Showers and thunderstorms developed in western Wyoming ahead of a cold front. SOme storms began to rotate as well.
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Deaths and injuries are direct and indirect together, as the offices filed them. Damage is property and crops in the dollars of the year, not adjusted for inflation, and only where an office estimated it.
The episode as NWS RIW wrote it up.
Showers and thunderstorms developed in western Wyoming ahead of a cold front. SOme storms began to rotate as well. In Sublette County, a funnel cloud was spotted. The funnel was photographed by several people. The funnel then dissipated before reaching the ground.
The local office's own words before the first event, 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 first event at Jun 18, 9:42 AM MST, 2 hours 14 minutes earlier.
Area Forecast Discussion National Weather Service Riverton WY 1042 AM MDT Mon Jun 18 2018 .SHORT TERM...(Today through Wednesday night The upper low remains over NW/NC NV this morning, with the trough axis neutrally-tilted. A broad area of divergence over E ID/W WY has allowed for showers and thunderstorms to continue over W WY from Sunday night. PW values are 150 to 175% above normal over the region, which is why models continue to resolve 1"+ values occurring from 03Z through 09Z Monday. Recorded rainfall amounts range between 0.30 to 0.60" since 21Z Sunday. Radar trends Sunday evening have been mainly discrete cells that pulse up and collapse within 30 minutes, but continue to develop over NE UT and move northward. Rainfall rates from PIH and SLC radars are generally 0.10"/hr, with locally higher rates up to 0.50"/hr. These higher rates have been relatively short-lived. An area of heavier rain developed over western portions of the Wind River Basin between 03Z-06Z Monday and has since lifted northward. Readings from FFMP show 1.5 to 2.5" fell along the foothills of the Wind River Mountains toward Dubois, while readings from nearby RAWS/HADS sites show 0.50 to 0.80". The exception is Crowheart, which apparently received 1.6" from 00Z to 06Z Monday. Issued a Flash Flood Warning for creeks draining toward Ethete and will keep an eye on river gauges on the Wind River from Dubois through Crowheart for now. By 12Z Monday, most of the heaviest rain will lift north out of the forecast area, with light showers continuing across western and northern portions. The front that was stationary across southern portions Sunday will lift northward as a warm front through the morning hours today. Shower and thunderstorm activity will remain confined to central and western portions, as the jet sets up from Uinta County to the Bighorn Basin. Heavier showers and thunderstorms could be possible over the Cody foothills this afternoon and evening, as the left exit region of the jet moves over the area. Temperatures east of the Divide today will be 5 to 10 degrees warmer than Sunday, but still be below normal for mid-June. Precipitation will be very isolated across the area by 12Z Tuesday, as the core of the jet continues to shift eastward. The upper low will also be over E ID and be much weaker, as it begins to fill during the day Monday. This weakening trend will continue through the day Tuesday, but will also bring enough lift to generate showers and storms across western and northern portions by late Tuesday morning and continue into the evening hours. This will spread eastward through the day and impact eastern portions by late afternoon/early evening. PW values will remain 100 to 150 percent above normal, so locally heavy rain will remain a threat. An upper level ridge will develop over CA/OR by Wednesday, as the low moves over WY and continues to weaken and get sheared apart. As elements of the subtropical jet move over SW WY, most of the shower/thunderstorm activity will be confined to areas east of the Divide (mainly east of a Cody to Casper line). Precipitation will end from northwest to southeast through the overnight hours Wednesday night. PW's will remain well above normal Wednesday. .LONG TERM...Thursday through Monday Large model differences tonight, however there is agreement that a couple systems will likely increase the shower/tstm chances across the area Thu night into the weekend. The first arrives around Thu night and swings across the north into Friday. The GFS is then more aggressive with the second system eventually forming a closed circulation over nern WY Sat. The ECMWF keeps this system much further north in MT. The GEM is similar to the GFS, just a day slower. We have some pops across the nrn two-thirds for starters, which gradually increase into Sat but if the GFS/GEM idea is more correct, we will need to increase these significantly with time. Other than the slower GEM, conditions improve next Monday with shortwave ridging developing. && .AVIATION...18Z Issuance Moisture continuing to surge northward will keep the chance of showers and thunderstorms in the forecast through 00Z Tuesday, although coverage may decrease early in the afternoon. The biggest concentration of MVFR conditions from moderate to heavy rain showers will be found west of a KLND to KWRL line this afternoon, although all areas will have a chance. There will be occasional mountain obscurations with low ceilings and reduced visibilities. Showers and thunderstorms should decrease in coverage around sunset, although showers may linger in spots through the night. Expect further showers and thunderstorms Tuesday although most will hold off until after 18Z Tuesday. Ceilings and visibilities should also improve on Tuesday. Please see the Aviation Weather Center and/or CWSU ZDV and ZLC for the latest information on icing and turbulence forecasts. && .FIRE WEATHER... Issued AT 127 AM MDT Mon Jun 18 2018 Warmer conditions across all but far western portions (which will be cooler). Scattered to numerous showers and thunderstorms will occur again today, with locally heavy rain continuing to be the main threat. Mixing and smoke dispersal will range from poor to good, with excellent conditions over portions of zones 277, 278, 279 and 289. && .RIW WATCHES/WARNINGS/ADVISORIES... Flood Watch through this evening for WYZ001>003-012-013. && SHORT TERM...LaVoie LONG TERM...Skrbac AVIATION...Hattings FIRE WEATHER...LaVoie
Hazardous Weather Outlook National Weather Service Riverton WY 207 AM MDT Mon Jun 18 2018 WYZ001>020-022>030-191200- 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- 207 AM MDT Mon Jun 18 2018 A Flood Watch remains in effect through tonight for northwest portions of Wyoming. This Hazardous Weather Outlook is for Western and Central Wyoming. .DAY ONE...Today and Tonight. Scattered to numerous showers with isolated afternoon thunderstorms through this evening, becoming isolated to scattered over northern and central portions tonight. Locally heavy rain will be possible. Snow levels around ten thousand feet over the western mountains. .DAYS TWO THROUGH SEVEN...Tuesday through Sunday. Tuesday...Scattered to numerous showers and thunderstorms. Wednesday...Isolated to scattered showers and thunderstorms for all but southern and southwestern portions. Thursday...A chance of thunderstorms in the mountains with less coverage across the lower elevations. Friday and Saturday...An increasing chance of showers and thunderstorms, especially northern and central areas. Sunday...Isolated thunderstorms possible. .SPOTTER INFORMATION STATEMENT... Spotters are urged to report hail, any flooding and wind gusts past 45 mph. Thank you.
Special Weather Statement National Weather Service Riverton WY 1208 PM MDT MON JUN 18 2018 WYZ019-030-181845- East Sweetwater County-Green Mountains and Rattlesnake Range- 1208 PM MDT MON JUN 18 2018 ...SIGNIFICANT WEATHER ADVISORY FOR SOUTHERN FREMONT AND NORTHEASTERN SWEETWATER COUNTIES UNTIL 1245 PM MDT... At 1208 PM MDT, Doppler radar was tracking a strong thunderstorm 18 miles southwest of Crooks Gap, or 24 miles southwest of Jeffrey City, moving northeast at 30 mph. Dime size hail will be possible with this storm. This strong thunderstorm will be near... Crooks Gap around 1245 PM MDT. LAT...LON 4206 10817 4222 10834 4250 10802 4228 10769 TIME...MOT...LOC 1808Z 232DEG 26KT 4220 10813 Hattings
The Riverton/Lander radar (KRIW), 146 km away, was scanning. The volume nearest the first event began at 18:54 UTC.
1 funnel cloud. Local standard time, as filed.
The Sublette County Emergency Manager reported a funnel cloud near the Big Piney airport. The funnel cloud reached about two thirds of the way to the ground but never touched down.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Wyoming in 2018Every state in 2018This day in weather historyWarnings in Wyoming, June 2018
NOAA National Centers for Environmental Information, Storm Events Database, compiled from the National Weather Service’s monthly Storm Data. Complete through 2026-06; NCEI adds each month about 75 days after it ends and revises past years a few times a year. Rebuilt 2026-09-24. Each event’s entry at NCEI: 757062.