A brief period of strong gap winds developed across the North Snowy Range foothills.
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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 CYS wrote it up.
A brief period of strong gap winds developed across the North Snowy Range foothills.
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 Cheyenne, WY wrote its last area forecast discussion before the first event at Dec 19, 10:35 PM MST, 40 minutes earlier.
Area Forecast Discussion National Weather Service Cheyenne WY 1035 PM MST Tue Dec 19 2017 .UPDATE... Issued at 917 PM MST Tue Dec 19 2017 We are sending out a quick update to upgrade the high wind watch to a high wind warning for Arlington. Latest surface analysis was showing decent pressure falls taking place across northern and central Wyoming in response to jet energy moving in from the southwest. This will continue to increase the gradient across southern Wyoming overnight. && .SHORT TERM...(This evening through Thursday night) Issued at 210 PM MST Tue Dec 19 2017 Concerns will focus on the return to winter weather Weds night through Thursday night along with snowfall. Mainly clear across the CWA this afternoon and this will continue this evening before clouds begin increasing later tonight ahead of an upper trough now impinging along the west coast. Some weak shortwave energy will pass across overnight and should increase the pressure gradient around the mtns so expect winds to increase there, possibly flirting with high wind levels in the wind favored area around Arlington. Have posted a High Wind Watch for that area. Rest of the wind prone areas not looking so likely but still a windy period later tonight into Weds. Continued mild Weds with some gusty winds in a favorable swly flow ahead of the upper trough. Changes begin Weds night with the passage of a strong cold front while the upper trough closes off an upper low over Utah. Surface upslope flow and some upper diffluence expected to spread widespread mainly light snows to the CWA through Thursday, tapering off from NW to SE in the afternoon as the upper system digs over the southern Rockys. Still looking like a general 2-5 inches over the plains with 8-11 over the higher peaks. Some blowing snow likely in spots with a healthy northerly wind later Weds night into Thursday. Quite cold Thursday with max temps in the teens to lower 20s. Clearing out Thursday evening with lighter winds setting up a very cold night with lows below zero likely in low lying areas such as the Laramie Valley. .LONG TERM...(Friday through Tuesday) Issued at 210 PM MST Tue Dec 19 2017 A busy holiday weekend and early next week shaping up with some winter weather headlines to discuss. 12Z numerical models and their ensembles are in good agreement, with the next Arctic air mass plunging south across the CWA Friday night and Saturday, accompanied by widespread snow, very cold temperatures and bitterly cold wind chills. Prior to the frontal passage, there will be a brief temperature moderation with highs mid teens to mid 20s. Snow spreads south across the CWA Friday, continues through Saturday afternoon, and tapers off from north to south by Saturday evening. Snow ratios will be close to 25:1, with accumulations from 1-2 inches western NE, 2-6 inches southeast WY, and 6-8 inches over the mountains. Temperatures will not recover much Saturday, with single digits to lower teens in the afternoon. Wind chill advisories and warnings will become a factor after the snow ends Saturday, and linger into early next week, with blustery north-northwest winds. The coldest ambient temperatures will occur late Saturday night and early Sunday morning, ranging from around 0 to teens below zero west of the Laramie Range, most. Increasing west winds with gusts to 40 mph will drive wind chills to 30 to 40 below zero west of I-25. A rather tight pressure gradient develops by 12Z Sunday morning, with CAG-CPR 700/850mb heights exceeding 50m, and continuing through late Sunday night. Also, 700mb winds increase to 50-55kt Sunday, so high wind headlines may be required for the normally wind prone areas of southeast WY. With the stronger winds, travel impacts from blowing/drifting snow, slick roads, and poor visibilities will need to be considered. Temperatures begin to slowly moderate Christmas Eve and Day as the axis of the coldest air mass gradually shifts east. GFS typically doesn't handle the extent and duration of these Arctic cold outbreaks, and moderates the air mass too quickly. Undercut ECMX MOS high temperatures Monday about 10 degrees, and followed closely for Tuesday. && .AVIATION...(For the 06Z TAFS through 06Z Wednesday night) Issued at 1027 PM MST Tue Dec 19 2017 Latest water vapor loop was showing the upper level trof continuing to dig across the Pacific northwest. As this feature approaches the region, the jet energy will continue to increase across western Wyoming. As a result, this will cause the pressure gradient to continue to increase which will result in strong gusty wind speeds at the KLAR/KRWL TAF sites after 15z. We did bump up wind speeds to reflect this potential. Meanwhile, the cold front is expected to slide through KRWL and northern Nebraska by midnight. Snowfall will also develop behind this boundary and should move into KRWL before 06z tomorrow night. && .FIRE WEATHER... Issued at 210 PM MST Tue Dec 19 2017 One more mild day Weds with some gusty winds around the mtns, then a strong cold front will pass across the area Weds night with much colder temps and snow behind it. Very cold through the weekend with light snow Thursday then again Friday night and Saturday. Fire weather concerns not anticipated. && .CYS WATCHES/WARNINGS/ADVISORIES... WY...High Wind Warning until 10 AM MST Wednesday for WYZ110. NE...None. && UPDATE...REC SHORT TERM...RE LONG TERM...MAJ AVIATION...REC FIRE WEATHER...RE
Hazardous Weather Outlook National Weather Service Cheyenne WY 951 PM MST Tue Dec 19 2017 NEZ002-003-019>021-054-055-095-096-WYZ101>105-107>109-111>115-118- 119-201230- Dawes-Box Butte-Scotts Bluff-Banner-Morrill-Kimball-Cheyenne- North Sioux-South Sioux-Converse County Lower Elevations- Niobrara County-North Laramie Range- Ferris/Seminoe/Shirley Mountains-Shirley Basin-East Platte County- Goshen County-Central Carbon County-Southwest Carbon County- Sierra Madre Range-Upper North Platte River Basin-Snowy Range- Laramie Valley-Central Laramie County-East Laramie County- 951 PM MST Tue Dec 19 2017 This hazardous weather outlook is for portions of western Nebraska...east central Wyoming...south central Wyoming and southeast Wyoming. .DAY ONE...TONIGHT No hazardous weather is expected at this time. .DAYS TWO THROUGH SEVEN...WEDNESDAY THROUGH MONDAY A strong cold front will sweep across the region Wednesday night and Thursday. This front will be accompanied by widespread accumulating snowfall, some drifting snow, and much colder temperatures. Morning lows near zero degrees are possible Friday. An arctic cold front is forecast to move into the region during the weekend bringing more snowfall and the potential for bitter cold temperatures. Those with early holiday travel plans late this week and into the weekend should continue to monitor the latest weather forecasts. .Spotter information statement... Spotter activation will not be needed. WYZ106-110-116-117-201230- Central Laramie Range and Southwest Platte County- North Snowy Range Foothills-South Laramie Range- South Laramie Range Foothills- 951 PM MST Tue Dec 19 2017 This hazardous weather outlook is for portions of south central Wyoming and southeast Wyoming. .DAY ONE...TONIGHT Periods of strong gusty winds are possible across the wind prone areas along Interstate 80, mainly between Laramie and Rawlins. West to southwest winds may gust to 50 to 60 mph at times through tonight. .DAYS TWO THROUGH SEVEN...WEDNESDAY THROUGH MONDAY A strong cold front will sweep across the region Wednesday night and Thursday. This front will be accompanied by widespread accumulating snowfall, some drifting snow, and much colder temperatures. Morning lows near zero degrees are possible Friday. An arctic cold front is forecast to move into the region during the weekend bringing more snowfall and the potential for bitter cold temperatures. Those with early holiday travel plans late this week and into the weekend should continue to monitor the latest weather forecasts. .Spotter information statement... Spotter activation will not be needed.
The national radar mosaic for the moment the first event began.
3 high wind. Local standard time, as filed.
The WYDOT sensor at Arlington measured sustained winds of 40 mph or higher.
The WYDOT sensor at Cooper Cove measured sustained winds of 40 mph or higher, with a peak gust of 60 mph at 20/0805 MST.
The WYDOT sensor at Strouss Hill measured peak wind gust of 58 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, 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: 730744, 730745, 730746.