A tightening pressure gradient ahead of an advancing cold front increased southwest flow across portions of central Wyoming and brought high winds to some locations. The highest winds were along Wyoming Boulevard south of Casper where winds gusted as high as 74 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 tightening pressure gradient ahead of an advancing cold front increased southwest flow across portions of central Wyoming and brought high winds to some locations. The highest winds were along Wyoming Boulevard south of Casper where winds gusted as high as 74 mph. Strong winds also occurred at the RAWS sites in the Green Mountains with wind gusts to 67 and 63 mph at Fales Rock and Camp Creek, respectively.
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 8, 2:57 PM MST, 1 hour 33 minutes earlier.
Area Forecast Discussion National Weather Service Riverton WY 257 PM MST Mon Jan 8 2018 .SHORT TERM...(Tonight through Thursday) Issued at 254 PM MST Mon Jan 8 2018 Imagery continues to show ridge/trof pattern across the CONUS (west to east) with flat ridging currently in place over WY. Upstream, split flow conditions also continue with the first embedded shortwave/nose of srn branch jet moving through the swrn CONUS and now in UT while the nrn branch of the jet is well up north in Canada with the next and larger embedded wave within a significant trof just offshore BC/WA/OR and coming into the PAC NW. The SFC has high pressure continuing across the intermountain west/central Rockies with lower pressure/frontogenesis (associated with the large offshore trof) beginning develop to the north of cyclogenesis to the south and off the central California coast. Heaviest upstream precipitation now located across srn UT (with the jet) and further west from central California to western OR. West of the Divide: Moisture and clouds will begin to increase today ahead of the southern branch jet/shortwave mentioned above. Continuing WAA will put snow levels out above 7500 today into this evening feet before slowly falling to near the valley floors Tuesday morning with a rain snow mix (possibly all snow if the wet bulb temperatures can stay low enough). The first batch of heavier precipitation will arrive around sunrise Tuesday with moisture making its way into the area from/through central California and Nevada. Rain will possibly mix with snow or turn back to rain in the valleys once again Tuesday afternoon as WAA continues under modest ridging. Then the next and much more impactful moisture arrives Tuesday night, flowing into the region more from the Pacific Northwest. Again, expect more in the way of rain chances below 7000 feet with the changeover from rain to snow at valley locations not a sure thing until early Wednesday morning (precip type largely dependent on just how saturated the lower atmosphere is and what wet bulb temperatures are). This time period with the warmer atmospheric temperatures will also coincide with the heaviest amounts of liquid precipitation...with as much as a half inch possible between midnight tuesday and sunrise Wednesday. This could correlate to as much as 4 to 8 inches during that (roughly) 6 hour period...with 2 to 4 inches preceding and another 2 to 3 Wednesday morning. All told, between later tonight and noon on Wednesday, expecting total snowfall amounts of 8 to 16 inches (locally to 20 inches) in the Teton and Gros Ventre mountains with; 4 to 12 (locally to 16 inches) in the surrounding mountains; and 1 to 4 inches in the area valleys (especially with the rain/snow/rain/snow thing going on). South to southwest winds will also increase west of the Divide with this weather system, especially from Tuesday afternoon through Wednesday morning with gusts ranging from 35 to 55 mph at times across the favored ridges/passes. Lingering areas of light snow showers or flurries will remain over portions of western/northwestern WY Wednesday night. Another winter weather system will begin to make itself known later on Thursday...continuing into/through Friday. East of the Divide: Flat ridging aloft, WAA and lee side troffing will keep the region dry with winds increasing across the usual spots...particularly the Wind Corridor and the eastern Foothill along the Absaroka and Wind River Mountains. High wind conditions will begin to make a racket later tonight through Tuesday night across the Wind Corridor as the SFC P Grad increases and combines with relatively strong winds just off the surface. However, it will remain mostly dry east of the Divide until Wednesday when the entire FA begins to feel the effects of the upper trof and an associated strong cold front pushing south across the region. Snow will come mainly along and behind the front Wednesday afternoon and evening with some areas of rain or rain mixed with snow for a short period of time. Possible Advisory or near Advisory level snow or impacts will be possible east of the divide, particularly across the Cody Foothills in addition to portions of Johnson and Natrona Counties with 1 to 3 inches of snow mixing with gusty north winds causing slick/icy roads and reduced visibilities into Wednesday evening. Will continue to evaluate. Thursday into Thursday night, strong winds will return to the foothills and Wind corridor once again...a prelude to the next winter system due to arrive later Thursday night through Friday. .LONG TERM...(Thursday night through Monday) Issued at 254 PM MST Mon Jan 8 2018 Synopsis...The region will be dominated by NW flow aloft, as a longwave ridge remains centered over the WCONUS. This ridge will begin to break down by Monday night. In the meantime, a Pacific system will bring widespread snow to the forecast area Thursday night through Friday, with lingering snow across the north Friday night. A second, possibly Arctic system will bring another shot of snow east of the Divide Sunday night into Monday. Discussion...Gusty winds will occur in wind prone locations, especially east of the Divide, at the beginning of the forecast period. This will be as a result of the approaching cold front. W-NW winds of 30 to 45 mph with gusts up to 55 mph will be possible across the I-80 corridor Friday afternoon. The best chances for snow will be across the northern and western mountains once again, with isolated to scattered chances east of the Divide during the day Friday. Conditions will be mainly dry Saturday and Sunday, with partly to mostly cloudy skies and generally light winds. Have gone with isolated to scattered PoPs across northern and central portions Sunday night into Monday for now. Temperatures will remain seasonal for through the period as well. && .AVIATION...(For the 00Z TAFS through 00Z Tuesday evening) Issued at 254 PM MST Mon Jan 8 2018 West of the Continental Divide...KJAC, KBPI, KPNA and KRKS VFR conditions with light winds are expected to remain at area terminals, with considerable mid-high level cloudiness overspreading the region. Deteriorating conditions are expected between 03Z and 08Z, with MVFR ceilings and some IFR visibilities in snow developing mainly along and northwest of a KEMM to 30N KRKS line. These conditions will marginally improve after 18Z Tuesday with MVFR conditions, while IFR visibilities continue at KJAC. East of the Continental Divide...KCPR, KCOD, KRIW, KLND, and KWRL The main concern will continue to be LLWS and turbulence on the lee side of mountain ranges, and the windy southwest wind between South Pass and Casper. Even in times where LLWS is not expected at KCOD, LLWS conditions will be marginal. Otherwise, VFR conditions with considerable lee enhanced clouds with light winds in the central basins. Tonight expect increasing mid-level cloudiness, with snow developing along the Divide and points west. Please see the Aviation Weather Center for the latest information on icing and turbulence forecasts. && .FIRE WEATHER... Issued AT 254 PM MST Mon Jan 8 2018 Today through the end of the work week, a couple of strong winter weather systems will impact the forecast area with heavy snow and blustery winds at times west of the Divide; strong winds tonight through Tuesday night across the usual windy spots east of the Divide; and light snow and gusty north winds on Wednesday and Friday east of the Divide. As much as 1 to 2 feet of snow will be possible in the mountains of the west above 7500 feet through Wednesday with more to follow later Thursday and Friday. Smoke dispersion will poor to fair for most locations today, fair to good Tuesday and good to very good on Wednesday. && .RIW WATCHES/WARNINGS/ADVISORIES... Winter Weather Advisory from 5 AM Tuesday to noon MST Wednesday for WYZ001-002. High Wind Warning from 9 PM this evening to midnight MST Tuesday night for WYZ019-020. Winter Weather Advisory from midnight tonight to noon MST Wednesday for WYZ014-015-024. Winter Storm Warning from midnight tonight to noon MST Wednesday for WYZ012. && SHORT TERM...Braun LONG TERM...LaVoie AVIATION...LaVoie FIRE WEATHER...Braun
Hazardous Weather Outlook National Weather Service Riverton WY 304 PM MST Mon Jan 8 2018 WYZ001>020-022>030-092215- 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- 304 PM MST Mon Jan 8 2018 ...High Wind Warning for the Southern Wind Corridor from Jeffrey City to Casper for tonight through Tuesday evening... ...Winter Storm Warning for the Teton and Gros Ventre Range for late tonight through Wednesday morning... ...Winter Weather Advisories for Yellowstone NP, the Absaroka Mountains, the Salt River Mountains, and the Wyoming Mountains from late tonight through Wednesday morning... This Hazardous Weather Outlook is for Western and Central Wyoming. .DAY ONE...Today and Tonight. Light snowfall will develop over far Western Wyoming later this evening, becoming heavier toward morning. .DAYS TWO THROUGH SEVEN...Tuesday through Sunday. Tuesday and Wednesday...Accumulating snowfall across the south and west Tuesday through Wednesday morning. A cold front will spread areas of snow south across northern and central Wyoming Wednesday morning east of the divide with the main travel impacts expected along Interstate 25 from Buffalo to Casper. Snow will taper off west to east Wednesday night. High winds are possible from Jeffrey City to Casper for tonight through Wednesday morning. Thursday night and Friday morning...Another upper level disturbance will spread snow into the west, with snow also developing across portions of central Wyoming early Friday. Locally heavy snow is possible. .SPOTTER INFORMATION STATEMENT... Spotters are encouraged to report wind gusts of 50 mph as well as any snowfall amounts. Thank you.
Special Weather Statement National Weather Service Riverton WY 317 PM MST Mon Jan 8 2018 WYZ013-016-023-025-091000- Jackson Hole-Upper Wind River Basin-Star Valley- Upper Green River Basin Foothills- Including the cities of Jackson, Dubois, Afton, Alpine, Star Valley Ranch, Thayne, and Pinedale 317 PM MST Mon Jan 8 2018 ...Significant snowfall likely for far Western Wyoming tonight through Wednesday... A series of Pacific weather disturbances will be delivering periods of snowfall to far Western Wyoming beginning this evening and continuing through Wednesday. The snowfall will start off as light rain or rain mixed with snow below 7500 feet later tonight, but will become heavier in intensity and reach to the valley floors at times Tuesday through Wednesday. The heaviest snowfall will likely occur Tuesday night through Wednesday morning. Rain may mix in with the snow again Tuesday afternoon and evening in the western valleys. By the end of Wednesday expect from 1 to 4 inches of snowfall to accumulate in the valleys and foothills...locally to 5 or 6 inches in the eastern Star Valley and northern Upper Green River Foothills. Stay tuned for additional statements along with warnings or advisories concerning this anticipated snowfall event. WYZ003-091000- Cody Foothills- Including the cities of Cody and Meeteetse 317 PM MST Mon Jan 8 2018 ...Occasional Strong Winds at Times in the Cody Foothills Tuesday and Tuesday night... Occasional west to southwest winds will blow at 20 to 30 mph with gusts 45 to 55 mph Tuesday and Tuesday night before decreasing Wednesday morning. These strong winds will occur across portions of the western foothills...particularly in vicinity of Clark where localized gusts of 60 to 70 mph will be possible. Sudden, strong cross winds will enhance a blow over risk for light weight high profile vehicles, especially from Clark southward along highway 120 to the intersection with highway 296.
The national radar mosaic for the moment the first event began.
2 high wind. Local standard time, as filed.
The WYDOT weather sensor along Wyoming Boulevard south of Casper saw numerous wind gusts over 58 mph, including a maximum of 74 mph.
The RAWS sites at Fales Rock and Camp Creek saw wind gusts 67 and 63 mph, respectively.
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, January 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: 728995, 728994.