 2023 Showers and thunderstorms continue to develop and spread across the area this afternoon. Most terminals begin the period with VCTS with the remainder seeing VCTS by 21Z. Showers and thunderstorms continue into the evening with stronger storms expected east of the Divide. Winds may become gusty at times this afternoon with gusts between 25 to 35 knots. Depending on the location of stronger storms gusts, over 50 knots can not be ruled out. Some storms may create periods of MVFR/IFR due to heavy rain. Frequent lightning along with small hail is also a threat with any storm. Thunderstorms begin to dissipate during the evening with light to moderate rain showers lingering over northern Wyoming terminals overnight. By Friday morning VFR conditions are expected to prevail through the end of the period. A few terminals may see some lingering MVFR ceilings but ceilings will improve by the late morning. Winds begin to increase during the morning with gusts between 20 to 30 knots possible at some terminals come the end of the period. Please see the Aviation Weather Center and/or CWSU ZDV and ZLC for the latest information on smoke, icing, and turbulence forecasts. && .FIRE WEATHER... Issued at 218 AM MDT Fri Jun 23 2023 Low pressure will move across Wyoming and bring showers and thunderstorms, most numerous in the afternoon and evening and across northern Wyoming. Some storms could become strong to severe with large hail, strong winds and possibly a tornado. Heavy rain is also possible with any storm with a wetting possible. In southern Wyoming, strong wind will develop this afternoon with wind gusts past 40 mph at times. Relative humidity will fall below 15 percent across portions of Sweetwater County, otherwise it will remain above critical levels. Mixing and smoke dispersal will range from fair to good across the north to excellent across southern Wyoming. && .RIW WATCHES/WARNINGS/ADVISORIES... NONE. && DISCUSSION...VandenBoogart AVIATION...Dziewaltowski FIRE WEATHER...Hattings
Hazardous weather outlook, Jun 23, 2:28 AM MDT, 11 hours 47 minutes before
Hazardous Weather Outlook National Weather Service Riverton WY 228 AM MDT Fri Jun 23 2023 WYZ001>020-022>030-241300- Yellowstone National Park-Absaroka Mountains-Cody Foothills- North Big Horn Basin-Southwest Big Horn Basin- Southeast Big Horn Basin-Owl Creek and Bridger Mountains- Bighorn Mountains West-Bighorn Mountains Southeast- Northeast Johnson County-Southeast Johnson County- Teton and Gros Ventre Mountains-Jackson Hole- Wind River Mountains West-Wind River Mountains East- Upper Wind River Basin-Wind River Basin-Lander Foothills- Green Mountains and Rattlesnake Range- Natrona County Lower Elevations-Casper Mountain-Star Valley- Salt River and Wyoming Ranges-Upper Green River Basin Foothills- Upper Green River Basin-South Lincoln County- Rock Springs and Green River-Flaming Gorge-East Sweetwater County- 228 AM MDT Fri Jun 23 2023 This Hazardous Weather Outlook is for Western and Central Wyoming. .DAY ONE...Today and tonight. Showers and thunderstorms developing later this morning and continuing into tonight. Some storms may become severe with large hail, damaging wind and even an isolated tornado. The best chance of severe thunderstorms will be in Big Horn, Washakie, Natrona and especially Johnson County. All areas East of the Divide will have a chance of stronger storms though. Strong wind developing this afternoon across Sweetwater County. .DAYS TWO THROUGH SEVEN...Saturday through Thursday. Saturday through Thursday...Daily chances of mainly afternoon and evening thunderstorms, especially in northern Wyoming. .SPOTTER INFORMATION STATEMENT... Weather spotters are encouraged to report significant weather conditions according to Standard Operating Procedures.
In the hours before
Special weather statement, Jun 23, 12:19 PM MDT, 1 hour 56 minutes before
Special Weather Statement
National Weather Service Riverton WY
1219 PM MDT Fri Jun 23 2023
WYZ027-231845-
South Lincoln County-
1219 PM MDT Fri Jun 23 2023
...A strong thunderstorm will impact portions of south central
Lincoln County through 1245 PM MDT...
At 1219 PM MDT, Doppler radar was tracking a strong thunderstorm 8
miles south of Elkol, which is also 12 miles south of Kemmerer,
moving north at 20 mph.
HAZARD...Winds in excess of 30 mph and penny size hail.
SOURCE...Radar indicated.
IMPACT...Gusty winds could knock down tree limbs and blow around
unsecured objects. Minor damage to outdoor objects is
possible.
Locations impacted include...
Elkol, Kemmerer and Diamondville.
PRECAUTIONARY/PREPAREDNESS ACTIONS...
If outdoors, consider seeking shelter inside a building.
Very heavy rainfall is also occurring with this storm and may lead
to localized flooding. Do not drive your vehicle through flooded
roadways.
&&
LAT...LON 4184 11066 4185 11064 4183 11063 4182 11061
4183 11060 4186 11060 4182 11028 4158 11043
4158 11071
TIME...MOT...LOC 1819Z 201DEG 17KT 4160 11057
MAX HAIL SIZE...0.75 IN
MAX WIND GUST...30 MPH
McDonaldLocal storm report, Jun 23, 12:39 PM MDT, 1 hour 36 minutes before
Preliminary Local Storm Report
National Weather Service Riverton WY
1239 PM MDT Fri Jun 23 2023
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
1202 PM Hail 4 W Riverton 43.03N 108.46W
06/23/2023 M1.00 inch Fremont WY NWS Employee
1202 PM Hail 6 WNW Riverton 43.07N 108.48W
06/23/2023 M1.00 inch Fremont WY NWS Employee
1205 PM Hail 2 W Riverton 43.03N 108.42W
06/23/2023 M1.25 inch Fremont WY NWS Employee
1205 PM Hail 1 NE Riverton 43.03N 108.37W
06/23/2023 M2.00 inch Fremont WY CO-OP Observer
1205 PM Hail 1 W Riverton 43.03N 108.39W
06/23/2023 M1.75 inch Fremont WY NWS Employee
1205 PM Hail 1 NNE Riverton 43.04N 108.37W
06/23/2023 M1.75 inch Fremont WY Public
1205 PM Hail 1 WSW Riverton 43.02N 108.39W
06/23/2023 M1.25 inch Fremont WY NWS Employee
&&Special weather statement, Jun 23, 12:44 PM MDT, 1 hour 31 minutes before
Special Weather Statement
National Weather Service Riverton WY
1244 PM MDT Fri Jun 23 2023
WYZ027-028-231915-
South Lincoln County-Rock Springs and Green River-
1244 PM MDT Fri Jun 23 2023
...A strong thunderstorm will impact portions of southeastern Lincoln
and west central Sweetwater Counties through 115 PM MDT...
At 1244 PM MDT, Doppler radar was tracking a strong thunderstorm 10
miles south of Opal, which is also 17 miles west of Granger, moving
northeast at 30 mph.
HAZARD...Winds in excess of 30 mph and penny size hail.
SOURCE...Radar indicated.
IMPACT...Gusty winds could knock down tree limbs and blow around
unsecured objects. Minor damage to outdoor objects is
possible.
This strong thunderstorm will be near...
Opal around 100 PM MDT.
This includes Interstate 80 between mile markers 57 and 60.
PRECAUTIONARY/PREPAREDNESS ACTIONS...
If outdoors, consider seeking shelter inside a building.
Very heavy rainfall is also occurring with this storm and may lead
to localized flooding. Do not drive your vehicle through flooded
roadways.
Frequent cloud to ground lightning is occurring with this storm.
Lightning can strike 10 miles away from a thunderstorm. Seek a safe
shelter inside a building or vehicle.
This storm may intensify, so be certain to monitor local radio
stations and available television stations for additional information
and possible warnings from the National Weather Service.
&&
LAT...LON 4197 11042 4186 10989 4184 10987 4184 10980
4143 11004 4143 11005 4158 11005 4158 11051
TIME...MOT...LOC 1844Z 203DEG 27KT 4162 11029
MAX HAIL SIZE...0.75 IN
MAX WIND GUST...30 MPH
McDonaldSpecial weather statement, Jun 23, 1:15 PM MDT, 1 hour before
Special Weather Statement
National Weather Service Riverton WY
115 PM MDT Fri Jun 23 2023
WYZ026>028-231945-
Upper Green River Basin-South Lincoln County-Rock Springs and Green
River-
115 PM MDT Fri Jun 23 2023
...A strong thunderstorm will impact portions of southeastern Lincoln
and west central Sweetwater Counties through 145 PM MDT...
At 114 PM MDT, Doppler radar was tracking a strong thunderstorm near
Granger, moving east at 40 mph.
HAZARD...Winds in excess of 30 mph and penny size hail.
SOURCE...Radar indicated.
IMPACT...Gusty winds could knock down tree limbs and blow around
unsecured objects. Minor damage to outdoor objects is
possible.
This storm will remain over mainly rural areas of southeastern
Lincoln and west central Sweetwater Counties.
This includes Interstate 80 between mile markers 62 and 90.
PRECAUTIONARY/PREPAREDNESS ACTIONS...
If outdoors, consider seeking shelter inside a building.
Very heavy rainfall is also occurring with this storm and may lead
to localized flooding. Do not drive your vehicle through flooded
roadways.
Frequent cloud to ground lightning is occurring with this storm.
Lightning can strike 10 miles away from a thunderstorm. Seek a safe
shelter inside a building or vehicle.
This storm may intensify, so be certain to monitor local radio
stations and available television stations for additional information
and possible warnings from the National Weather Service.
&&
LAT...LON 4158 11005 4158 11009 4178 11019 4192 10958
4153 10941 4151 11005
TIME...MOT...LOC 1914Z 258DEG 33KT 4165 10992
MAX HAIL SIZE...0.75 IN
MAX WIND GUST...30 MPH
McDonaldLocal storm report, Jun 23, 1:49 PM MDT, 26 minutes before
Preliminary Local Storm Report
National Weather Service Riverton WY
149 PM MDT Fri Jun 23 2023
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
1245 PM Hail 2 N Lysite 43.28N 107.71W
06/23/2023 E2.00 inch Fremont WY Public
&&Local storm report, Jun 23, 2:14 PM MDT, 1 minute before
Preliminary Local Storm Report
National Weather Service Riverton WY
214 PM MDT Fri Jun 23 2023
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0135 PM Tornado 9 NE Granger 41.68N 109.86W
06/23/2023 Sweetwater WY Public
&&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
8.3 hours before the tornado, 177 km from the path. June 23, 2023.
- Mixed-layer CAPE
- 26 J/kg
- Mixed-layer CIN
- -247 J/kg
- Surface CAPE
- 402 J/kg
- Mixed-layer LCL
- 1054 m above ground
- 0-6 km bulk shear
- 37 kt
- 0-1 km bulk shear
- 3 kt
- 0-1 km storm-relative helicity
- -17 m²/s²
- 0-3 km storm-relative helicity
- 110 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- -0.0
- 0-3 km lapse rate
- 5.2 K/km
The surface observations
Casper/Natrona International (CPR), 49 km from the path, in the two hours either side.
| Time (UTC) | Temp (°F) | Dew point (°F) | Wind | Gust (kt) | Pressure (mb) | Weather |
|---|---|---|---|---|---|---|
| 00:00 UTC |
From the Iowa Environmental Mesonet's archive of airport observations.
The radar
The Riverton/Lander radar (KRIW), 183 km away, was scanning. The volume nearest the touchdown began at 20:14 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.
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 23, 2023
23 more were confirmed in the United States that day.
| Date | Time | Rating | Where | Path (mi) | Width (yd) | Deaths | Injuries | Damage |
|---|---|---|---|---|---|---|---|---|
| June 23 | 12:30 PM MDT | EF0 | Caribou, ID | 0.2 | 10 | |||
| June 23 | 1:35 PM MDT | Unrated | Sweetwater, WY | 0.1 | 30 | |||
| June 23 | 2:37 PM MDT | Unrated | Natrona, WY | 0.7 | 50 | |||
| June 23 | 4:33 PM MDT | Unrated | Converse, WY | 0.3 | 50 | |||
| June 23 | 5:11 PM MDT | Unrated | Platte, WY | 0.0 | 50 | |||
| June 23 | 5:29 PM MDT | Unrated | Goshen, WY | 3.0 | 50 | |||
| June 23 | 5:40 PM MDT | EF3 | Prowers, CO | 13.1 | 320 | |||
| June 23 | 5:49 PM MDT | EF2 | Campbell, WY | 3.8 | 800 | 8 | ||
| June 23 | 6:03 PM MDT | Unrated | Goshen, WY | 0.5 | 50 | |||
| June 23 | 6:21 PM MDT | EF2 | Goshen, WY | 4.7 | 800 | 1 | $100,000 | |
| June 23 | 6:33 PM MDT | EF1 | Baca, CO | 8.4 | 100 | |||
| June 23 | 6:44 PM MDT | EF1 | Goshen, WY | 3.9 | 20 | |||
| June 23 | 6:45 PM MDT | EF0 | Weston, WY | 6.0 | 200 | |||
| June 23 | 7:04 PM MDT | Unrated | Scotts Bluff, NE | 3.5 | 50 | |||
| June 23 | 7:22 PM MDT | Unrated | Scotts Bluff, NE | 3.2 | 50 | |||
| June 23 | 7:38 PM MDT | EF2 | Scotts Bluff, NE | 2.5 | 700 | $135,000 | ||
| June 23 | 8:40 PM CDT | EF0 | Stanton, KS | 0.0 | 1 | |||
| June 23 | 7:44 PM MDT | EF1 | Scotts Bluff, NE | 1.2 | 50 | |||
| June 23 | 7:50 PM MDT | Unrated | Scotts Bluff, NE | 0.5 | 50 | |||
| June 23 | 8:05 PM MDT | Unrated | Scotts Bluff, NE | 0.5 | 50 | |||
| June 23 | 9:09 PM CDT | EF0 | Stanton, KS | 0.0 | 1 | |||
| June 23 | 9:12 PM CDT | EF0 | Grant, KS | 4.2 | 1 | |||
| June 23 | 9:51 PM MDT | Unrated | Morrill, NE | 0.5 | 50 |
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.