Another Pacific front with decent jet dynamics brought heavy snow to portions of the western Wyoming mountains and strong winds in portions of central Wyoming. New snowfall amounts eclipsed 18 inches in portions of the western mountains with some notable amounts including 2 feet at the Jackson Hole Ski Resort, 22 inches at Blind Bull Summit in the Salt and Wyoming Range and 20 inches at the Two…
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The episode as NWS RIW wrote it up.
Another Pacific front with decent jet dynamics brought heavy snow to portions of the western Wyoming mountains and strong winds in portions of central Wyoming. New snowfall amounts eclipsed 18 inches in portions of the western mountains with some notable amounts including 2 feet at the Jackson Hole Ski Resort, 22 inches at Blind Bull Summit in the Salt and Wyoming Range and 20 inches at the Two Ocean Plateau in Yellowstone Park. Meanwhile, East of the Divide strong winds were the main concern. Wind gusts past 58 mph were recorded in portions of Park, Johnson, Natrona and Fremont Counties.
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 Nov 15, 10:12 PM MST, 1 hour 48 minutes earlier.
Area Forecast Discussion National Weather Service Riverton WY 1012 PM MST Wed Nov 15 2017 .UPDATE...With strong winds showing up close to mountain top level over the Wind River Mountains and a drying signature showing up on water vapor imagery, we have decided to upgrade the high wind watch in the Lander Foothills to a warning. .SHORT TERM...(This evening through Saturday) Issued at 129 PM MST Wed Nov 15 2017 Very active period coming up as next storm bears down on the area later tonight through Friday. Valley rain or rain and snow mixed moves into the far west tonight with snow in the mountains (above 7K or so north to 8-8.5k in the sw). Challenging pcpn type forecast initially in the Jackson valley as temperatures start chilly this evening before winds mix the atmosphere and likely warm the area up a few degrees. Could see more snow early then rain later in the night (with rain/snow mixture above 7k). Mostly rain Thursday then before colder air with the front arrives in the evening. All snow in the mountains Thursday above 7-8k (from north to south) with some decent accumulation. Best snowfall rates still look to be Thursday night and Friday as cold front and trough dynamics arrive. Steep lapse rates and low li's will set the stage for these dynamics to work on along with optimal dendritic growth zone temps where the max omega is. Snowfall rates could be quite impressive in this period. Favored WNW areas could see some impressive snowfall rates continue much of the day Friday (Tetons, Alpine, Togwotee Pass) so extended the highlights through the afternoon Friday. Added in the rest of the western mountains to various watches and advisories during this period. Also decided to throw in the Star Valley for later Thursday evening through Friday with cold air rushing in and favored moist w- nw flow with steep lapse rates and low to even slightly negative li's to aid in heavier snow showers. Thursday is messy in the far nw (YNP and the Absarokas) as the lower elevations will be more rain with heavy wet snow in the mountains. Will try to indicate this in the statement. All areas will changeover to snow at some point Thursday night with snow (showers) through Friday across much of the area. East of the divide, we'll see increasing wind along the Cody Foothills tonight with potential (likely) mountain wave event as jet passes just to the north and favorable mountain top flow aids in rapid increase in foothills winds tonight into Thursday morning. Winds start to break into the foothills after midnight and then further onto the lower elevations. At least that's the peak period from what we're seeing. Continuing until shortly after sunrise. Another area to be watched is the Lander Foothills from about 09-15z late tonight/Thursday morning. Similar situation to the Cody Foothills with favorable sw flow and very strong mountain top flows that may sink/break into the Lander Foothills as jet support passes to the north and provided some sinking motion. High wind watch covers this potential. Wind corridor looks windy tomorrow for all areas but high wind potential seems marginal. Fales Rock/Camp Creek and probably Outer Drive in Casper but other areas seem marginal. Kept the watch out for now to let the next crew give it another look. Friday will be dramatic change east of the divide after a warm and windy Thursday. The front will usher in much colder conditions and areas of snow and strong wind. The I80 corridor looks quite windy with a period of snow much of Friday. The far north also looks like another area to watch for accumulating snow. It'll be cold enough for snow in most everywhere east of the divide Friday so we'll have to watch for concentrated areas of snow showers and convergence areas. The nrn front will be pushing south through the north and into the central zones while the Pacific front ushers in the cold, westerly winds to the south half (and snow). Clearing Friday night with a cold start Saturday. Ridging begins to build then for the remainder of the weekend. .LONG TERM...(Saturday night through Wednesday) Issued at 129 PM MST Wed Nov 15 2017 For the second half of the weekend, a flattening ridge will build in from the west for a dry day on Sunday with seasonably cool temperatures. Then on Monday, the westerly flow will increase and become increasingly difluent as the pressure gradient tightens ahead of the next approaching Pacific trough. The GFS and Canadian are similar in keeping more of the energy from this next trough across the Northern Rockies with most of the energy glancing the area on Monday night with the GFS tracking the trough a little faster than the Canadian. The Euro splits the energy taking a the southern piece of energy across the Four corners area. In any event, will keep chc pops in the far west from Monday through Tuesday night as this weak trough tracks east across the area as the flow remains zonal. The precip will fall in the form of light rain and snow in the lower elevations and light snow in the mtns. An ACT cool front will drop down on Tuesday, but since the weather system will originate over the Pacific, not much of a drop in temps are anticipated. Most of the energy from this system will remain well to our north with the mean ridge over the Western United States framed by a long wave trough off the Pacific coast at 140w and the other over the East Coast. Next Wednesday will feature dry weather across the CWA as the ridge retrogrades to the west of us keeping us under nw flow along with seasonably cool temps (slightly milder than this weekend) and no precip. && .AVIATION...(For the 06Z TAFS through 06Z Thursday evening) Issued at 1000 PM MST Wed Nov 15 2017 West of the Divide...KBPI/KJAC/KPNA/KRKS Terminals A rain snow mix continues for KJAC late this evening, and is expected to continue overnight. Temperatures are expected to remain at or above freezing around KJAC, so little to some accumulation is expected, although MVFR with brief IFR conditions should continue throughout the forecast period. KBPI and KPNA will see MVFR conditions with a rain/snow mix from ~15Z Thu through 00Z Fri. The pre-frontal pattern should keep SW wind in the upper Green River basin. KRKS should remain mostly VFR, with MVFR likely for a few hours Thursday afternoon and early evening as some banded precipitation develops over the airport. Wind gusts at KRKS are likely to exceed 30 knots. Mountains will certainly be obscured throughout the forecast period, and hazardous strong wind is likely over the higher terrain as well. East of the Divide...KCOD/KCPR/KLND/KRIW/KWRL Terminals The largest impact during the forecast period will be strong surface wind and dangerous LLWS around both KCOD and KLND starting 06Z Thu through 15-18Z Thu. The rest of the area east of the divide will see breezy to windy conditions Thursday with gusts over 20 knots, and possibly over 40 knots around KCPR. MVFR conditions should develop around KCOD after 00Z Fri with showers moving off the mountains to the west. With a most fast SW-W flow, the mountains will be obscured through the period. && .FIRE WEATHER... Issued AT 129 PM MST Wed Nov 15 2017 A Pacific front will approach the west tonight and Thursday and spread mountains snow and lower elevation rain, with snow levels falling to the valley floors Thursday night (continuing through Friday). Meanwhile, east of the divide, high winds are likely in the Lee of the Absarokas tonight, possibly along the Lander Foothills and from the Red Desert through Natrona County Thursday. Expect mild temperatures Thursday east of the divide with windy areas followed by a sharp cool down on Friday with windy conditions and a chance of snow. && .RIW WATCHES/WARNINGS/ADVISORIES... Winter Weather Advisory from 5 AM Thursday to 5 PM MST Friday for WYZ002. Winter Storm Watch from late Thursday night through Friday afternoon for WYZ023. High Wind Watch from Thursday morning through Thursday afternoon for WYZ019-020. High Wind Warning from late tonight through Thursday morning for WYZ018. Winter Storm Watch from late tonight through Friday afternoon for WYZ014-024. Winter Storm Warning from midnight tonight to 5 PM MST Friday for WYZ012. Winter Weather Advisory from midnight tonight to 5 PM MST Friday for WYZ001. High Wind Warning from 8 PM this evening to 11 AM MST Thursday for WYZ003. && UPDATE...Hattings SHORT TERM...Skrbac LONG TERM...Lipson AVIATION...Lipson/McDonald FIRE WEATHER...Skrbac
Hazardous Weather Outlook National Weather Service Riverton WY 1014 PM MST Wed Nov 15 2017 WYZ001>020-022>030-170515- 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- 1014 PM MST Wed Nov 15 2017 ...HIGH WIND WARNING FOR THE CODY FOOTHILLS and LANDER FOOTHILLS TONIGHT AND THURSDAY MORNING... ...WINTER STORM WARNING FOR THE TETONS LATE TONIGHT THROUGH FRIDAY... ...A VARIETY OF OTHER WINTER HIGHLIGHTS COVER MUCH OF WESTERN WYOMING THURSDAY THROUGH FRIDAY... ...HIGH WIND WATCHES COVER THE LANDER FOOTHILLS EARLY THURSDAY AND FROM JEFFREY CITY TO CASPER DURING THE DAY ON THURSDAY... This Hazardous Weather Outlook is for Western and Central Wyoming. .DAY ONE...Tonight High winds likely for the Cody Foothills and the Lander Foothills. Snow spreading into the western mountains tonight. .DAYS TWO THROUGH SEVEN...Wednesday through Sunday. Thursday through Friday morning...Snow continuing in the western mountains, rain changing to snow in the valleys Thursday night and Friday. A period of snow is possible along the Interstate 80 corridor Friday and also in the Cody Foothills through the northern Bighorn Basin over to the Buffalo area. High winds likely in the Cody Foothills Thursday morning. High winds are possible across southeastern Fremont County and Natrona County Thursday. .SPOTTER INFORMATION STATEMENT... Spotters are urged to report snowfall amounts and wind gusts above 50 mph. Team Riverton
The national radar mosaic for the moment the first event began.
4 high wind, 2 winter storm, 1 heavy snow. Local standard time, as filed.
Heavy snow fell in southwestern portions of Yellowstone Park. Some of the highest amounts were at the SNOTEL sites at Two Oceans Plateau and Lewis Lake Divide, where 20 and 17 inches fell respectively. Lesser amounts fell at other sites.
Heavy snow fell in many parts of the Tetons. Some of the highest amounts included 24 inches at the top of Jackson Hole Ski Resort and 18 inches at the Togwotee Pass SNOTEL site.
A 59 mph wind gust was reported northwest of Clark.
Heavy snow fell in portions of the Salt and Wyoming Ranges. The highest amount reported was 22 inches at Blind Bull Summit.
The RAWS sites at Camp Creek and Fales Rock reported several hours of wind gusts past 58 mph; including a maximum of 63 mph at both sites.
A 62 mph gust was measured along the North Fork of the Popo Agie River. The ASOS at the Lander airport measured a 60 mph gust.
The ASOS at the Buffalo measured high wind gusts for three hours, including a maximum wind gust of 68 mph.
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, November 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: 723945, 723946, 723948, 723947, 723951, 723950, 723949.