A pair of cold fronts moved across Wyoming and brought areas of heavy snow across northern and western portions of the state. The Big Horn Mountains saw heavy snow with some notable amounts including 20 inches at the Powder River SNOTEL and 16 inches at Shell Creek.
Every event with a place to put it; 9 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 pair of cold fronts moved across Wyoming and brought areas of heavy snow across northern and western portions of the state. The Big Horn Mountains saw heavy snow with some notable amounts including 20 inches at the Powder River SNOTEL and 16 inches at Shell Creek. Some of the other high amounts in the mountains included 19 inches at Evening Star in the Absarokas, 16 inches at Blind Bull Summit in the Salt and Wyoming Range and 13 inches at Togwotee Pass in the Tetons. In the Big Horn Basin, 10 inches of snow fell at Ten Sleep and anywhere from 6 to 9 inches in the Greybull area. In addition, an intense snow squall developed in western Fremont County and moved at speeds of up to 70 mph across the Wind River Basin. Wind gusts of up 77 mph were reported, and the intense winds destroyed a trailer on the Wind River Indian Reservation.
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 Feb 3, 1:40 PM MST, 6 hours 20 minutes earlier.
Area Forecast Discussion National Weather Service Riverton WY 140 PM MST Sat Feb 3 2018 .SHORT TERM...Tonight through Tuesday Quite an active period in store across the area. At the time I write this, there is only light precipitation around the area. However, this will change as an Arctic front drops toward the area from the north and east. This is bringing a tight pressure gradient across the area along with some strong winds, especially across Sweetwater County as well as the Wind River Basin. High winds are not expected except for maybe an isolated gust. It has mixed out some of the basins though. Snow will begin to pick up across the north tonight and drift south, with the worst expected from around midnight until around dawn on Sunday. With the expected dual impacts of wind and snow on Interstate 25, we have expanded the winter weather advisory farther south to include all of Johnson County. Elsewhere, we have held off on highlights. There will be some snow in the Big Horn Basin and Cody Foothills. However, all the models keep the QPF fairly low. If any spot gets advisory level snow it would be areas along and east of Shell and Ten Sleep. We will stick to a special weather statement in the Big Horn Basin. It is the same situation in the western mountains. Some snow will return but most should be of the light to moderate variety. A few locations may get close to advisory amounts but these would be in the higher elevations and have little impact except for fresh powder on the ski slopes. There is still some question how far south the accumulating snow can get. Natrona County will likely see some snow but amounts should remain light. Areas like Riverton and Lander may not get much at all. This snow should end Sunday morning east of the Divide. The next question is temperatures. There could be a LARGE spread across the area. Areas like Buffalo will certainly be cold. There is still uncertainty how far south the cold air can get though. As a result, we kept temperatures fairly close to continuity. Another system will then move in Sunday night into Monday. This looks to bring the heavier snow to the west so some highlights will likely be needed for this time frame, more than likely advisories. Meanwhile, most areas east of the Divide most should see most of the precipitation hold off until Monday. At this point, the models continue to focus on eastern areas from Johnson County into Natrona County for the heaviest snow with less farther west. However, there could be some snow banding that would bring locally heavier amounts. These are impossible to pinpoint this far out though. Most of the steady snow should end late Monday. Ridging will then slowly build across the area and bring drier weather into Tuesday. There could be a few orographic showers but nothing of consequence. It could end up being completely dry as well since the models trend to overdue POPS and QPF in these situations. .LONG TERM...Tuesday Night through Saturday Forecast models are in generally good agreement with the overall evolution of the synoptic pattern. Medium-range period begins with northwest flow aloft prevailing through at least Wednesday night. Conditions will be dry and relatively mild Wednesday and likely into Thursday. West Coast ridge breaks down Thursday into Friday with a trough set to slide southeast across the Intermountain West and northern Rockies. ECMWF has trended slightly faster in bringing this feature through the forecast area late in the day Thursday, but this trend has slowed with the 12Z/Sat run. Trough will sweep across the area Thursday night and Friday accompanied by an Arctic front. Have increased blended west-southwest wind speeds and gusts Thursday afternoon ahead of the front. Did the same with post- frontal northerly winds Thursday night and Friday morning, particularly across northern Wyoming. Favorable mid-level temperatures coupled with the front and upper-level dynamics could set the stage for accumulating snowfall in the basins east of the Continental Divide. We are a long ways out, but the scenario looks plausible. Have substantially increased mountain snow chances in the north along with basin snow chances east of the Divide between 00Z/Fri and 12Z/Fri. Best chances would likely be across the northern-third of the forecast area and in upslope favored central areas. High temperatures will be colder by at least 10-15F Friday behind the front. If the main energy stays just to our west, the front could very well sweep through southwest Wyoming. The snow and clouds will clear from north-to- south later Friday into Friday evening. Thus, temperatures Friday night could be several degrees colder than currently forecast if there is fresh snow cover. Similarly, rebounding temperatures Saturday may be too optimistic given a colder start and fresh snow cover. Drier northwest flow returns for Saturday with dry conditions prevailing. && .AVIATION... West of the Continental Divide...KJAC, KBPI, KPNA, and KRKS Pesky and persistent northwest flow aloft will keep enough moisture streaming into northwest Wyoming to produce light snow in the mountains through 00Z/Mon. Conditions will be MVFR to IFR at KJAC beginning Saturday evening. There appears to be a favored period of more persistent snow at KJAC from 08Z-16Z/Sun. The snow will be accompanied by gusty southerly wind of 12-25kts. The precipitation should decrease Sunday afternoon with rain possibly mixing with the snow. Remaining terminals will generally be dry with scattered snow showers mainly confined to the vicinity of KBPI and KPNA. Upper flow favors gusts west-to-northwest wind with frequent sustained speeds of 15-25kts Sunday afternoon at these sites. Gusts at KRKS could again reach 35-40kts after 19Z/Sun. Mountain tops will be obscured throughout the forecast period. East of the Continental Divide...KCPR, KCOD, KRIW, KLND, and KWRL A cold front will gradually slide south tonight accompanied by light snow and gusty north-to-northwest wind. The best chance for MVFR and IFR conditions will be north of a KCOD-to-KCPR line between 06Z- 15Z/Sun spreading from north-to-south. Mountain tops will be obscured after 06Z/Sun. Conditions look to improve to low-end VFR north of this same line between 15Z-18Z/Sun. KLND and KRIW should remain VFR although a brief MVFR period behind the cold front is possible. The gustiest wind of 20-30kts from the northwest will occur through Saturday evening at KRIW, which is favored in northwest flow aloft. All terminals will trend to VFR after 18Z/Sun. Please see the Aviation Weather Center and/or CWSU ZDV and ZLC for the latest information on icing and turbulence forecasts. && .FIRE WEATHER... A front will drop south across Wyoming tonight into Sunday and bring some snow, heaviest in the north and west. Strong winds will continue in portions of central and southern Wyoming into tonight before decreasing. Drier and cooler weather will return to all areas Sunday afternoon except for the west which could see moderate to heavy snow Sunday night into Monday morning. Mixing and smoke dispersal will range from good in portions of Sweetwater County to fair to poor elsewhere. && .RIW WATCHES/WARNINGS/ADVISORIES... Winter Weather Advisory until noon MST Sunday for WYZ008-009. Winter Weather Advisory until 9 AM MST Sunday for WYZ010-011. && SHORT TERM...Hattings LONG TERM...Jones AVIATION...Jones FIRE WEATHER...Hattings
Hazardous Weather Outlook National Weather Service Riverton WY 346 AM MST Sat Feb 3 2018 WYZ001>020-022>030-041230- 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- 346 AM MST Sat Feb 3 2018 ...Winter Weather Advisory from this afternoon through Sunday morning for the Big Horn Mountains and the lower elevations of northern Johnson County... This Hazardous Weather Outlook is for Western and Central Wyoming. .DAY ONE...Today and Tonight Significant snowfall expected across portions of northern Wyoming later this afternoon into tonight. A cold front will push south into areas east of the divide this evening, with the coldest air expected in Johnson County. Strong west winds are also expected across Sweetwater County today. .DAYS TWO THROUGH SEVEN...Sunday through Friday Sunday and Monday...Significant snowfall expected to extend into Sunday morning across portions of northern Wyoming. Then another round of significant snowfall is expected across western and northern Wyoming Sunday afternoon into Monday. On Monday the snowfall will spread south into central Wyoming east of the divide. Thursday and Friday...A chance of snow across northwest and extreme northern Wyoming Thursday spreading southward Thursday night, before ending on Friday. .SPOTTER INFORMATION STATEMENT... Spotters are encouraged to report any new snow amounts as well as any wind gusts of 45 mph or greater. Thank you. TEAM RIVERTON
The national radar mosaic for the moment the first event began.
6 winter storm, 3 high wind. Local standard time, as filed.
Heavy snow fell along the western slopes of the Big Horns. Some of the higher amounts included 16 inches at Shell Creek and 20 inches at the Cloud Peak SNOTEL.
Heavy snow in eastern portions of the zone, with anywhere from 5 to 10 inches from Lovell to Greybull. Snow amounts dropped rapidly further west.
Heavy snow fell in portions of the Absarokas. Some of the higher snowfall amounts included 19 inches at the Evening Star SNOTEL and 18 inches at the Beartooth Lake SNOTEL.
The SNOTEL at Togwotee pass measured 13 inches of new snow.
Heavy snow fell around Ten Sleep with anywhere from 4 to 10 inches measured. Much less snow fell further west with less than an inch around Worland.
Heavy snow fell in portions of the Salt and Wyoming Range. Some of the higher amounts include 16 inches at Blind Bull Summit and 15 inches at Commissary Ridge.
A narrow and intense snow squall brought a period of high winds to the Upper Wind River Basin. The weather stations at DuBois and Crowheart both reported 60 mph wind gusts.
A narrow and intense snow squall brought high winds to the Wind River Basin. Some of the strongest winds included 77 mph at the Sharpnose RAWS site and 65 mph at the Riverton ASOS.
An intense snow squall brought high winds to the Lander Foothills. The maximum wind gusts recorded was 67 mph at the Lander airport. At Boulder Flats, the high winds ripped the siding and roof off of a mobile home, leaving 21 people temporarily homeless.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Wyoming in 2018Every state in 2018This day in weather historyWarnings in Wyoming, February 2018
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: 738607, 738608, 738606, 738605, 738609, 738610, 738611, 738612, 738613.