Tornadoes · United States · Wyoming · 2019
Unrated tornado, Diamond to Brinton, Wyoming, July 4, 2019
From Diamond to Brinton, this Unrated tornado ran 2.0 miles across Platte County on July 4, 2019, touching down at 5:16 PM MDT and reaching 200 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.
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 mph
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.
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
- July 4, 2019
- Touchdown
- 5:16 PM MDT (23:16 UTC)
- Lifted
- 5:30 PM MDT (23:30 UTC)
- On the ground
- 14 minutes
- Path length
- 2.0 miles (3.3 km)
- Path width
- 200 yards (183 m)
- Deaths
- 0
- Injuries
- 0
- County
- Platte County
- Touchdown point
- 41.683, -104.893
- Lift-off point
- 41.680, -104.854
- Record number
- 1907041716-01
What the Weather Service recorded
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.
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 Cheyenne, WY wrote its last area forecast discussion before the tornado touched down at Jul 4, 3:24 PM MDT, 1 hour 52 minutes earlier.
Area forecast discussion, Jul 4, 3:24 PM MDT, 1 hour 52 minutes before
Area Forecast Discussion
National Weather Service Cheyenne WY
324 PM MDT Thu Jul 4 2019
.SHORT TERM...(This evening through Friday)
Issued at 234 PM MDT Thu Jul 4 2019
...Severe storms expected this Afternoon and Evening...
A Tornado Watch is now in effect for much of southeast Wyoming and
north half of the Nebraska Panhandle now till 10pm MDT this
evening. Main storm hazards will be large hail up to the size of
baseballs, damaging straight-line winds of 60 to 70 mph, and a few
tornadoes will all be possible. In addition, frequent lightning,
and localized heavy rainfall will also be a concern with all the
outdoor activities on this holiday afternoon and evening. Storms
are starting to initiate in Albany County now and will shift north
and east through 11pm into the Nebraska Panhandle.
Latest meso-analysis depicts growing MLCAPE values of 2000-2500
J/Kg for the High Plains and into Albany County. Convective
inhibition has eroded enough over Albany and on the west flank of
the persistent cloud cover from this morning in Platte and
northwest Laramie County. In addition, storms will become more
robust in Converse County over the hour as well. Supportive
deep layer effective shear of of 45 to 50 knots and
climatologically lower than normal LCLs & LFCs will favor surface
boundary layer rooted rotating updrafts. Backed winds of the east
to southeast are helping yield weak to moderate low- level wind
shear initially this afternoon. However, low- level winds should
increase more into the afternoon and help support greater vertical
vorticity stretching for an increased tornado risk 4-10pm.
Storm mode will initially be discrete to semi-=discrete
supercells with a trend towards up-scale growth to clustering this
evening. Discrete cells will capable of all hazard types,
especially large hail. An upscale growth to clustering could help
focus cold pools into stronger wind hazard through the evening,
especially across Converse and Niobrara County.
Storms will shift north and east through the afternoon and evening
and diminish in coverage mostly through the evening. However,
additional clustering along a semi-organized complex could also
shift across Converse, Niobrara, into the northern Nebraska
Panhandle through 3am Friday morning.
Another round of strong to severe storms will again be possible
Friday as favorable instability and shear again combine with
southwest flow aloft ahead of a shortwave trough traversing
northern WY into the North-Central Plains. Overall coverage will
likely be lower Friday then today but high winds and large hail
could occur once again in far east WY and portions of the NE
Panhandle.
.LONG TERM...(Saturday night through Wednesday)
Issued at 238 AM MDT Thu Jul 4 2019
Continued unsettled pattern into Saturday with more afternoon and
evening storms with Sunday less active. However will make a quick
return to the storms Monday as a quick moving shortwave trough across
the central and northern Rockies. Subtle differences will need to
be monitored mid week as a H5 ridge becomes established across
the central of the CONUS. WY/NE may be just on the northeast side
of this suppressing ridge that could allow for diurnal driven
showers and thunderstorms.
&&
.AVIATION...(For the 18Z TAFS through 18Z Friday afternoon)
Issued at 1111 AM MDT Thu Jul 4 2019
Ceilings have been down to IFR at many sites this morning due to a
persistent low stratus deck. It is having difficulty eroding with
daytime heading and is still affecting KBFF and KSNY. KSNY is also
down to IFR for visibility. This should taper off by 1 PM today.
Active rest of the day across all sites. Numerous thunderstorms
will develop early this afternoon and will continue through
tonight. Some could be severe. Large hail is possible at and near
KCDR, KBFF, KAIA, and KCYS. Gusty winds will also be possible in
stronger thunderstorms. A few tornadoes cannot be ruled out, but
higher confidence is in hail today.
&&
.CYS WATCHES/WARNINGS/ADVISORIES...
WY...Flash Flood Watch until midnight MDT tonight for WYZ102-108.
NE...Flash Flood Watch until midnight MDT tonight for NEZ002-003-
019>021-095-096.
&&
SHORT TERM...JSA
LONG TERM...RUBIN
AVIATION...CWHazardous weather outlook, Jul 4, 3:29 AM MDT, 13 hours 47 minutes before
Hazardous Weather Outlook National Weather Service Cheyenne WY 329 AM MDT Thu Jul 4 2019 NEZ002-003-019>021-054-055-095-096-WYZ101>119-050930- Dawes-Box Butte-Scotts Bluff-Banner-Morrill-Kimball-Cheyenne- North Sioux-South Sioux-Converse County Lower Elevations- Niobrara County-North Laramie Range- Ferris/Seminoe/Shirley Mountains-Shirley Basin- Central Laramie Range and Southwest Platte County- East Platte County-Goshen County-Central Carbon County- North Snowy Range Foothills-Southwest Carbon County- Sierra Madre Range-Upper North Platte River Basin-Snowy Range- Laramie Valley-South Laramie Range-South Laramie Range Foothills- Central Laramie County-East Laramie County- 329 AM MDT Thu Jul 4 2019 This hazardous weather outlook is for portions of western Nebraska...east central Wyoming...south central Wyoming and southeast Wyoming. .DAY ONE...TODAY AND TONIGHT A slight to enhanced risk of severe thunderstorms exists this afternoon and evening across most of the region east of Carbon County. A Flash Flood Watch is in effect from 3 PM MDT to midnight for most of the Nebraska Panhandle as well as Niobrara and Goshen Counties of southeast Wyoming. Scattered to numerous thunderstorms will develop this afternoon and continue into the overnight hours tonight. Some of the storms will likely become severe, producing quarter size hail or larger as well as wind gusts in excess of 60 mph. Some of the thunderstorms will produce locally heavy rain and possible flash flooding due to their slow movement. .DAYS TWO THROUGH SEVEN...FRIDAY THROUGH WEDNESDAY Isolated to scattered afternoon and evening thunderstorms can be expected nearly every day. There is a marginal risk of severe thunderstorms for Friday and Saturday, as a few of the storms may become severe, producing large hail and damaging winds. .Spotter information statement... Spotter activation may be necessary this afternoon and evening. Rubin
In the hours before
Special weather statement, Jul 4, 4:08 PM MDT, 1 hour 8 minutes before
Special Weather Statement National Weather Service Cheyenne WY 408 PM MDT Thu Jul 4 2019 WYZ101-042300- Converse County Lower Elevations WY- 408 PM MDT Thu Jul 4 2019 ...SPECIAL WEATHER STATEMENT... At 407 PM MDT, Doppler radar was tracking a strong thunderstorm near Douglas, moving northeast at 25 mph. Half inch hail will be possible with this storm. This storm will remain over mainly rural areas of northeastern Converse County. A Tornado Watch remains in effect until 1000 PM MDT for east central Wyoming. LAT...LON 4279 10533 4279 10554 4324 10543 4310 10494 TIME...MOT...LOC 2207Z 212DEG 22KT 4285 10540 Lyons
Local storm report, Jul 4, 4:28 PM MDT, 48 minutes before
PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE CHEYENNE WY
428 PM MDT THU JUL 4 2019
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0420 PM FUNNEL CLOUD 10 SSW CHUGWATER 41.62N 104.90W
07/04/2019 LARAMIE WY TRAINED SPOTTER
MULTIPLE SPOTTERS REPORTING WELL DEFINED FUNNEL CLOUD
LASTING APPROXIMATELY 1 MIN
&&
WILLSLocal storm report, Jul 4, 4:37 PM MDT, 39 minutes before
PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE CHEYENNE WY
437 PM MDT THU JUL 4 2019
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0431 PM FUNNEL CLOUD 22 WNW CHUGWATER 41.88N 105.22W
07/04/2019 PLATTE WY TRAINED SPOTTER
CONTINUED REPORTS OF FUNNEL CLOUD BY MULTIPLE SPOTTERS
&&
WILLSSpecial weather statement, Jul 4, 4:49 PM MDT, 27 minutes before
Special Weather Statement National Weather Service Cheyenne WY 449 PM MDT Thu Jul 4 2019 WYZ101-103-107-042330- East Platte County WY-Converse County Lower Elevations WY- North Laramie Range WY- 449 PM MDT Thu Jul 4 2019 ...SIGNIFICANT WEATHER ADVISORY FOR NORTHERN ALBANY...NORTHWESTERN PLATTE AND SOUTH CENTRAL CONVERSE COUNTIES UNTIL 530 PM MDT... At 449 PM MDT, Doppler radar was tracking a strong thunderstorm 7 miles northwest of Esterbrook, or 20 miles south of Douglas, moving northeast at 10 mph. Half inch hail and wind gusts up to 50 mph will be possible with this storm. This storm will remain over mainly rural areas of northern Albany, northwestern Platte and south central Converse Counties. This includes Interstate 25 in Wyoming near mile marker 134. A Tornado Watch remains in effect until 1000 PM MDT for southeastern and east central Wyoming. LAT...LON 4238 10553 4247 10564 4273 10532 4252 10514 TIME...MOT...LOC 2249Z 224DEG 10KT 4246 10549 Lyons
Local storm report, Jul 4, 4:50 PM MDT, 26 minutes before
PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE CHEYENNE WY
450 PM MDT THU JUL 4 2019
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0445 PM TORNADO 13 NNE IRON MOUNTAIN 41.72N 105.10W
07/04/2019 PLATTE WY EMERGENCY MNGR
FIRE CHIEF OF CHUGWATER OBSERVED TORNADO RAIN WRAPPED
&&
WILLSLocal storm report, Jul 4, 5:01 PM MDT, 15 minutes before
<!doctype html>
<html lang="en">
<head>
<meta charset="utf-8">
<meta name="viewport" content="width=device-width, initial-scale=1">
<title>Service Notice</title>
<link rel="stylesheet" href="index.css">
</head>
<body>
<main class="wrap">
<section class="card" role="status" aria-live="polite">
<div class="status" id="status">Temporary Notice</div>
<h1 id="headline">This service is currently unavailable.</h1>
<p id="message1">
The site you requested is temporarily down for maintenance or an unexpected outage.
</p>
<p id="message2">
Please try again in a few minutes.
</p>
<p class="small" id="detail">
If you are an administrator, restore upstream service and remove the redirect/fallback rule when normal operations resume.
</p>
</section>
</main>
<script src="index.js"></script>
</body>
</html>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.
Denver, CO (KDNR), 12:00Z
11.3 hours before the tornado, 244 km from the path. July 4, 2019.
- Mixed-layer CAPE
- 8 J/kg
- Mixed-layer CIN
- -514 J/kg
- Surface CAPE
- 0 J/kg
- Mixed-layer LCL
- 2696 m above ground
- 0-6 km bulk shear
- 23 kt
- 0-1 km bulk shear
- 2 kt
- 0-1 km storm-relative helicity
- -10 m²/s²
- 0-3 km storm-relative helicity
- 26 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.0
- 0-3 km lapse rate
- 4.8 K/km
Denver, CO (KDNR), 00:00Z
0.7 hours after it, 244 km from the path. July 5, 2019.
- Mixed-layer CAPE
- 1008 J/kg
- Mixed-layer CIN
- -120 J/kg
- Surface CAPE
- 1579 J/kg
- Mixed-layer LCL
- 2132 m above ground
- 0-6 km bulk shear
- 48 kt
- 0-1 km bulk shear
- 16 kt
- 0-1 km storm-relative helicity
- 40 m²/s²
- 0-3 km storm-relative helicity
- 3 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.6
- 0-3 km lapse rate
- 8.9 K/km
The surface observations
Bordeaux (BRX), 29 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 Cheyenne radar (KCYS), 59 km away, was scanning. The volume nearest the touchdown began at 23:14 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 2019 tornado in WyomingEvery tornado in Wyoming since 1950Warnings in force in Wyoming nowThe forecast where you are
The other tornadoes of July 4, 2019
6 more were confirmed in the United States that day.
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.