High wind occurred in wind-prone areas around the community of Clark ahead of an approaching cold front. The maximum reported wind gust was 76 mph.
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The episode as NWS RIW wrote it up.
High wind occurred in wind-prone areas around the community of Clark ahead of an approaching cold front. The maximum reported wind gust was 76 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 Dec 20, 11:32 AM MST, 3 hours 28 minutes earlier.
Area Forecast Discussion National Weather Service Riverton WY 1132 AM MST Mon Dec 20 2021 .SHORT TERM...Today through Tuesday Low clouds with freezing fog and/or drizzle will remain possible over portions of Johnson County through sunrise this morning. The low clouds in the Bighorn Basin are expected to begin to scatter out by sunrise. Snow showers over far northwestern portions will gradually end later this morning. Accumulations of 1 to 2 inches are expected during this time. Locally higher amounts of 3 to 5 inches will be possible near the northeast entrance to Yellowstone. A flat ridge will remain in place over the Cowboy State today. However, a jet streak will make its way over far northern portions by this evening. The right exit region of this streak will allow for downward motion over this area this afternoon and evening, before passing to the east. In addition, the tight temperatures gradient along the Cody Foothills will remain in place as well. These features, in addition to 700mb winds of 50 to 60 kt, will cause high winds with gusts of 60 to 70 mph to occur near Clark and Cody. Will continue the High Wind Warning for this area. Similar winds will occur along the east slopes of the Absaroka, Bighorn and Wind River Mountains. Southwest winds, with gusts of 45 to 55 mph will also continue across the Wind Corridor today. Gusts of 60 mph will remain possible over the south side of Casper. Winds will gradually decrease tonight, as the jet streak exits over the Northern Plains. The flow aloft will turn more northwesterly Tuesday. Gap flow will remain possible near Clark, along with gusty winds over the Wind Corridor. The temperature gradient and 700mb winds of 50 kt will continue along the Cody Foothills. Otherwise, conditions are expected to be dry and temperatures slightly above normal. This will probably be the nicest day of the week. .LONG TERM...Tuesday night through Sunday Not a whole lot going on at the beginning of the period, as mostly dry conditions and "warmer" temperatures are continued to be ushered into the area. The main concern is the potent southwesterly flow that is present. The last few weeks we've seen potent southwesterly flow bring increased surface winds across portions of Natrona and Fremont counties and that trend is expected to continue for Wednesday. High wind highlights may be needed for areas through the Wind Corridor for Wednesday afternoon. Attention quickly turns towards the next impactful system, as models are still continuing to hammer out solutions. In recent runs, there's been a few more tweaks as the potential cut-off has been eliminated and a digging trough just digs over California and will be the main force for this event. As the center of the jet energy moves overhead for Wednesday, the western mountains will see increased chances for snow Wednesday afternoon and continuing through into Thursday. As for the eastern areas, high wind highlights may be needed again for Thursday afternoon. As the gradient tightens and pre-frontal winds exist, high wind will be possible Thursday afternoon. The trough will continue to swing southeastward Thursday and PoPs will spread with it. Areas east of the Divide could see rain transitioning to snow as southwesterly flow will advect above freezing temperatures ahead of the front Thursday into Friday. The system quickly exits Friday afternoon, but with initial snowfall amounts, there could be a white Christmas for areas in the western zones. Presently, initial snowfall amounts look to be on the higher end of advisory amounts but as models continue to decipher this system, there could be some swings in overall amounts. Models are quickly moving another system into the region for late Christmas night into Sunday, which looks to be bringing another wave of accumulating snow to the region. This is still a week out; therefore, not going to dive into the details that don't necessarily exist yet but will mention that models are suggesting an active period to end the year. && .AVIATION...(For the 18Z TAFS through 18Z Tuesday afternoon) Issued at 1038 AM MST Mon Dec 20 2021 Mainly VFR conditions are expected to prevail as ceilings lift or dissipate early this afternoon. Main concern will be the strong west to southwest wind at KCOD and to a lesser degree KCPR through tonight. Wind will decrease after around 12z Tuesday morning but will remain gusty through the period. A weak system could bring isolated showers across the north around 10z but not confident on any terminal impacts at this time. Please see the Aviation Weather Center and/or CWSU ZDV and ZLC for the latest information on icing and turbulence forecasts. && .FIRE WEATHER... Strong winds, with gusts over 60 mph, will occur over portions of zone 276 later this afternoon and tonight. Similar winds will occur over zones 286/288 and the eastern slopes of the Bighorns. Southwest winds, with gusts of 45 to 55 mph will continue over zones 280/289. These winds are expected to return and spread to portions of zones 283/288 Wednesday. Temperatures will be slightly above normal east of the Divide Tuesday. Western zones could have several rounds of snow starting Wednesday night into early next week. && .RIW WATCHES/WARNINGS/ADVISORIES... High Wind Warning until 8 AM MST Tuesday for WYZ003. && SHORT TERM...LaVoie LONG TERM...Vorst AVIATION...Myers FIRE WEATHER...LaVoie
Hazardous Weather Outlook National Weather Service Riverton WY 321 AM MST Mon Dec 20 2021 WYZ001>020-022>030-211030- 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- 321 AM MST Mon Dec 20 2021 ...High Wind Warning for the Cody Foothills this afternoon through early Tuesday morning... This Hazardous Weather Outlook is for Western and Central Wyoming. .DAY ONE...Today and Tonight. West winds, with gusts over 60 mph, will develop late this afternoon near Cody and Clark. These winds are expected through the overnight hours. Southwest winds with gusts between 40 and 50 mph will continue in Natrona County, especially in the Casper area. .DAYS TWO THROUGH SEVEN...Tuesday through Sunday. Wednesday Night...Snow returns to the western mountains. Thursday into Christmas Eve...Snow continues west of the Divide before spreading eastward through the day Thursday. Christmas Day and Sunday...Snow likely over far western portions, with chances spreading across the south Sunday. .SPOTTER INFORMATION STATEMENT... Weather spotters are encouraged to report significant weather conditions according to standard operating procedures.
The national radar mosaic for the moment the first event began.
1 high wind. Local standard time, as filed.
A maximum wind gust of 76 mph occurred to the west of Clark near the foothills of the Absaroka Range.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Wyoming in 2021Every state in 2021This day in weather historyWarnings in Wyoming, December 2021
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: 997007.