A plume of moisture moved into western Wyoming and brought locally heavy snow. The highest amounts were recorded in the Tetons and Salt and Wyoming Range where up to 15 inches of snow fell.
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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 plume of moisture moved into western Wyoming and brought locally heavy snow. The highest amounts were recorded in the Tetons and Salt and Wyoming Range where up to 15 inches of snow fell. Heavy snow also fell in portions of the Star Valley where 8 inches of snow was measured.
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 24, 1:46 PM MST, 7 hours 14 minutes earlier.
Area Forecast Discussion National Weather Service Riverton WY 146 PM MST Sun Dec 24 2017 .SHORT TERM...Tonight through Wednesday Mainly clear skies and cold conditions through the rest of the day today. A stream of clouds and moisture are moving over OR and northern UT. This will shift eastward through the rest of the afternoon, with clouds increasing from southwest to northeast. Precipitation will gradually return to the far west this evening and be ongoing by midnight. Snow will fall across the far west from this time through Christmas night. Although light snow will continue into Tuesday, due to the prolonged favorable NW flow, the heaviest snow will end early Tuesday morning. Snowfall amounts will be similar to this past event from Friday night/Saturday. Another cold front will pass through east of the Divide during the day Monday, before stalling out again across southern portions of Fremont and Natrona counties. As the front progresses southward, areas east of the Divide will be under favorable UL dynamics (relatively moderate UVV) and on the cyclonic side of the jet. Models are not depicting any real chance for snow for this event, however, have added a slight chance to chance PoPs. Gusty winds will also return to the Wind River Mountains and the 287/789 corridor tonight, with gusts of 40 to 45 mph expected. Gusty winds will then return across southern portions Christmas afternoon, with westerly winds gusting 35 to 40 mph. This could cause some areas of blowing snow. As previously mentioned, snow will end across the area late Christmas night/early Tuesday morning. However, NW winds aloft will favor upslope flow across the Northwest. Light snow will be possible through Tuesday and Wednesday. The rest of the area will be dry and cold. .LONG TERM...Wednesday night through Saturday General big picture cyclonic nw flow continues through the medium range period. Multiple embedded disturbances will ride se through this pattern at times while the arctic front generally remains across the nrn and nern/ern zones (Bighorn Basin/Johnson County) setting up a pretty stark contrast at times. Strong nw flow will create areas of strong w-nw flow at times in the mountains, foothills, wind corridor and occasionally spilling onto the lower elevations. However, Snow covered basins (Big Horn/Wind River) will generally remain trapped but there will be wind around the edges for some pretty dramatic temperature variations (and at least some hope of some mixing with passing disturbances and especially ahead of our potential Saturday arctic front and sewd moving shortwave). Most of the snow will fall in the nw mountains in this pattern with some light snow or flurries at times behind the front when the upper shortwaves/jet streaks move through. The GFS has a much more significant (strong upglide with good nw orographic potential)snow event in the far west late Thursday night through Friday night while the Euro/GEM) have more ridging with lighter snows. GFS 5-wave pattern with its cyclonic nw flow would seem to favor at least a potential significant snow event. We still have time to watch it and likely pops for the mountains and chance across the lower elevations will be fine for now. Models vary widely next weekend with timing and location of these sewd moving disturbances/systems and confidence is low on the details this far out. Pattern is conducive to snow out west and arctic boundary hanging around the far ne/nern zones but the daily details will have to be ironed out with time. && .AVIATION...For the 00Z TAFS through 00Z Tuesday West of the Continental Divide...KJAC, KBPI, KPNA and KRKS VFR conditions will prevail at the terminal sites through 06Z. Some snow will develop between 03Z and 06z in Southwest WY with areas of MVFR conditions. Snow will increase in coverage and impact the terminal sites after 06Z Monday through 12Z Monday with MVFR to IFR conditions. Mountains will also become frequently obscured tonight. Christmas day will see widespread snow and mvfr to ifr conds with mtn and hyr trrn obscuration for most of the day. East of the Continental Divide...KCPR, KCOD, KRIW, KLND, and KWRL VFR conditions will prevail at the terminal sites through 12Z Monday. Clouds will lower around KCPR by 11Z Monday with MVFR conditions developing with areas of light snow. Areas of MVFR in cigs and light snow will be possible Christmas afternoon. && .FIRE WEATHER... A transitory area of high pressure will control the weather today and bring dry but cold weather to the area. Inversions will be likely across the basins and the deeper valleys. Mixing and smoke dispersal will be generally fair to poor. The next Pacific system will move into the west tonight but the heaviest precipitation should hold off until after midnight. Another round of moderate to heavy snow will fall across the west, similar to this past Friday/Saturday. Light snow will be possible Christmas and Christmas night across northern and central portions as well. && .RIW WATCHES/WARNINGS/ADVISORIES... Winter Weather Advisory from midnight tonight to midnight MST Monday night for WYZ001-002-014-015-025. Winter Storm Warning from 9 PM this evening to 3 AM MST Tuesday for WYZ012-023-024. Winter Weather Advisory from midnight tonight to 3 AM MST Tuesday for WYZ013. && SHORT TERM...LaVoie LONG TERM...Skrbac AVIATION...Skrbac FIRE WEATHER...LaVoie
Hazardous Weather Outlook National Weather Service Riverton WY 1246 AM MST Sun Dec 24 2017 WYZ001>020-022>030-251215- 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- 1246 AM MST Sun Dec 24 2017 ...Multiple Winter Weather Advisories and Warnings for portions of western Wyoming tonight through tomorrow night... This Hazardous Weather Outlook is for Western and Central Wyoming. .DAY ONE...Today and Tonight. Significant snowfall returning to Western Wyoming tonight, with the heaviest snow after midnight. Please see the the winter storm warnings and winter weather advisories for details. .DAYS TWO THROUGH SEVEN...Monday through Friday. Monday...Significant snowfall likely over portions of western Wyoming. Unseasonably cold temperatures continue across the entire area. Thursday and Friday...Significant snowfall possible across the far west and northwest. .SPOTTER INFORMATION STATEMENT... Spotters are urged to report any snowfall amounts. Thank you. Team Riverton
The national radar mosaic for the moment the first event began.
3 winter storm. Local standard time, as filed.
Heavy snow fell in portions of the Tetons. At the Jackson Hole Ski Resort, 15 inches of new snow was measured.
Around 5 miles south-southeast of Smoot, 8 inches of snow was measured.
At Commissary Ridge, 15 inches of new snow was measured.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Wyoming in 2017Every state in 2017This day in weather historyWarnings in Wyoming, December 2017
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: 728403, 728404, 728405.