A slow moving low pressure system brought a deep fetch of moisture into portions of northern and central Wyoming. In the favored easterly upslope areas, heavy snow fell in the mountains and heavy rain fell in the lower elevations.
Every event with a place to put it; 5 filed by county or forecast zone are drawn at its center, in a lighter ring. 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 slow moving low pressure system brought a deep fetch of moisture into portions of northern and central Wyoming. In the favored easterly upslope areas, heavy snow fell in the mountains and heavy rain fell in the lower elevations. The heaviest snow and rain fell in Park County. Up to 3 feet of new snow fell in the Absaroka Range with 37 inches at the Marquette SNOTEL site.
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 May 29, 1:41 PM MST, 1 hour 19 minutes earlier.
Area Forecast Discussion National Weather Service Riverton WY 241 PM MDT Sun May 29 2022 .SHORT TERM...(This Afternoon through Monday Night) Issued at 241 PM MDT Sun May 29 2022 Morning sunshine allowed for enough solar heating to aid convective development over the mountains of central Wyoming shortly before 12 noon Sunday. Multiple circulations, one over northern Utah and another in eastern Idaho, have spawned multiple bands of showers and cloud cover to pinwheel across the forecast area this afternoon. The nose of a weak jet streak along with diffluent flow aloft are further assisting in generating scattered showers and storms over much of the region. Mid-level winds are not favorable for gusty outflow wind, so the primary hazard will be small hail. Convection will at least decrease in intensity with the loss of daytime heating this evening. As Sunday evening wears on, a mid-level low begins to organize over central/northern Wyoming. Wrap-around moisture and dynamic lift associated with this circulation favors precipitation across the north half of the state later tonight through Monday morning. Colder air moves into the western valleys and basins around 06Z/Monday with 700mb temperatures pointing to a changeover to all snow during the early morning hours Monday. Valley accumulations will generally be an inch or less, mainly on grassy surfaces. The western mountains could see about 4 to 8 inches of snow by sunrise Monday. To the east of the Continental Divide, snow levels keep accumulating snow above the 7500-8000 foot elevation. However, northeasterly 700mb winds and enhanced dynamics will favor heavier snowfall as the orographics drive snowfall on the north and east facing slopes of the Bighorn and Absaroka ranges, especially after midnight Monday. Lower elevations of the north are looking at overnight rainfall of one-third to two-thirds of an inch on average. While snow will begin to fall in the Wind River Range, favorable orographics hold-off until after 12Z/Monday. Monday morning finds the mid- and upper-level lows beginning to redevelop and deepen to the east of the forecast area. This allows for stronger 700mb winds to aid orographics and drives the upslope south into central Wyoming. Valley rain and higher elevation snow increases through the day across central Wyoming, while western areas see a noticeable decrease in intensity and even coverage by late afternoon. Snow accumulation across the western valleys will be negligible by 9 AM Monday. Gusty northerly surface wind of 20 to 30 mph with gusts around 40 mph will combine with the rain and temperatures 20F-25F below normal to create a blustery day across northern Wyoming. Wind speeds in central Wyoming will be a tad lower, but brisk nonetheless. Upslope precipitation should intensify in the central basins between 1 PM and 5 PM Monday leading to widespread steady rain. The rain lingers through the overnight hours across the central basins, although intensity will decrease after midnight Tuesday. Drier air does begin to work into the far north late in the night allowing for precipitation to begin to slow down prior to sunrise Tuesday. A secondary circulation moves into the base of the broad trough over the Intermountain West Monday night. This leads to an area of deformation developing over southwest Wyoming, increasing the chance of precipitation after midnight Tuesday. However, the best lift remains across the upslope favored locations from Lander to Casper through the overnight hours. The gusty northerly wind gradually diminishes as the pressure gradient relaxes in response to the mid- and upper-level circulations pulling away from the state. .LONG TERM...(Tuesday through Sunday) Issued at 241 PM MDT Sun May 29 2022 The upper level low will be over northern Nevada, with rain and mountain snow continuing across the area on Tuesday. It will still be unseasonably cool as well. There will be isolated afternoon thunderstorms possible. This low slowly moves eastward and opens into a minor trough by Wednesday. The GFS is still quicker on moving the trough out of the area, with the European a bit slower and keeping the QPF higher across the state through the day. Wednesday will see slightly warmer temperatures as skies clear a bit with the exit of the trough. They will still be below normal. Thursday and Friday finds a ridge across the area for a drier pattern over much of the south. However, it will be a dirty ridge Friday into Saturday with shortwaves sliding across the north and kicking off some showers and possible thunderstorms. The good news is that the temperatures will see an increase to more normal values. There are some early indications for low humidity and warmer temperatures on Friday, so there could be areas of elevated fire weather conditions. Winds will be stronger on Friday and Saturday afternoons as well, which could enhance conditions. That is something we will monitor. Models keep the ridge moving eastward Saturday into Sunday, bringing better chances of widespread precipitation and switching the flow back to the southwest. Temperatures will stay on the warmer side, though not too warm. && .AVIATION...(For the 18Z TAFS through 18Z Monday) Issued at 1154 AM MDT Sun May 29 2022 West of the Divide...KBPI/KJAC/KPNA/KRKS Terminals Closed low to our west will slowly track overhead tonight. Convection to become more widespread this afternoon as shortwave energy pinwheels across the region ahead of this low. Occasional MVFR anticipated through 02Z/Monday with the stronger showers/storms. KJAC to see MVFR continue overnight with rain changing to snow around 06Z/Monday. Conditions improve at other terminals until MVFR ceilings develop at KBPI and KPNA between 08Z-12Z/Monday. Mountain tops frequently obscured. East of the Divide...KCOD/KCPR/KLND/KRIW/KWRL Terminals Convection firing off the central mountains late this morning as shortwave energy pinwheels across the region ahead of an approaching upper low. Convection prevails into the evening with occasional MVFR with the stronger showers/storms. A mid-level low takes shape over northern Wyoming tonight with wrap-around moisture leading to IFR/MVFR conditions at KCOD and KWRL by early Monday. KRIW and KLND may not see better upslope and deteriorating conditions until late Monday morning. KCPR forecast is a challenge with the possibility of lowering ceilings a few hours earlier than KRIW/KLND. Mountain tops frequently obscured through 03Z/Monday, then mountain tops obscured. 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 241 PM MDT Sun May 29 2022 Conditions turn wet Sunday night and remain that way through at least Monday evening. Initially, the best chance for rain and mountain snow will be across the northern-third of the state. By midday Monday, steady rain and mountain snow (particularly above 8000 ft MSL) will have spread to most areas with the exception of the southwest portion of the state. Rain lingers across central Wyoming and eventually spreads back into southwest Wyoming Tuesday. Temperatures both days will be around 20-25F below seasonal normals, particularly east of the Continental Divide. Gusty north-northwest wind develops Monday across Johnson County and much of the Bighorn Basin. Surface wind speeds of 20 to 30 mph with gusts around 40 mph occur during the day. Smoke dispersal will be good to very good Monday across Sweetwater County and neighboring areas. Despite low mixing heights, the gusty northerly wind aids smoke dispersal across the northern basins Monday. Good smoke dispersal will be the general rule for Tuesday afternoon. Wednesday begins a steady warming and drying trend for the rest of the week as a ridge of high pressure nudges into the region from the west. && .RIW WATCHES/WARNINGS/ADVISORIES... Winter Storm Warning from 6 PM this evening to noon MDT Tuesday for WYZ002-008-009. Winter Storm Warning from 9 PM this evening to noon MDT Tuesday for WYZ015. Winter Weather Advisory from 6 PM this evening to 3 PM MDT Monday for WYZ001-012. && SHORT TERM...CNJ LONG TERM...Swanson AVIATION...CNJ FIRE WEATHER...CNJ
Hazardous Weather Outlook National Weather Service Riverton WY 842 AM MDT Sun May 29 2022 WYZ001>020-022>030-301300- 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- 842 AM MDT Sun May 29 2022 ...Winter Storm Warnings for Portions of the Northern and Central Mountains Tonight through Tuesday Morning... ...Winter Weather Advisories for Yellowstone National Park and the Teton and Gros Ventre Ranges Tonight into Monday Afternoon... This Hazardous Weather Outlook is for Western and Central Wyoming. .DAY ONE...Today and Tonight. Rain showers and isolated thunderstorms spread northeast across the region through the day. A few thunderstorms along and east of a line from Rock Springs to Casper could produce gusty outflow wind and small hail. The onset of nightfall and the arrival of colder air will lead to heavy mountain snow tonight, especially after midnight. .DAYS TWO THROUGH SEVEN...Monday through Saturday. Monday and Tuesday...A storm system impacts the area with valley rain, mountain snow, and a few thunderstorms. Heavy mountain snow continues into Tuesday morning, particularly over the northern mountains and east slope of the Wind River Range. .SPOTTER INFORMATION STATEMENT... Weather spotters are encouraged to report significant weather conditions.
Special Weather Statement National Weather Service Riverton WY 258 PM MDT Sun May 29 2022 WYZ013-023-301300- Jackson Hole-Star Valley- Including the cities of Jackson, Afton, Alpine, Star Valley Ranch, and Thayne 258 PM MDT Sun May 29 2022 ...Light Snow Sunday Night... This is a special weather statement from the National Weather Service office in Riverton. * WHAT...Light snow with accumulations generally less than an inch on grassy surfaces. * WHERE...Jackson and Star Valleys. * WHEN...Sunday night, mainly after midnight, into early Monday morning. WYZ024-301300- Salt River and Wyoming Ranges- 258 PM MDT Sun May 29 2022 ...Accumulating Snow through Sunday Night... This is a special weather statement from the National Weather Service office in Riverton. * WHAT...Snow with accumulations of 3 to 5 inches, mainly above 8000 feet. * WHERE...Salt River and Wyoming Mountain Ranges. * WHEN...Through early Monday morning. * ADDITIONAL DETAILS...Salt River Pass may be slick for the Monday morning commute. WYZ025-301300- Upper Green River Basin Foothills- Including the city of Pinedale 258 PM MDT Sun May 29 2022 ...Light Snow Sunday night... This is a special weather statement from the National Weather Service office in Riverton. * WHAT...Light snow with accumulations generally less than an inch on grassy surfaces. Rim Divide could see 1 to 2 inches of snowfall. * WHERE...Upper Green River Basin. * WHEN...Sunday night, mainly after midnight, into early Monday morning.
The national radar mosaic for the moment the first event began.
5 winter storm. Local standard time, as filed.
Favorable upslope easterly flow brought heavy snow to the southeastern Bighorn Range, especially above 8000 feet. The highest amounts reported was 33 inches at the Cloud Peak Reservoir SNOTEL site.
Heavy snow fell at the Parker Peak SNOTEL site where 24 inches of new snow was measured.
Heavy snow fell in northern portions of the Bighorn Mountains. The highest amount recorded was 25 inches the Bone Springs SNOTEL site. Amounts dropped further southward and in the lower elevations.
Favorable easterly upslope flow brought very heavy snow to the Absarokas. There were numerous reports of over 18 inches of snow with a maximum of 37 inches at the Marquette SNOTEL site.
Heavy snow fell in portions of the Wind River Range, mainly above 8000 feet. The highest amount was at the Hobbs Park SNOTEL site where 24 inches of new snow fell. Measured amounts elsewhere were 14 inches or less.
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, May 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: 1029356, 1029360, 1029355, 1029357, 1029359.