A Pacific weather system moved into Wyoming and brought heavy snow to the western mountains and valleys. The heaviest snow fell in the Tetons with 22 inches of new snow at the Jackson Hole Mountain Resort.
Every event with a place to put it; 5 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.
A Pacific weather system moved into Wyoming and brought heavy snow to the western mountains and valleys. The heaviest snow fell in the Tetons with 22 inches of new snow at the Jackson Hole Mountain Resort. Over a foot of new snow also fell in portions of Yellowstone Park, the Absarokas, and the western Bighorn Range. For the valleys, up to 14 inches fell in Star Valley and 11 inches in Jackson Hole.
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 5, 1:24 PM MST, 2 hours 36 minutes earlier. Its key messages:
Area Forecast Discussion National Weather Service Riverton WY 124 PM MST Fri Dec 5 2025 .KEY MESSAGES... - Moderate to heavy snowfall will return to western WY this evening persisting through Saturday afternoon. - A Winter Storm Warning has been issued for the western Bighorns due to increased snowfall amounts tonight through Saturday evening. - Strong gusty winds are expected to develop this evening becoming widespread overnight through Saturday morning. - Mild and dry temperatures are forecast to return to locations east of the Divide through the middle of next week. Western WY looks to have another couple chances for additional snow accumulations. && .UPDATE... Issued at 118 PM MST Fri Dec 5 2025 Not much to add regarding the forecast for the short term. Temperatures today will be mild across the state with highs in the upper 30s east of the Divide and low 30s west of the Divide. The main focus over the next 36+ hours will be periods of snow across western WY and portions of northern WY along with strong gusty winds for nearly all the state. Winds will continue to increase this afternoon/evening as a rather potent jet streak moves over the region. 700mb winds are relatively strong especially across southern and northern WY where models show winds of 60 to 70 knots tonight through Saturday morning. However, these winds do look to struggle to translate down to the surface. Hi-res models show near High Wind Criteria at the surface mainly over southern WY and portions of the Upper Wind River Basin and Cody Foothills. Due to this no wind highlights are to be issued at this time. Focusing back on snow not much has changed for western WY with snow expected to increase in intensity by the evening. Moderate to heavy periods of snow will settle in over the west through the overnight into Saturday morning. Snowfall rates are forecast to exceed 1 inch an hour at times mainly across the higher elevations of the Teton, Wyoming, and Salt River Ranges. The one noteworthy deviation compared to the previous discussion is a pretty large jump in QPF and snow across the central and northern Bighorns. Likely due to more favorable orographic dynamics moving into the region overnight. Additional snow amounts through Saturday evening over the Bighorns have now increased to 10 to 18 inches with lesser amounts for southern portions. There will likely be periods of moderate to heavy snowfall with snowfall rates exceeding an inch per hour at times. Due to this the Winter Weather Advisory has been upgraded to a Warning to account for this jump in snow amounts. An additional note is the western foothills of the Bighorns where some banding of snow may setup tonight through Saturday evening. An inch or two of snow over the next 24 hours is definitely possible especially farther east of Greybull. Snow will dissipate over much of the state late Saturday with some light snow showers lingering across the west and Bighorns. The longer range forecast has not changed much with increased chances for gusty winds, mild temperatures, and dry conditions returning to locations east of the Divide. West of the Divide looks to see more chances for additional snowfall periodically through the week. && .DISCUSSION... Issued at 343 AM MST Fri Dec 5 2025 Northwest flow aloft, evident on 10Z water vapor imagery, will continue through late Saturday night with multiple embedded disturbances. These disturbances will be the drivers of the meaningful snow across western Wyoming and the widespread gusty winds. The snow will be first up for discussion. Moderate snow will continue to fall across western Wyoming and portions of eastern Sweetwater County through sunrise this morning as a vorticity maxima exits the region. However, there is high confidence (90%+) in snow lightening in intensity across western Wyoming between 8AM and 2PM local today. This "break" in moderate to heavy snowfall is a result of a shortwave aloft bringing in slightly drier air due to its origin over western Canada. Snow is forecast to continue to fall due to Wyoming being in the right entrance region of an approaching strong upper level jet. Snow amounts during this lighter snowfall period will be limited. There is a 40% to 60% chance of at least 1 inch across Jackson and Star Valleys and much of Yellowstone during this 6 hour period. Amounts across the western mountains are forecast to be between 3 and 8 inches, with up to 12 inches across the highest elevations. There is high confidence (80-90%) in moderate to heavy snowfall beginning this afternoon (2-3PM local) across western Wyoming and the west Bighorns. This uptick in snow intensity occurs as the upper level jet moves overhead and another, more potent shortwave brings abundant moisture into the region. Expect the greatest snowfall accumulations to occur between 2-3PM today and sunrise Saturday. Snowfall amounts during this timeframe across the Teton and Gros Ventre Mountains and the Salt River and Wyoming Ranges range from 10 to 15 inches, with 2 feet over the highest elevations. Snowfall amounts across Yellowstone, the Absarokas, the western Bighorns, and west Wind River Mountains will likely be anywhere from 4 to 15 inches during the same time frame. The highest elevations of the Absarokas and the Wind River Mountains will likely (80%) see amounts closer to that 15 inch mark. As for Jackson and Star Valleys and the Upper Green River Basin, snow accumulations from 2-3PM today through sunrise Saturday are generally between 2 and 6 inches. Despite the moderate to heavy snowfall expected, these lower accumulations are largely due to temperatures being near to a few degrees above freezing (60-90% chance). Snowfall will decrease in intensity Saturday morning as slightly drier air begins to move in and support aloft weakens. Nonetheless, snow will still be falling during the day Saturday with a few tenths on an inch to 2 inches for the western Valleys, Upper Green River Basin, and most of Yellowstone. The Absarokas, west Wind River Mountains, and the west Bighorns will see 2 to 5 inches of snow (20% chance of greater than 5 inches). The Tetons and Gros Ventre Mountains and the Salt River and Wyoming Ranges will likely (80%) see anywhere from 4 to 8 inches of additional snow during the day on Saturday. This puts the three-day snow totals for these locations between 12 and 20 inches with higher elevations seeing 2 to 3 feet. Now to the wind. A tightening pressure gradient during the daylight hours today will favor gusty 20 to 30 winds across southern Wyoming and the Absarokas. However, as the aforementioned upper level jet with speeds of 120 to 135kts moves over Wyoming after sunset today, gusty winds increase across much the area. There is good consensus that 700mb winds of 50 kts will be over the western mountains, Sweetwater County, the Wind River Basin, the eastern Bighorn Basin, and northern Johnson County after 10PM tonight through Saturday morning. 700mb wind speeds of this magnitude would normally translate to wind gusts of 60 mph (High Wind Criteria). However, there is currently a 50/50 shot of this occurring in these locations, especially Sweetwater County. The uncertainty is due to Wyoming being in the proximity of the right entrance region of the upper level jet (upward motion as opposed to downward motion) and a diurnal inversion limiting the amount of wind making it to the surface. However, it will still be windy overnight tonight with a 60% to 80% chance of gusts between 40 and 50 mph. The greatest area of concern for gusts around 60 mph is Sweetwater County, where there is only a 30% chance of 60 mph gusts. Given the uncertainty, no wind highlights have been issued at this time. By mid-morning Saturday, the upper-level jet, although weaker (around 100 kts), will be focused over southern portions with associated 700mb winds around 30kts. This will keep much of southern Wyoming gusty on Saturday. There is good agreement among model guidance that drier air will begin to move over Wyoming Sunday morning with overall height rises. This will keep snow chances (40-50%) confined to the western Wyoming with dry conditions elsewhere. There is also agreement that a weak cold front will pass through early Monday bringing additional precipitation chances (80%) for the west. However, this front will not impact temperatures for early next week as above normal temperatures are looking likely (80 to 90%) for mid December. && .AVIATION /18Z TAFS THROUGH 18Z SATURDAY/... Issued at 1114 AM MST Fri Dec 5 2025 West of the Divide...KBPI/KJAC/KPNA/KRKS Terminals. A winter storm will continue to impact terminals across western Wyoming. KJAC will begin the period VFR/MVFR before another push of persistent snow moves in around 22Z. IFR conditions are then expected to persist at KJAC through around 08Z Saturday before an improvement to MVFR with lingering snow through the end of the period. KBPI and KPNA will also see periods of MVFR/IFR tonight. KRKS should miss out on the worst of the snow but should still see MVFR impacts. All terminals will see an accompanying gusty wind, especially at KRKS which will see gusts to 40 knots after 06Z. East of the Divide...KCOD/KCPR/KLND/KRIW/KWRL Terminals. Wind will be the primary aviation concern east of the Divide as most of the snow stays west. The strongest wind will come overnight tonight through much of the rest of the period, most notable at KCPR which will see gusts over 30 knots. Some snow will make it east of the Divide, leading to occasional impacts at or near terminals with the best chances at KCOD, KCPR, and KWRL after 04Z. Please see the Aviation Weather Center and/or CWSU ZDV and ZLC for the latest information on icing and turbulence forecasts. && .RIW WATCHES/WARNINGS/ADVISORIES... Winter Weather Advisory until 2 PM MST Saturday for WYZ001-002- 013-014-023-025. Winter Storm Warning until 5 PM MST Saturday for WYZ008. Winter Storm Warning until 2 PM MST Saturday for WYZ012-024. && UPDATE...Dziewaltowski DISCUSSION...Gerhardt AVIATION...Myers
Hazardous Weather Outlook...CORRECTED National Weather Service Riverton WY 254 AM MST Fri Dec 5 2025 WYZ001>020-022>030-061400- Yellowstone National Park-Absaroka Mountains-Cody Foothills- North Bighorn Basin-Southwest Bighorn Basin-Southeast Bighorn 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- 254 AM MST Fri Dec 5 2025 ...WINTER STORM WARNING REMAINS IN EFFECT FOR THE TETON AND GROS VENTRE MOUNTAINS AND THE SALT RIVER AND WYOMING RANGES UNTIL 2 PM MST SATURDAY... ...WINTER WEATHER ADVISORY REMAINS IN EFFECT FOR YELLOWSTONE NATIONAL PARK AND THE ABSAROKA MOUNTAINS UNTIL 2 PM MST SATURDAY... ...WINTER WEATHER ADVISORY REMAINS IN EFFECT FOR THE BIGHORN MOUNTAINS WEST UNTIL 2 PM MST SATURDAY... ...WINTER WEATHER ADVISORY REMAINS IN EFFECT FOR THE UPPER GREEN RIVER BASIN FOOTHILLS AND WIND RIVER MOUNTAINS WEST UNTIL 2 PM MST SATURDAY... ...WINTER WEATHER ADVISORY REMAINS IN EFFECT FOR JACKSON HOLE AND STAR VALLEY UNTIL 2 PM MST SATURDAY... This Hazardous Weather Outlook is for Western and Central Wyoming. .DAY ONE...Today and tonight. Moderate to heavy snow this afternoon through the overnight hours across the Western Mountains, Jackson and Star Valleys, the Upper Green River Basin, and the northern portions of the western Bighorns. Gusty winds combined with heavy snow could cause reduced visibilities and hazardous travel. Widespread breezy to gusty winds across much of the area this afternoon, with gusts up to 30 mph across the Wind Corridor, the Absarokas, and eastern Wind River Mountains. Wind gusts of 40 to 50 mph are expected after sunset across the western mountains, the Wind Corridor, and the Wind River Basin. .DAYS TWO THROUGH SEVEN...Saturday through Thursday. Saturday...Light snow across western Wyoming and the western Bighorns. Gusty across the area. Wind gusts of 40 to 50 mph across the western mountains, northern Johnson County, the Wind River Basin, and southern Wyoming. Gusts of 60 mph are possible in wind prone locations, especially Sweetwater County. Sunday through Thursday...Multiple chances for snow across western Wyoming and widespread breezy to gusty winds. .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.
5 winter storm. Local standard time, as filed.
Heavy snow fell in the Jackson Valley with 11 inches of new snow 5 miles northwest of Jackson. Jackson town had 6 to 8 inches of snow reported.
Heavy snow fell in portions of the Star Valley, including 14 inches southeast of Smoot and 10 inches near Thayne.
Heavy snow fell along the western slopes of the Bighorn Range, with a maximum of 15 inches of snow at the Bone Springs Divide SNOTEL site.
Heavy snow fell in the Tetons, with a maximum of 22 inches of snow at the Jackson Hole Ski Resort.
Heavy snow fell throughout the Salt and Wyoming Range, with a maximum amount of 20 inches at the Spring Creek Divide SNOTEL site.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Wyoming in 2025Every state in 2025This day in weather historyWarnings in Wyoming, December 2025
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: 1306227, 1306228, 1306225, 1306226, 1306229.