Another in a series of fast-moving cold fronts and troughs moved through Wyoming and brought another round of high wind to mainly central Wyoming. The highest wind gust recorded was 82 mph at the Red Canyon wind sensor at the southern end of the Wind River Mountains.
Every event with a place to put it; 6 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.
Another in a series of fast-moving cold fronts and troughs moved through Wyoming and brought another round of high wind to mainly central Wyoming. The highest wind gust recorded was 82 mph at the Red Canyon wind sensor at the southern end of the Wind River Mountains. Lower elevation peak speeds included 82 mph in Natrona County and gusts exceeding 60 mph in Fremont and Sweetwater 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 Dec 13, 3:22 AM MST, 1 hour 20 minutes earlier.
Area Forecast Discussion National Weather Service Riverton WY 322 AM MST Mon Dec 13 2021 .SHORT TERM...(Today through Tuesday) Again, the contrast in the conditions, we will split the discussion into West and East of the Divide this morning. West of the Divide...A wave moving up from south and west and is currently bringing a round of snow to the northwest. It is moving and should move out this morning. Moist southwest flow will continue through the day though and additional snow showers are likely. The high resolution models initially did a poor job with this feature though. So, my confidence in pinpointing any snow bands today is low as well. Some areas will likely pick up a few inches of snow but the exact spot is still uncertain. We may issue a special weather statement to cover for this though. A spots may get advisory amounts of snow, but this would either be southwestern Yellowstone, where impacts would be minimal, or in the Tetons, where they want to the snow. This pattern will continue through tomorrow morning. There could be a lull at times, most likely tonight, but again, there are differences in the details. The main event, in the form of a Pacific trough and cold front, will approach on Tuesday and bring some steadier snow. All models have the system moving in, but there are still timing differences. The European is a little faster this morning, moving steadier precipitation in for Tuesday afternoon. The other models are slower, holding it off until Tuesday night. For now, we split the middle and ramped up POPs in the afternoon but not as far east as the European. Highlights will likely be needed for this system though. East of the Divide...Again, here the main concern is wind as it seems someone has hidden the off button for the relentless Wyoming Wind Machine. The wind prone areas near Casper are already seeing wind gusts over 50 mph. The models continue to show 700 millibar winds increasing to 50 to 60 knots. The most widespread strong winds would be on Tuesday though, as the pressure gradient tightens ahead of the approaching Pacific system and we get into the right front quadrant of the jet stream. With the winds already approaching high wind, we upgraded the Green Mountains and Natrona County this morning. There is still a bit more uncertainty in the other zones so we kept those as watches and will punt to the day shift to make the final call on those. Otherwise, expect above normal temperatures to continue across the area through the period. Any potential precipitation from the approaching Pacific system would hold off until at least Tuesday night. There will be more on that in the long term portion of the discussion. .LONG TERM...(Tuesday night through Sunday) Issued at 236 AM MST Mon Dec 13 2021 Southwest flow continues across the area as the next trough and storm system moves into the PACNW and continues eastward to Wyoming. Tuesday night starts with widespread snow across the Western half of Wyoming. There will be some areas of rain mixed with the snow in the Wind River and Bighorn Basins until the temperatures lower enough to change it to all snow. Early Wednesday will see the snow across the entire CWA as the storm system moves quickly eastward. snow amounts will be heaviest across the west, with lighter amounts expected in central Wyoming. A quick moving ridge will push through early Thursday behind the system, followed by another trough moving into the west. This will bring more snow showers along the northwest and west, as the trough moves into the area. Southwest winds Tuesday night will switch to the northwest behind the front on Wednesday. Temperatures will show a significant drop on Wednesday behind the front. Thursday will see snow across western Wyoming, with Friday back to drier weather across the board. The temperatures will stay on the cold side, with only slight warming for next weekend. Models are still varying on the next trough moving across the forecast area for the weekend, so we won't make any major changes at this time. && .AVIATION...12Z Issuance West of the Divide...KBPI/KJAC/KPNA/KRKS Terminals Most terminals will experience VFR conditions through the period. The exception will be KJAC with snow showers continuing around the area through the period. Snow with MVFR to local IFR CIGS and VIS is possible from 18Z-00Z this afternoon for KJAC. The western mountains will see snow at times with some obscuration. KRKS could have gusty winds until about 00Z. East of the Divide....KCOD/KCPR/KLND/KRIW/KWRL Terminals Strong southwest wind will continue at KCPR through the period with gusts to 50kts possible this afternoon. LLWS will be possible at at KLND this morning through 00Z. Gusty winds are possible at KWRL after 01Z. VFR conditions will occur at these terminal sites. Please see the Aviation Weather Center and/or CWSU ZDV and ZLC for the latest information on icing and turbulence forecasts. && .FIRE WEATHER... Snow showers will continue across the west today, with some accumulation likely in the northwestern mountains. Dry conditions will continue East of the Divide for the most part. Strong winds will occur in some locations with high winds likely from the Green and Rattlesnake Ranges through much of Natrona County today. More widespread strong winds are likely on Tuesday ahead of an advancing weather system. Relative humidity will remain above critical levels. Mixing and smoke dispersal will be generally fair to poor in the afternoon. && .RIW WATCHES/WARNINGS/ADVISORIES... High Wind Watch from this evening through Tuesday evening for WYZ015-030. High Wind Warning until 11 PM MST Tuesday for WYZ019-020. High Wind Watch from late tonight through Tuesday evening for WYZ018. High Wind Watch from this evening through Tuesday evening for WYZ009-011. && SHORT TERM...Hattings LONG TERM...Swanson AVIATION...Rowe FIRE WEATHER...Hattings
Hazardous Weather Outlook National Weather Service Riverton WY 319 AM MST Mon Dec 13 2021 WYZ001>020-022>030-141200- 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- 319 AM MST Mon Dec 13 2021 ...High Wind Warnings and Watches have been posted from today through Tuesday evening for portions of Central Wyoming... This Hazardous Weather Outlook is for Western and Central Wyoming. .DAY ONE...Tonight. Snow showers continuing across the western mountains. Strong to high are likely in portions of Natrona, Fremont and Sweetwater Counties. Please see High Wind Warning for details .DAYS TWO THROUGH SEVEN...Monday through Saturday. Tuesday...Strong winds remain possible in parts of Central Wyoming through Tuesday evening. Tuesday night into Wednesday...Snow likely in the west with a chance of snow East of the Divide. Details are still uncertain. Thursday and Friday...Snow looks likely to continue over far western portions. .SPOTTER INFORMATION STATEMENT... Weather spotters are encouraged to report significant weather conditions according to standard operating procedures. McDonald
The national radar mosaic for the moment the first event began.
6 high wind. Local standard time, as filed.
Maximum wind gusts of 74 and 71 mph were reported near Casper along Wyoming Boulevard and Hat Six Road, respectively. A 62 mph wind gust was reported at the Casper-Natrona County International Airport.
A maximum wind gust of 68 mph was reported along Wyoming Highway 220 near Pathfinder Reservoir.
A wind sensor on Wyoming Highway 28 at Red Canyon recorded a peak wind gust of 82 mph.
The peak wind speed in Crowheart was measured at 76 mph.
A maximum wind gust of 69 mph was reported at Hunt Field in Lander.
The ASOS at Southwest Wyoming Regional Airport east of Rock Springs recorded a peak wind gust of 62 mph.
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: 997001, 997000, 997002, 997005, 997003, 997004.