A tight pressure gradient developed ahead of an advancing cold front and brought high winds to Natrona County. Many location had wind gusts past 58 mph.
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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.
A tight pressure gradient developed ahead of an advancing cold front and brought high winds to Natrona County. Many location had wind gusts past 58 mph. The strongest wind occurred along Wyoming Boulevard south of Casper, Wyoming, where a maximum gust of 79 mph was reported. The Natrona County airport had wind gusts as high as 68 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 Jan 27, 4:16 AM MST, 4 hours 2 minutes earlier.
Area Forecast Discussion National Weather Service Riverton WY 416 AM MST Wed Jan 27 2021 .SHORT TERM...(Today through Thursday) Issued at 256 AM MST Wed Jan 27 2021 An approaching trough will bring two issues concerning the short term forecast. First up will be strong winds across the Wind Corridor beginning this morning as the southwest flow gets established. While locally high wind criteria gusts look possible this afternoon, we expect the more widespread hazard to be blowing snow. While only 1 to 3 inches of snow fell recently across that area, it should be primed to blow as temperatures have stayed well below freezing, keeping it from glazing over. We will be issuing a Winter Weather Advisory for blowing snow across these areas through this evening. Meanwhile, the moist flow will bring snow to the west starting this afternoon. Snow should be light to moderate most of the time, lasting overnight and through Thursday. With southwest flow, the most snow will likely fall over the Winds, Tetons, and southern portions of Yellowstone; have issued a Winter Weather Advisory for these areas and Jackson Hole through Thursday evening. Elsewhere, locations will mainly remain dry, with warmer highs on Thursday as warmer air advects into the area. The gusty southwest wind will remain across the Wind Corridor through the period, but expect the highest winds today. .LONG TERM...(Thursday night through Tuesday) Issued at 256 AM MST Wed Jan 27 2021 Strong southwest flow aloft will occur Thursday night through Friday ahead of a major trough. The trough is expected to split and push across the Rockies Friday night and Saturday with the strongest energy pushing across the southern Rockies. The GFS continues to keep snow over the west, albeit lighter, continuing Thursday night and Friday. On the other hand, the NAM and ECMWF are much drier during this time frame. Models are in agreement with snow returning across the west with the frontal passage Friday night with some lingering snow into Saturday. There could be some aided lift over the west associated with a right-entrance of an upper jet as pulls away from the area late Friday into Friday night. Will probably need highlights for portions of the west with this wave of snowfall. Areas east of the Divide will remain dry through Friday with the central wind corridor remaining breezy. With the frontal passage, areas east of the Divide could see some light snow Friday night and Saturday. Ridging is expected Sunday into Monday with dry conditions expected with seasonal to slightly below average temperatures. Medium range models are in decent agreement with a trough pulling into the Pacific Northwest/N. California Monday night. Models then begin to diverge in the details, but show the general trough pulling into the Rockies Tuesday night and Wednesday. The associated cold front looks to pull across the area Tuesday night/Wednesday morning. Good chances of snow over the west Tuesday. Current model data shows decent chances of snow east of the Divide in the Tuesday night/Wednesday time frame. However this is of course 7 days out. && .AVIATION...(For the 12Z TAFS through 12Z Thursday morning) Issued at 256 AM MST Wed Jan 27 2021 East of the Divide...KCOD/KCPR/KLND/KRIW/KWRL Terminals VFR conditions are expected at area terminals through the period. The main concern will at blowing snow at KCPR from around mid- morning, possibly lasting well into the evening. This blowing snow will be caused by gusty southwest wind gusts up to 40 knots. Visibility at KCPR should remain VFR, but runway conditions could be impacted from the BLSN with partial melting in the afternoon resulting in the potential for some slush developing. West of the Divide...KBPI/KJAC/KPNA/KRKS Terminals Areas of fog/low ceilings/light snow have the potential to impact KBPI, KPNA and KJAC through the morning hours. This will result in MVFR to LIFR conditions. KJAC looks to be mainly MVFR to low VFR during this time frame. Areas of light snow will break out across the far west between 20Z and 22Z, and become widespread during the evening hours. KJAC will be impacted first followed a few hours later by KBPI and KPNA. Periods of snow are then expected through Thursday morning. Would expect a prolonged period of IFR visibility (MVFR ceilings) at KJAC and mainly MVFR conditions at KBPI and KPNA tonight. KRKS is expected to be mainly dry with VFR conditions through the TAF period. Mountains over the west will be partial obscured this morning, but are expected to become totally obscured by late afternoon/early evening. 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 256 AM MST Wed Jan 27 2021 Snow chances will increase across western Wyoming this afternoon and evening and last through the weekend. Southwest winds will become strong this afternoon along the Wind Corridor from Rock Springs to Natrona County. Also expect gusty winds along higher elevations in the mountains. Smoke dispersal will be poor to fair this afternoon, with some areas of good in windier areas. && .RIW WATCHES/WARNINGS/ADVISORIES... Winter Weather Advisory from 9 AM this morning to 10 PM MST this evening for WYZ019-020-022. Winter Weather Advisory from 2 PM this afternoon to 8 PM MST Thursday for WYZ001-012>014. && SHORT TERM...Myers LONG TERM...Murrell AVIATION...Murrell FIRE WEATHER...Myers
Hazardous Weather Outlook National Weather Service Riverton WY 526 AM MST Wed Jan 27 2021 WYZ001>020-022>030-281230- 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- 526 AM MST Wed Jan 27 2021 ...Winter Weather Advisory for Blowing Snow across southeast Fremont and Natrona counties thru this evening... ...Winter Weather Advisory for Significant Snow across the northwest this afternoon thru Thursday evening... This Hazardous Weather Outlook is for Western and Central Wyoming. .DAY ONE...Today and Tonight. Significant blowing snow over southeast Fremont and Natrona counties through this evening. Significant snow expected over the northwest late this afternoon into Thursday. Please see the winter weather statement for more details. .DAYS TWO THROUGH SEVEN...Wednesday through Monday. Thursday...Significant snow continues over the northwest. Friday night and Saturday...Significant snow possible over the west. .SPOTTER INFORMATION STATEMENT... Spotters are encouraged to report any snow amounts.
Special Weather Statement National Weather Service Riverton WY 616 AM MST Wed Jan 27 2021 WYZ023-025-272215- Star Valley-Upper Green River Basin Foothills- Including the cities of Afton, Alpine, Star Valley Ranch, Thayne, and Pinedale 616 AM MST Wed Jan 27 2021 ...Light snow likely today through Thursday... This is a special weather statement from the National Weather Service Office in Riverton. * WHAT...Periods of mainly light snow. 1 to 3 inches likely, with higher amounts in the Bondurant area. * WHERE...Star Valley and the Upper Green River Basin Foothills. This includes Afton, Alpine, Pinedale, and Bondurant. * WHEN...Today through Thursday evening. * ADDITIONAL DETAILS...Expect slick and snow covered roads with decreased visibility at times. WYZ024-272215- Salt River and Wyoming Ranges- 616 AM MST Wed Jan 27 2021 ...Light to moderate snow likely today through Thursday... This is a special weather statement from the National Weather Service Office in Riverton. * WHAT...Periods of light to moderate snow. 3 to 6 inches possible, with locally higher amounts at increased elevation. * WHERE...Salt River and Wyoming mountain ranges. * WHEN...Today through Thursday. * ADDITIONAL DETAILS...Gusty winds may cause blowing snow and reduced visibility at times.
The national radar mosaic for the moment the first event began.
2 high wind. Local standard time, as filed.
Natrona County saw widespread reports of high wind. Some of the highest wind gusts included 79 mph along Wyoming Boulevard and 68 mph at the Natrona County airport.
At the Fales Rock RAWS site, the wind gusted as high as 75 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, January 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: 935880, 935881.