A shower collapsed near the Natrona County airport and produced a dry microburst. Winds gusted as high as 70 mph.
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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.
A shower collapsed near the Natrona County airport and produced a dry microburst. Winds gusted as high as 70 mph. No damage was reported.
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 5, 1:00 PM MST, 5 hours 35 minutes earlier.
Area Forecast Discussion National Weather Service Riverton WY 200 PM MDT Tue Jun 5 2018 .SHORT TERM...(This evening through Friday) Issued at 156 PM MDT Tue Jun 5 2018 |THE RIDGE AXIS HAS MOVED OFF TO THE EAST PLACING US UNDER THE SOUTHWEST STEERING FLOW. A SHORTWAVE WILL BE TRACKING NORTHEAST WITHIN THE SOUTHWEST FLOW FOR THE REST OF TODAY. THIS SHORTWAVE WILL EJECT A WEAK COLD FRONT SOUTH ACROSS NORTHERN WYOMING LATER THIS AFTERNOON. ALONG AND BEHIND THE FRONT, LIFTED INDICES WILL DROP TO -6.5 ACROSS JOHNSON COUNTY ALONG WITH HIGHER CAPES WHERE THE BEST CHANCE OF SIGNIFICANT THUNDERSTORM ACTIVITY WILL OCCUR THIS EVENING, ALONG WITH A CHANCE OF LESSER STORM ACTIVITY ACROSS THE REST OF THE NORTH. TONIGHT, THE FRONT WILL DRIFT SOUTH TO ALMOST THE DIVIDE. HIGHER DEW POINTS WILL POOL NORTHEAST OF THE FRONT. CURRENTLY, WEST OF THE DIVIDE, DEW POINTS ARE IN THE 30S, 40S IN CENTRAL WYOMING EAST OF THE DIVIDE, AND IN THE LOW TO MID 50S IN THE BIG HORN BASIN AND IN JOHNSON COUNTY. THESE HIGHER DEW POINTS WILL DRIFT SOUTH WITH THE FRONT. ON WEDNESDAY, SURFACE WINDS WILL VEER TO THE SOUTHEAST BEHIND THE FRONT WITH A SFC LOW EXTENDING UP TO 700MB DEVELOPING OVER SOUTHWEST WYOMING ENHANCING THE SFC SOUTHEASTERLY FLOW, AIDING IN DRAWING IN MORE SFC MSTR AS WELL AS INCREASING THE DIRECTIONAL SHEER. 850 MB WINDS ARE PROGGED TO BE SOUTHERLY AT 20 KNOTS OVER NATRONA CO. SPC HAS NOW SHIFTED THE SLIGHT RISK AREA WEST ON WEDNESDAY TO INCLUDE A BIG SWATH OF CENTRAL WYOMING EAST OF THE DIVIDE TO INCLUDE CODY, WORLAND, BUFFALO, AND JUST BARELY RIVERTON. LANDER AND CASPER ARE NOT TECHNICALLY IN THE SLIGHT RISK AREA FOR WHAT ITS WORTH. IN ADDITION, WE WILL BE UNDERNEATH THE RRQ OF THE ASCT JET MAX. THE GFS HAS BYG/CPR CAPES UP AROUND 1500 WITH LESSER CAPES TO THE WEST. THE STRONGEST ACTIVITY APPEARS THAT IT WILL PROPAGATE SOUTH WITH TIME, ALTHOUGH THE CELLS WILL RACE TO THE NORTHEAST. THE STRONG CONVECTIVE ACTIVITY WILL LIKELY BE A RELATIVELY LATE SHOW WITH THE POST FRONTAL INVERSION CAP NEEDING TO BE BROKEN, ALONG WITH THE ENHANCING VORT LOBE TRACKING NORTHEAST ACROSS THE AREA AROUND 00Z AS IT BISECTS THE FRONTAL BOUNDARY, ALONG WITH ANOTHER LESSER VORT LOBE DUE TO COME THROUGH AROUND 06Z THURSDAY. MORE WIDELY SCATTERED GARDEN VARIETY THUNDERSHOWERS ARE PROGGED FOR AREAS WEST OF THE DIVIDE WEDNESDAY. THE ONE THING THAT COULD GO WRONG WITH THE FORECAST IS THE CAP MAY BE TOO STRONG AND DELAY THE CONVECTIVE ACTIVITY, ESPECIALLY IN OUR EASTERN ZONES, BUT FOR NOW, CONDITIONS LOOK FAVORABLE FOR AN ACTIVE WEATHER DAY WEDNESDAY. ON THURSDAY, THE FRONT WILL RETREAT NORTHEAST WITH THE STRONGEST THUNDERSTORM ACTIVITY RELEGATED TO JOHNSON COUNTY WHERE LIFTED INDICES ARE PROGGED TO BE -7 ALONG WITH THE HIGHER CAPES WITHIN THE "RING OF FIRE" NORTH OF THE BUILDING UPPER HIGH OVER THE SOUTH CENTRAL PORTION OF THE COUNTRY. FRIDAY WILL BE WARM AND DRY AS THE HIGH CONTINUES TO BUILD NORTH. .LONG TERM...(Wednesday night through Tuesday) Issued at 156 PM MDT Tue Jun 5 2018 Warm ridge axis just to our east through Saturday ahead of a negatively tilted trough. This trough will impact the nwrn corner on Sunday with the potential for strong to svr tstms. Quite warm ahead of this system with increasing s-sw wind. Fire wx threat will increase also ahead of this trough (very warm/hot, dry and windy) over the weekend. Cooler behind this system Monday but still quite dry with low rh's once again and breezy conds. Tuesday will start to see a rebound in temperatures with breezy areas. && .AVIATION...(For the 00Z TAFS through 00Z Wednesday evening) Issued at 156 PM MDT Tue Jun 5 2018 Isold showers and thunderstorms are possible across mainly the far north thru 02z with KCOD having the best shot for terminal sites. A weak cold front will slide south overnight with low clouds and lcl MVFR conds from KCPR to KBYG after 09z through 15z. Thunderstorms will be on the increase Wednesday afternoon and evening. Some of these may be quite strong to severe along and east of the divide. && .FIRE WEATHER... Issued AT 156 PM MDT Tue Jun 5 2018 A weak cold front will stall across northern portions of the state this evening. Isolated thunderstorms may fire across the northern third of the state, but a vast majority of the area should remain dry. A gusty southwest breeze will continue south of the front. Mixing and smoke dispersal will range from fair to poor over the northern basins to excellent across southern Wyoming. Thunderstorm activity will increase Wednesday (as the front moves southwest to near the divide) especially east of the divide where some storms could be relatively strong. Zones 277-278-279 will have a minimum RH of 10 to 15 percent Wednesday. Most of zone 279 will be precip free Wednesday. Mixing and smoke dispersal will likely improve over the north and northeast as the frontal inversion breaks, otherwise mixing and smoke dispersal remaining excellent. && .RIW WATCHES/WARNINGS/ADVISORIES... NONE. && SHORT TERM...Lipson LONG TERM...Skrbac AVIATION...Skrbac FIRE WEATHER...Lipson
Hazardous Weather Outlook National Weather Service Riverton WY 202 AM MDT Tue Jun 5 2018 WYZ001>020-022>030-061315- 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- 202 AM MDT Tue Jun 5 2018 This Hazardous Weather Outlook is for Western and Central Wyoming. .DAY ONE...Today and Tonight Isolated afternoon and evening thunderstorms in northern Wyoming. .DAYS TWO THROUGH SEVEN...Wednesday through Monday Wednesday...Isolated to scattered thunderstorms, especially in the north and east. Strong to possibly severe thunderstorms are possible, especially in the Big Horn Basin as well as Johnson and Natrona Counties. Thursday...Isolated to widely scattered thunderstorms over northern and central areas. A few strong thunderstorms possible mainly over the Big Horn Basin and Johnson County. Friday...Isolated afternoon and evening thunderstorms mainly over the north, along the lee side of mountain ranges and adjacent foothills. .SPOTTER INFORMATION STATEMENT... Spotters are urged to report wind gusts over 45 mph and hail. Thank you. TEAM RIVERTON
The Riverton/Lander radar (KRIW), 164 km away, was scanning. The volume nearest the first event began at 01:34 UTC.
1 thunderstorm wind. Local standard time, as filed.
The ASOS at the Natrona County airport reported a maximum wind gust of 70 mph.
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: 756954.