Thunderstorms moved through northern Wyoming as a shortwave trough crossed the area. With large dew point depressions, very strong wind gusts occurred with the high-cloud-base showers and storms.
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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.
Thunderstorms moved through northern Wyoming as a shortwave trough crossed the area. With large dew point depressions, very strong wind gusts occurred with the high-cloud-base showers and storms. Wind gusts of 60 to 65 mph occurred across portions of Big Horn and Johnson Counties.
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 Jul 15, 12:45 PM MST, 2 hours 30 minutes earlier.
Area Forecast Discussion National Weather Service Riverton WY 145 PM MDT Fri Jul 15 2022 .SHORT TERM...(This afternoon through Saturday night) Issued at 145 PM MDT Fri Jul 15 2022 A shortwave trough is moving from west-central Utah to northern Colorado and southeast WY today, continuing the moist unstable SW flow over the forecast area. As expected, light showers pushed into southwest and south-central WY this morning. Current forecast of scattered to widespread showers and thunderstorms is still on track for the afternoon and early evening, though a bit concerned over reduction of surface heating due to extensive cloud cover. Thunderstorm activity is most likely to start over southwest WY and move NE. The higher terrain elsewhere in the forecast area will see thunderstorms develop by 3pm, then move east during the early evening hours. Given the high precipitable water values and the monsoon-like pattern, WPC has extended the excessive rain outlook from southern WY into Johnson and Natrona Counties, and then over to YNP area during the early evening. Certainly is a good pattern for some localized heavy rain from stronger storms. At the same time, another shortwave trough is moving from central ID into western/central MT today. This system is expected to generate moderate convection from central into SW MT then move into northwest and northern WY during the evening. In addition of brief heavy rain, storms across the northern sections this evening could produce strong outflow over 40 mph, due to the jet streak and more favorable wind shear. Post-system flow late this evening and overnight should turn NW with lingering showers over the Bighorn Basin and mountain areas. High pressure then builds Saturday morning as skies clear and temperatures rise again. Most of the area will be dry and warm, though high resolution models are fairly confident that isolated convection will break out over west-central WY ;ate in the afternoon. Could also see a couple of showers and storms along the MT/WY border near YNP and the Absarokas. Afternoon temps are likely to rise 4-6 degrees over Friday, but stay about the same across northern WY. The upper- level ridge axis then moves from ID eastward over WY Sunday morning. Generally light to breezy winds are expected, except for gusty outflow out of any thunderstorms. .LONG TERM...(Sunday through Friday) Issued at 145 PM MDT Fri Jul 15 2022 The Four Corners high amplifies a bit Sunday in response to a closed- low approaching the Pacific Northwest coast. 700mb temperatures warm slightly over those seen on Saturday enabling daytime maximums to approach near-record readings for the date. Highs will be in the 90s across the lower elevations with 100-104F still on-track for the Bighorn River Valley in Big Horn and Washakie counties. There should be enough mid-level moisture to generate isolated showers and storms west of the Continental Divide late in the day. The best chance may come in the early evening across the northwest mountains after peak heating aids in breaking a mid-level cap. The main hazard would be gusty outflow wind. The aforementioned closed-low tracks east along the US/Canada border Monday and Monday night flattening the upper ridge. The track of this system tightens the pressure gradient leading to breezy to windy conditions Monday afternoon. Deterministic solutions continue to indicate 25-35kt 700mb winds, while ensemble solutions depict surface mean gusts 30 to 35 mph. Confidence is rising in support of a windy Monday afternoon. The combination of the gusty wind and above normal temperatures leads to elevated fire weather conditions Monday afternoon and evening. Convection Monday looks to be confined to the higher terrain and the far south. The shortwave continues eastward overnight and pushes a weak cold front south across northern and central Wyoming. While still above normal, Tuesday highs will be cooler east of the Continental Divide following frontal passage. Daytime highs in this region will be 5-8F cooler, while temperatures west of the Divide remain largely unchanged and still above normal. The pressure gradient relaxes Tuesday, but gusty northwest wind remains, especially across the southwest basins. The Four Corners high retrogrades and elongates across the Desert Southwest US Tuesday limiting any northward moisture surges and shortwaves. Wednesday and Thursday see a continuation of the above normal temperatures and mainly isolated convection across the western mountains. The relatively flat ridge leads to westerly flow aloft and favors breezy conditions along and west of the Divide through the latter half of the week. && .AVIATION...(For the 18Z TAFS through 18Z Saturday) Issued at 1124 AM MDT Fri Jul 15 2022 VFR conditions prevail through 18Z/Saturday. Moist southwest flow aloft has kept extensive mid/high cloud cover across central and southwest Wyoming this morning. This has limited surface heating and destabilization, so convective development has been limited to a line of showers moving into central Wyoming. A shortwave moving in from the southwest and additional heating should allow for more widespread convection between 21Z/Fri and 01Z/Sat. The best chance for brief MVFR would be with heavier rain, and KRKS presents the best chance for that. Showers and storms tracks northeast through the forecast area into early Friday evening before waning. Showers linger until around 06Z/Sat before the shortwave departs to the east and drier air works into the state from the west. Expect clearing skies and light wind by 12Z/Sat, conditions which prevail through 18Z/Sat. 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 145 PM MDT Fri Jul 15 2022 For the third day in a row, a monsoon-like pattern continues to impact western and central WY with above normal temps, high moisture content, only breezy winds, and a good chance of showers and thunderstorms. This afternoon will see areas of showers become more convective with scattered thunderstorms. Due to a weak disturbance, some storms could produce brief heavy rain and strong outflow winds over 40 mph, especially across southwest into southern WY. Another disturbance across Montana today will bring some strong storms to YNP into the Bighorn Basin and Johnson County later in the afternoon and early evening. Both systems move eastward by Saturday morning to bring clearing skies and warming temperatures with weak northwest flow. Isolate showers and thunderstorms are possible over west- central WY Sat afternoon. Warmer and drier conditions continue Sunday with high pressure, though late day storms are possible over western WY Sun afternoon. && .RIW WATCHES/WARNINGS/ADVISORIES...NONE. && SHORT TERM...McDonald LONG TERM...CNJ AVIATION...CNJ FIRE WEATHER...McDonald
Hazardous Weather Outlook National Weather Service Riverton WY 747 AM MDT Fri Jul 15 2022 WYZ001>020-022>030-161300- 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- 747 AM MDT Fri Jul 15 2022 This Hazardous Weather Outlook is for Western and Central Wyoming. .DAY ONE...Today and Tonight. Isolated to locally scattered afternoon and evening thunderstorms. Heavy rain possible across Sweetwater County. .DAYS TWO THROUGH SEVEN...Saturday through Thursday. Saturday and Sunday...Hot with near-record temperatures. Isolated afternoon thunderstorms. Monday...Near critical to critical fire weather conditions possible. .SPOTTER INFORMATION STATEMENT... Spotters are encouraged to report any significant weather.
Special Weather Statement
National Weather Service Riverton WY
318 PM MDT Fri Jul 15 2022
WYZ002-015-016-152215-
Upper Wind River Basin-Wind River Mountains East-Absaroka Mountains-
318 PM MDT Fri Jul 15 2022
...A strong thunderstorm will impact portions of northwestern Fremont
County through 415 PM MDT...
At 317 PM MDT, Doppler radar was tracking a strong thunderstorm 9
miles northwest of Dubois, moving east at 5 mph.
HAZARD...Winds in excess of 30 mph and pea size hail along with
locally heavy rain.
SOURCE...Radar indicated.
IMPACT...Gusty winds could knock down tree limbs and blow around
unsecured objects. Minor damage to outdoor objects is
possible. Minor flooding in local creeks may occur.
Locations impacted include...
Areas northwest of Dubois.
PRECAUTIONARY/PREPAREDNESS ACTIONS...
If outdoors, consider seeking shelter inside a building.
Locally heavy rainfall up to one inch over 30 minutes is also
occurring with this storm and may lead to localized flooding. Do not
drive your vehicle through flooded roadways.
Persons in campgrounds should consider seeking sturdy shelter until
this storm passes.
&&
LAT...LON 4353 10990 4375 10987 4376 10963 4352 10966
TIME...MOT...LOC 2117Z 254DEG 5KT 4363 10979
MAX HAIL SIZE...0.25 IN
MAX WIND GUST...30 MPH
McDonaldThe Billings radar (KBLX), 105 km away, was scanning. The volume nearest the first event began at 22:15 UTC.
4 thunderstorm wind. Local standard time, as filed.
A maximum wind gust of 64 mph was recorded at the Cowley Airport.
A maximum wind gust of 63 mph was reported at the South Big Horn County Airport near Greybull.
The Willow Creek RAWS weather sensor recorded a maximum wind gust of 64 mph.
A maximum wind gust of 61 mph was reported at the Johnson County Airport near Buffalo.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Wyoming in 2022Every state in 2022This day in weather historyWarnings in Wyoming, July 2022
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: 1045348, 1045350, 1045349, 1045351.