A thunderstorm intensified as it moved off of the Big Horn Mountains and produced locally high winds. A spotter to the west of Buffalo reported a wind gust of 62 mph.
Every event with a place to put it. Tap one for its entry below.
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 thunderstorm intensified as it moved off of the Big Horn Mountains and produced locally high winds. A spotter to the west of Buffalo reported a wind gust of 62 mph.
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 Aug 1, 1:29 PM MST, 3 hours 51 minutes earlier.
Area Forecast Discussion National Weather Service Riverton WY 229 PM MDT Tue Aug 1 2017 .SHORT TERM...(This evening through Friday) Issued at 228 PM MDT Tue Aug 1 2017 A nearly stationary large high pressure ridge aloft will remain over the Western U. S. extending from the Desert Southwest north across the Great Basin into the Pacific Northwest. Northwest flow aloft from Washington and British Columbia will remain over Wyoming with a series of short wave low pressure troughs and associated cold fronts will also continue through Friday. This will keep mild to seasonably cool temperatures over the area. Moisture will be somewhat limited but a frontal convergence boundary will remain over or near the continental divide. This combined with daily heating will support late morning, afternoon and evening showers, with isolated thunderstorms with small hail and strong gusty winds each day, most numerous over the mountains. .LONG TERM...(Friday night through Tuesday) Issued at 228 PM MDT Tue Aug 1 2017 Little change is expected in the main upper level flow pattern Friday night through tuesday with a nearly stationary large high pressure ridge aloft over the Western U. S. extending from the Desert Southwest north across the Great Basin into the Pacific Northwest. Northwest flow aloft from Washington and British Columbia will remain over Wyoming with a series of short wave low pressure troughs and associated cold fronts continuing to move south and east across the area. This will keep mild to seasonably cool temperatures over the area. Moisture will remain somewhat limited but a frontal convergence boundary will remain over or near the continental divide. This combined with daily heating will support late morning, afternoon and evening showers, with isolated thunderstorms with small hail and strong gusty winds each day, most numerous over the mountains. && .AVIATION...(For the 18Z TAFS through 18Z Wednesday afternoon) Issued at 228 PM MDT Tue Aug 1 2017 VFR conditions will prevail through the period. Isolated showers and storms will occur this evening over and near the mountains and adjacent foothills near and east of the Continental Divide. Brief gusty wind to 35 knots will be possible near some storms...to 50 kts north of a KGEY-KBYG-KGCC line. Storms and showers across northern and east central Wyoming will generally decrease across the area after 03z then exit the forecast area altogether between 06z and 12Z. A cold front will also push south into northern WY after 05Z Wed...then south through the rest of the forecast area by around 18z. The front will bring winds around to the north/northeast east of the Divide and over southern Wyoming...to the northwest west of the Divide. Only a few isolated mountain showers or thunderstorms expected in the afternoon. && .FIRE WEATHER... Issued AT 228 PM MDT Tue Aug 1 2017 A nearly stationary large high pressure ridge aloft will remain over the Western U. S. extending from the Desert Southwest north across the Great Basin into the Pacific Northwest. Northwest flow aloft from Washington and British Columbia will remain over Wyoming with a series of short wave low pressure troughs and associated cold fronts will also continue through Friday. This will keep mild to seasonably cool temperatures over the area. Moisture will be somewhat limited but a frontal convergence boundary will remain over or near the continental divide. This combined with daily heating will support late morning, afternoon and evening showers, with isolated thunderstorms with small hail and strong gusty winds each day, most numerous over the mountains. Daytime mixing with sufficient transport winds will produce very good to excellent smoke dispersal from late morning through early afternoon each day. && .RIW WATCHES/WARNINGS/ADVISORIES... NONE. && SHORT TERM...Baker LONG TERM...Baker AVIATION...Braun FIRE WEATHER...Baker
Hazardous Weather Outlook National Weather Service Riverton WY 318 AM MDT Tue Aug 1 2017 WYZ001>020-022>030-021200- 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- 318 AM MDT Tue Aug 1 2017 This Hazardous Weather Outlook is for Western and Central Wyoming. .DAY ONE...Today and Tonight A cold front will bring isolated to widely scattered thunderstorms, mainly in the mountains and east of the divide, some with gusty winds and small hail. .DAYS TWO THROUGH SEVEN...Wednesday through Monday Wednesday...Another cold front pushes south across the area with a chance of showers and thunderstorms, especially along and east of the divide. Thursday through Saturday...widely to scattered afternoon and evening thunderstorms mainly over and near the Wind River and Absaroka Mountains. Sunday...Isolated to widely scattered thunderstorms mainly over and near the mountains. Monday...Scattered afternoon and evening mountains thunderstorms with isolated to widely scattered storms across the lower elevations. .SPOTTER INFORMATION STATEMENT...Spotters are urged to report wind gusts over 45 mph, the size of any hail, any rainfall amounts. Thank you. TEAM RIVERTON
Special Weather Statement National Weather Service Riverton WY 119 PM MDT Tue Aug 1 2017 WYZ001>003-015-016-020000- Yellowstone National Park-Absaroka Mountains-Cody Foothills- Wind River Mountains East-Upper Wind River Basin- Including the cities of Lake, Mammoth, Old Faithful, Cody, Meeteetse, and Dubois 119 PM MDT Tue Aug 1 2017 ...Isolated Thunderstorms Through the Evening... Isolated thunderstorms will develop across the northwest mountains, portions of Yellowstone National Park, and closely adjacent foothills this afternoon through this evening. The main hazards with these storms will be occasional cloud to ground lightning and wind gusts over 30 mph. Some storms may also produce very small hail. This activity will gradually end ...Isolated Thunderstorms Through the Evening... Isolated thunderstorms will develop across the northern mountains and adjacent foothills this afternoon through this evening. The main hazards with these storms will be occasional cloud to ground lightning and a few wind gusts 30 to 50 mph. Some storms may also produce very small hail. This activity will gradually through the early evening period. through the early evening period. WYZ008>011-020000- Bighorn Mountains West-Bighorn Mountains Southeast- Northeast Johnson County-Southeast Johnson County- Including the cities of Buffalo and Kaycee 119 PM MDT Tue Aug 1 2017 ...Isolated Thunderstorms Through the Evening... Isolated thunderstorms will develop across the northern mountains and adjacent foothills this afternoon through this evening. The main hazards with these storms will be occasional cloud to ground lightning and a few wind gusts 30 to 50 mph. Some storms may also produce very small hail. This activity will gradually end through the early evening period. WYZ020-022-020000- Natrona County Lower Elevations-Casper Mountain- Including the city of Casper 119 PM MDT Tue Aug 1 2017 ...Isolated Thunderstorms Through the Evening... Isolated thunderstorms will develop across the central mountains and adjacent foothills and lower elevations of Natrona County this afternoon through this evening. The main hazards with these storms will be occasional cloud to ground lightning and a few wind gusts over 30 mph. Some storms may also produce very small hail. This activity will gradually end through the early evening period.
Special Weather Statement National Weather Service Riverton WY 220 PM MDT Tue Aug 1 2017 WYZ001>003-007-015-016-020000- Yellowstone National Park-Absaroka Mountains-Cody Foothills- Owl Creek and Bridger Mountains-Wind River Mountains East- Upper Wind River Basin- Including the cities of Lake, Mammoth, Old Faithful, Cody, Meeteetse, and Dubois 220 PM MDT Tue Aug 1 2017 ...Isolated Thunderstorms Through the Evening... Isolated thunderstorms will develop across the northwest mountains, portions of Yellowstone National Park, Owl Creek Mountains, and closely adjacent foothills of the area this afternoon through this evening. The main hazards with these storms will be occasional cloud to ground lightning and wind gusts over 30 mph. Some storms may also produce very small hail. This activity will gradually through the early evening period. WYZ008>011-020000- Bighorn Mountains West-Bighorn Mountains Southeast- Northeast Johnson County-Southeast Johnson County- Including the cities of Buffalo and Kaycee 220 PM MDT Tue Aug 1 2017 ...Isolated Thunderstorms Through the Evening... Isolated thunderstorms will develop across the northern mountains and adjacent foothills this afternoon through this evening. The main hazards with these storms will be occasional cloud to ground lightning and a few wind gusts 30 to 45 mph. Some storms may also produce very small hail. This activity will gradually end through the early evening period. WYZ020-022-020000- Natrona County Lower Elevations-Casper Mountain- Including the city of Casper 220 PM MDT Tue Aug 1 2017 ...Isolated Thunderstorms Through the Evening... Isolated thunderstorms will develop across the central mountains and adjacent foothills and lower elevations of Natrona County this afternoon through this evening. The main hazards with these storms will be occasional cloud to ground lightning and a few wind gusts over 30 mph. Some storms may also produce very small hail. This activity will gradually end through the early evening period.
Special Weather Statement National Weather Service Riverton WY 343 PM MDT Tue Aug 1 2017 WYZ001>007-016-017-020000- Yellowstone National Park-Absaroka Mountains-Cody Foothills- North Big Horn Basin-Southwest Big Horn Basin- Southeast Big Horn Basin-Owl Creek and Bridger Mountains- Upper Wind River Basin-Wind River Basin- Including the cities of Lake, Mammoth, Old Faithful, Cody, Meeteetse, Thermopolis, Worland, Dubois, Riverton, and Shoshoni 343 PM MDT Tue Aug 1 2017 ...Isolated Thunderstorms Through the Evening... Isolated thunderstorms will develop across the northwest mountains, portions of east Yellowstone National Park, Owl Creek Mountains, and closely adjacent foothills of the Big Horn Basin area this afternoon through this evening. The main hazards with these storms will be occasional cloud to ground lightning and wind gusts over 30 mph. Some storms may also produce very small hail. This activity will gradually through the early evening period. WYZ008>011-020000- Bighorn Mountains West-Bighorn Mountains Southeast- Northeast Johnson County-Southeast Johnson County- Including the cities of Buffalo and Kaycee 343 PM MDT Tue Aug 1 2017 ...Isolated Thunderstorms Through the Evening... Isolated thunderstorms will develop across the northern mountains and adjacent foothills this afternoon through this evening. The main hazards with these storms will be occasional cloud to ground lightning and a few wind gusts 30 to 45 mph. Some storms may also produce very small hail. This activity will gradually end through the early evening period. WYZ020-022-020000- Natrona County Lower Elevations-Casper Mountain- Including the city of Casper 343 PM MDT Tue Aug 1 2017 ...Isolated Thunderstorms Through the Evening... Isolated thunderstorms will develop across the central mountains and adjacent foothills and lower elevations of Natrona County this afternoon through this evening. The main hazards with these storms will be occasional cloud to ground lightning and a few wind gusts over 30 mph. Some storms may also produce very small hail. This activity will gradually end through the early evening period.
Special Weather Statement National Weather Service Riverton WY 459 PM MDT TUE AUG 1 2017 WYZ017-012315- Wind River Basin- 459 PM MDT TUE AUG 1 2017 ...SPECIAL WEATHER STATEMENT... At 456 PM MDT, Doppler radar was tracking a strong thunderstorm near Riverton, moving southeast at 25 mph. Small hail and heavy rain will will occur with this storm in some areas. This storm will move across the Riverton area through 530 PM. Seek safe shelter indoors. LAT...LON 4298 10855 4315 10846 4308 10805 4283 10819 TIME...MOT...LOC 2256Z 291DEG 24KT 4304 10841 AR
Special Weather Statement National Weather Service Riverton WY 528 PM MDT TUE AUG 1 2017 WYZ017-020015- Wind River Basin- 528 PM MDT TUE AUG 1 2017 ...SPECIAL WEATHER STATEMENT... At 526 PM MDT, Doppler radar was tracking a thunderstorm 7 miles east of Riverton, moving east at 20 mph. Half inch hail and winds in excess of 30 mph will be possible with this storm along with occasional cloud to ground lightning and locally heavy rainfall. This storm will remain over mainly rural areas of eastern Fremont County including Gas Hills Road. LAT...LON 4298 10832 4304 10833 4304 10801 4286 10800 TIME...MOT...LOC 2326Z 290DEG 16KT 4300 10825 Lipson
The Riverton/Lander radar (KRIW), 198 km away, was scanning. The volume nearest the first event began at 00:21 UTC.
1 thunderstorm wind. Local standard time, as filed.
A trained spotter measured a wind gust of 62 mph around 6 miles west-northwest of Buffalo.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Wyoming in 2017Every state in 2017This day in weather historyWarnings in Wyoming, August 2017
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: 705679.