Strong winds developed near Arlington and Elk Mountain late in the evening on the 27th, briefly spilling into WY-Z109 with 60+ MPH gusts reported as far west as Rawlins for less than one hour. Gusts near Arlington persisted into the night and eventually into the mid afternoon hours on the 28th.
Every event with a place to put it; 2 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 CYS wrote it up.
Strong winds developed near Arlington and Elk Mountain late in the evening on the 27th, briefly spilling into WY-Z109 with 60+ MPH gusts reported as far west as Rawlins for less than one hour. Gusts near Arlington persisted into the night and eventually into the mid afternoon hours on the 28th. Frequent gusts 65-75 were observed with a peak gust to 78 MPH at County Road 402 along I-80.
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 Cheyenne, WY wrote its last area forecast discussion before the first event at Dec 27, 4:40 PM MST, 5 hours 42 minutes earlier.
Area Forecast Discussion National Weather Service Cheyenne WY 440 PM MST Mon Dec 27 2021 .SHORT TERM...(This evening through Wednesday night) Issued at 120 PM MST Mon Dec 27 2021 A nice break today as we have been plagued by various weather elements. Forecast challenges deal with snow and high wind chances in the short term. Currently...CWA remains under southwest flow this afternoon with a stalled surface front laying across northern Wyoming. 1000mb surface low over northwestern Wyoming with a cold front extending southwest into northern Utah and Nevada. Sierra MAdres and SNowy Ranges still getting light snow reports with 3 hourly SWE reports of up to .2 to .3 inches. Will continue current Winter Storms for these two zones through Tuesday morning. Still a small threat for snow squalls today as NAM snow squall parameters around 4.5 units in Carbon County this afternoon. Nothing like yesterday...but there is around 150-200 J/KG CAPE across Carbon County. Will continue to monitor radar trends through the afternoon. Gradients ease this evening through Tuesday for less wind. Could see some pretty cold temperatures tonight with the decreasing winds. Single digit lows definitely a possibility...especially where there is snow on the ground. Possibly some breezy areas Tuesday...especially in the wind prone areas as GFS 700mb winds up near 45kts. Gradients low however...so am not anticipating any wind headlines at this time. Winds on the increase Wednesday as Clipper system moves into Montana. Craig to Casper 850/700mb height gradients on the increase after 00Z Wednesday night as 700mb winds increase to 50-55kts. Likely looking at High Wind headlines after 00Z into Thursday. .LONG TERM...(Thursday through Monday) Issued at 120 PM MST Mon Dec 27 2021 Thursday...For the penultimate day of the year, should see a slight modification in maximum temperatures with some downslope warming. Strong west flow at low and mid levels will continue to produce a windy day with our wind prone locations possibly seeing high wind criteria. Friday...For the final day of the year, the next shortwave trough aloft carves out over western Wyoming and Utah with colder air pushing southward across Wyoming for the first few days of January. One more seasonable day before the colder air filters in for the start of the holiday weekend. Moist flow aloft will help produce widespread orographic snows again for the Snowy and Sierra Madre Ranges, with scattered snow showers elsewhere across southeast Wyoming. New Years Day...High amplitude shortwave trough aloft passes across Wyoming, producing scattered snow showers early in the day, followed by drying in its wake. Turning much colder in the wake of the associated cold front. Sunday...The progressive pattern aloft continues with the flow aloft quickly backing to strong westerly, inducing a developing surface lee trough, and a decent warming trend. Strong low and mid level gradients suggest another windy day, with perhaps strong winds for our typically wind prone locations across southeast Wyoming. Monday...The westerly flow aloft continues with 700 mb temperatures rising to near -3 Celsius, yielding maximum temperatures in the mid 20s to mid 30s west, and 40s east. The low and mid levels look too dry for any precipitation. && .AVIATION...(For the 00Z TAFS through Tuesday afternoon) Issued at 440 PM MST Mon Dec 27 2021 Another Pacific upper level trough will push across Wyoming and western Nebraska tonight, resulting in colder temperatures and another quick shot of snow late this evening. Not much, if any, snow is expected to fall across western Nebraska due to downslope west to northwest winds. It will remain windy with gusts of 35 to 40 knots near KRWL, with winds increasing out of the northwest closer to sunrise Tuesday further east. HAZARDS/WEATHER TRENDS: VFR conditions should prevail for most terminals over the next 18 to 24 hours. However, a few bands of snow will push through KRWL, KLAR, and possibly KCYS between 02z and 09z Tuesday with a few hours of MVFR to near IFR VIS due to moderate snowfall. Not extremely confident on the timing, so included a few TEMPO groups for now. This activity should push east and dissipate by 12Z Tuesday morning. && .FIRE WEATHER... Issued at 445 AM MST Mon Dec 27 2021 Elevated fire weather conditions are possible on Monday especially in the Nebraska panhandle. Minimum humidity values are expected to drop to around 25%, and possibly lower near the Colorado border. Breezy conditions are expected with southerly winds gusting to 30-35 MPH. A cold front will push through early Tuesday and bring better humidity recoveries, but drier air moving in behind will result in another afternoon of low humidities despite the cold temperatures. Remaining cold on Wednesday before a brief warm up possible on Thursday. Stronger winds are also possible Thursday. && .CYS WATCHES/WARNINGS/ADVISORIES... WY...Winter Storm Warning until 8 AM MST Tuesday for WYZ112-114. NE...None. && SHORT TERM...GCC LONG TERM...RUBIN AVIATION...TJT FIRE WEATHER...MN
Hazardous Weather Outlook National Weather Service Cheyenne WY 400 AM MST Mon Dec 27 2021 NEZ002-003-019>021-054-055-095-096-WYZ101-102-107-108-118-119- 281100- Dawes County-Box Butte County-Scotts Bluff County-Banner County- Morrill County-Kimball County-Cheyenne County- Northern Sioux County-Southern Sioux County- Converse County Lower Elevations-Niobrara County- East Platte County-Goshen County-Central Laramie County- East Laramie County- 400 AM MST Mon Dec 27 2021 This hazardous weather outlook is for portions of panhandle Nebraska...east central Wyoming and southeast Wyoming. .DAY ONE...TODAY AND TONIGHT No hazardous weather is expected at this time. .DAYS TWO THROUGH SEVEN...TUESDAY THROUGH SUNDAY Light snow and much colder temperatures are possible Friday into Saturday. .Spotter information statement... Spotter activation will not be needed. WYZ103>106-109>111-113-115>117-281100- North Laramie Range-Ferris/Seminoe/Shirley Mountains- Shirley Basin-Central Laramie Range and Southwest Platte County- Central Carbon County-North Snowy Range Foothills- Southwest Carbon County-Upper North Platte River Basin- Laramie Valley-South Laramie Range-South Laramie Range Foothills- 400 AM MST Mon Dec 27 2021 This hazardous weather outlook is for portions of south central Wyoming and southeast Wyoming. .DAY ONE...TODAY AND TONIGHT Snow showers are expected to develop Monday afternoon into the evening and could bring brief visibility reductions and gusty winds. .DAYS TWO THROUGH SEVEN...TUESDAY THROUGH SUNDAY Snow and much colder temperatures are possible Friday into Saturday. .Spotter information statement... Spotter activation will not be needed. WYZ112-114-281100- Sierra Madre Range-Snowy Range- 400 AM MST Mon Dec 27 2021 This hazardous weather outlook is for portions of south central Wyoming. .DAY ONE...TODAY AND TONIGHT After a brief lull early this morning, snow is expected to pick up in intensity again through tonight in the Snowy and Sierra Madre ranges. The Winter Storm Warning has been extended until 800 AM Tuesday. .DAYS TWO THROUGH SEVEN...TUESDAY THROUGH SUNDAY Light mountain snow is expected to continue through the week, with moderate to heavy snowfall possible on Friday into Saturday. .Spotter information statement... Spotter activation will not be needed.
Special Weather Statement National Weather Service Cheyenne WY 922 PM MST Mon Dec 27 2021 WYZ104-109-110-280630- Ferris/Seminoe/Shirley Mountains-Central Carbon County- North Snowy Range Foothills- Including the cities of Seminoe Dam, Rawlins, Arlington, and Elk Mountain 922 PM MST Mon Dec 27 2021 Brief snow-squall conditions possible over the next few hours as a line of moderate to heavy snowfall moves across Carbon County. Visibilities may drop to near a quarter mile with wind gusts 35 to 45 mph. Be prepared for rapidly changing conditions with falling and blowing snow along portions of Interstate 80 between Rawlins and Arlington. LK
PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE CHEYENNE WY
1021 PM MST MON DEC 27 2021
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
1006 PM NON-TSTM WND GST 3 NW ELK MOUNTAIN 41.72N 106.45W
12/27/2021 M70 MPH CARBON WY MESONET
WYDOT SENSOR NEAR ELK MOUNTAIN.
&&
TTThe national radar mosaic for the moment the first event began.
2 high wind. Local standard time, as filed.
A peak wind gust to 73 MPH was observed at the WYDOT sensor at Walcott Junction (WY15) at 10:22 PM MST.
Multiple WYDOT sensors near Arlington and Elk Mountain along Interstate 80 between Laramie and Rawlins recorded frequent wind gusts 65-75 MPH. The peak wind gust observed was 78 MPH at County Road 402 (WY20) at 10:50 PM MST on 12/27.
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: 991903, 991904.