An isolated thunderstorm moved out of Idaho and into Yellowstone Park. A park ranger reported penny size hail at Madison Junction.
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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.
An isolated thunderstorm moved out of Idaho and into Yellowstone Park. A park ranger reported penny size hail at Madison Junction.
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 6, 10:43 AM MST, 3 hours 2 minutes earlier.
Area Forecast Discussion National Weather Service Riverton WY 1143 AM MDT Thu Jun 6 2019 .SHORT TERM...Today through Friday night A low pressure center spinning on the British Columbia Coast and the associated prominent trough will be approaching the CWA today. As it draws closer to the area, the pressure gradient will increase resulting in increase shear, especially in Far Western and Northwest Wyoming today under difluent flow. In addition, there will be sufficient cape in those areas. This, among other parameters, has prompted SPC to put our far western zones in a slight risk for this afternoon. Meanwhile. Our central and eastern zones will experience some southwest breezes along with the warmest and driest day of the season thus far. High temperatures could approach 90 degrees in the Big Horn Basin this afternoon for the first time this year. Many areas will experience the warmest temperatures thus far this season with high temperatures well up into the 80s in many areas east of the Divide and 70s west. For Friday, the closed low will track east across Southern Canada and will sling the associated trailing trough across the Pacific Northwest and Great Basin. As the trough nears, southwest winds will increase across much of the area with gusts of 40 to 50 mph common. The sfc and 700mb gradient does not look impressive for Friday ahead of the front, but 700mb 40 knot winds will surface, elevating our surface pre frontal southwest winds. The best capes will be relegated to Johnson County for Friday afternoon with SPC putting northeast Johnson County under slight risk. As the front approaches, numerous showers and thunderstorms will likely occur over the west and the rest of the northern zones, just not as strong as the storms in Johnson County. Part two of the winds will occur later in the afternoon and evening behind the front with three hourly sfc pressure rises of 9mb along with 13mb pressure rises over Johnson County, with 40 plus mph northwest wind gusts certainly a probability. Then for Friday night, numerous showers and thunderstorms will be relegated to mainly Northern Wyoming, closer to the track of the low center. QG forcing will aid in lift. After midnight, the threat of thunder will be gone and we will just be left with frequent showers. Snow levels will drop all the way down to the lowest elevations of Yellowstone Park where 2 to 3 inches of snow is expected Friday night. In the Big Horn Mountains, snow levels should drop to about 7000 feet. At elevations above 9000 feet in the Tetons and Wind River Mountains, 1 to 2 inches of snow is likely. .LONG TERM...Saturday through Thursday The cold front will have moved through the whole area by 12Z Saturday. Thus a much cooler day across the region. The upper level trough with colder air aloft will still have to pass through WY on Saturday. Models hold on to scattered showers and a few storms Saturday into Saturday evening. Steeper lapse rates along with some moisture and instability will aid in the showers or storms over the north with less coverage in the central zones. The south looks dry. Convection ends toward late Saturday evening. Low temps Saturday night will drop into the 30s east of the divide, but not looking at freezing temps for now. Expect some lows in the 20s in the western valleys. Sunday looks dry for most places. Isolated showers or storms are possible in the northern mountains in the afternoon and evening. Mild high temps on Sunday. Monday looks dry and warmer over the region. On Tuesday, a possible weak weather system may clip NE WY during the day into the evening. This could lead to isolated showers or storms in the northern mountains and Johnson county for Tuesday afternoon into the evening. Dry elsewhere Tuesday. Expect high temps to be slightly warmer Tue. Wednesday looks dry and warmer for the area. Maybe isolated mountain showers or storms in the central and northern mountains. Next Thursday looks to be warmer as well. Isolated showers and storms will occur in the afternoon and evening. && .AVIATION...For the 18Z TAFS through 18Z Friday Showers and thunderstorms are increasing in the west and KJAC already has vicinity thunderstorms. Some storms could become strong to severe with strong wind gusts and hail west of a KEMM-KDUB-KCOD line after 19Z. Showers and thunderstorms will then progress eastward to many TAF sites through 06Z, with the exception of KCPR. Though still uncertain, models have placed some shower activity near KWRL so have placed VCSH in between 04Z-06Z. Local MVFR and IFR conditions will be likely in and around of any shower or thunderstorm, especially between 20Z and 04Z Friday. Most thunderstorms will end by 05Z Friday, but showers will remain possible through 12Z Friday in some of the TAF sites west of the Divide. && .FIRE WEATHER... Marginally elevated fire conditions will be in place today. Portions of zones 275, 279, 282 and 283 will have RH values in the mid to upper teens this afternoon. The strongest winds today, with gusts over 25 mph, will occur over wind prone locations from 277 to 280. Today will likely be the warmest and driest day of the season thus far. However, with wind speeds remaining below thresholds most areas, fire danger should remain in check, considering we are in full green up. A strong Pacific trough will begin to approach the area from the west today which will initiate fairly strong thunderstorm activity in the far wet and northwest zones today. On Friday, the associated cold front will approach the area. Fairly brisk southwest winds, some with gusts of 40 to 50 mph, will blow ahead of the approaching front Friday. The low relative humidity expected this afternoon will not coincide with the stronger winds on Friday. Temperatures will still be fairly warm in the central and east Friday. Fairly strong thunderstorms are possible in zone 281 Friday. Numerous showers and thunderstorms are expected across the rest of the north and west Friday, but just not as strong as the ones in zone 281. As the front pushes through later on Friday, veering northwest wind gusts of over 40 mph are expected in many areas along with sharply colder temperatures by Friday evening. Snow levels will lower. In fact. zone 140 could see 2 to 3 inches of snow Friday night with elevations above 9000 feet in zones 415 and 288 seeing 1 to 2 inches of snow. && .RIW WATCHES/WARNINGS/ADVISORIES...NONE. && SHORT TERM...Lipson LONG TERM...AR AVIATION...Hattings/Bourque FIRE WEATHER...Lipson
Hazardous Weather Outlook National Weather Service Riverton WY 349 AM MDT Thu Jun 6 2019 WYZ001>020-022>030-071200- 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- 349 AM MDT Thu Jun 6 2019 This Hazardous Weather Outlook is for Western and Central Wyoming. .DAY ONE...Today and Tonight Scattered thunderstorms in the west. A few thunderstorms could be strong to severe over the west late in the afternoon into the evening hours. .DAYS TWO THROUGH SEVEN...Friday through Wednesday Warm temperatures Thursday and Friday will continue the higher elevation snowmelt resulting in rising water levels in creeks, streams, and rivers into this weekend. Friday...A chance of thunderstorms west and north. Mainly isolated thunderstorms elsewhere. Some thunderstorms could be strong in Johnson County. Windy many locations. Rain will turn to snow in the mountains Friday night with 2 to 3 inches of snow expected in Yellowstone Park and 1 to 2 inches expected above 9000 feet in the Teton Range and the Wind River Mountains. Saturday...A chance of thunderstorms the central and north with isolated activity in the south. .SPOTTER INFORMATION STATEMENT... Weather spotters are encouraged to report significant weather conditions according to standard operating procedures. TEAM RIVERTON
Special Weather Statement National Weather Service Riverton WY 239 PM MDT Thu Jun 6 2019 WYZ004>006-062130- North Big Horn Basin-Southeast Big Horn Basin-Southwest Big Horn Basin- 239 PM MDT Thu Jun 6 2019 ...SIGNIFICANT WEATHER ADVISORY FOR NORTH CENTRAL HOT SPRINGS...SOUTH CENTRAL BIG HORN AND NORTHWESTERN WASHAKIE COUNTIES UNTIL 330 PM MDT... At 238 PM MDT, Doppler radar was tracking a strong thunderstorm 13 miles northeast of Legend Rock State Petroglyph Site, which is 24 miles west of Worland, moving northeast at 35 mph. Penny size hail and winds in excess of 40 mph will be possible with this storm. This storm will remain over mainly rural areas of north central Hot Springs, south central Big Horn and northwestern Washakie Counties, including the following locations... Badlands Overlook and Washakie County Fairgrounds. LAT...LON 4385 10851 4394 10863 4430 10813 4404 10775 TIME...MOT...LOC 2038Z 235DEG 29KT 4396 10844 Myers
The Pocatello radar (KSFX), 223 km away, was scanning. The volume nearest the first event began at 20:44 UTC.
1 hail. Local standard time, as filed.
A park ranger at Yellowstone Park reported penny size hail at Madison Junction.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Wyoming in 2019Every state in 2019This day in weather historyWarnings in Wyoming, June 2019
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: 823984.