Unrated tornado, Diamond to Brinton, Wyoming, July 4, 2019

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.

Rating

Unrated

Date

July 4, 2019

Touchdown

4:46 PM MDT (22:46 UTC)

Path length

0.0 miles (0.0 km)

Path width

10 yards (9 m)

Deaths

0

Injuries

0

County

Platte County

Touchdown point

41.693, -105.093

Lift-off point

41.693, -105.093

Record number

1907041646-01

Two tornadoes formed from a supercell thunderstorm moving off of the Laramie Range in southeastern Wyoming. Both tornadoes remained over open field with no discernible damage reported from NWS Storm Survey to assign any other rating but unknown. Severe thunderstorms in the area as well produced large hail up to softballs that created extensive damage in and around the Glendo area.

A supercell thunderstorm first developed over far-east central Albany County near 3:45pm MDT. This storm moved east to east-southeast into Platte County near 4:15pm MDT with increasing signs of low-level rotation per KCYS radar. The first Tornado Warning was issued at 4:32pm MDT with a report of a brief tornado touchdown by the Chugwater Fire Chief at 4:46pm MDT over rural ranch land and BLM Public Lands. With no discernible debris field or land scarring, rating assigned to unknown.

A supercell thunderstorm first developed over far-east central Albany County near 3:45pm MDT. This storm moved east to east-southeast into Platte County near 4:15pm MDT with increasing signs of low-level rotation per KCYS radar. The storm continued east-southeast with weak low-level rotation and supportive reflectivity structure. A second Tornado Warning was issued at 4:57pm MDT. Numerous reports |of funnels from chasers and storm spotters were received just after 5pm MDT. Much stronger low-level rotation developed near 5:14pm MDT via KCYS radar with confirmed tornado touchdown occurring at 5:15pm MDT. The touchdown occurred 3 miles west of |Interstate 25 west of mile marker 49. The cone tornado was observed on the ground via live-stream, pictures, and video through numerous social media channels. Tornado remained west of Interstate 25 through the entirety of its life cycle as it roped out about 1 mile west of the interstate over open ranch land. Time of dissipation is near 5:30pm MDT. Despite extensive investigation along county roads, no damage targets|were able to be identified in the open ranch land and thus an unknown EF rating was assigned.

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

14 minutes of warning. NWS CYS issued a tornado warning for this county at 22:32 UTC, 14 minutes before the tornado touched down, in force until 23:00 UTC.

The county was under a tornado watch, issued at 20:37 UTC and running to 05:53 UTC.

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 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 19:58 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 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.

The Cheyenne radar (KCYS), 65 km away, was scanning. The volume nearest the touchdown began at 22:45 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.

Local storm reports within 60 km of the path, in the three hours either side.

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

The live radar over the trackEvery 2019 tornado in WyomingEvery tornado in Wyoming since 1950Warnings in force in Wyoming nowThe forecast where you are

6 more were confirmed in the United States that day.

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.

NOAA Storm Prediction Center tornado database, 1950-2025, the official record kept by NOAA's Storm Prediction Center.