Southwest flow increased ahead of a storm moving into western Wyoming and brought high winds to the Green and Rattllesnake Range. Unlike most events, the strong winds mixed down to the lower elevations, including along Highway 287.
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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.
Southwest flow increased ahead of a storm moving into western Wyoming and brought high winds to the Green and Rattllesnake Range. Unlike most events, the strong winds mixed down to the lower elevations, including along Highway 287. A maximum wind gust of 74 mph was recorded at Jeffrey City.
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 31, 3:43 AM MST, 2 hours 17 minutes earlier.
Area Forecast Discussion National Weather Service Riverton WY 343 AM MST Tue Dec 31 2019 .SHORT TERM...(Today through Wednesday) Issued at 217 AM MST Tue Dec 31 2019 Today will continue the trend of cold and dry weather. This afternoon will see strong winds across the Wind Corridor from the Green Mountains to southern Johnson County. In Natrona County winds could gust as high as 40 mph. Winds will also begin to increase near the Cody/Clark area and the Upper Wind River Basin this afternoon and continue into Wednesday morning, to start the new year. Wind gusts of 50 to 60 mph could occur in the predawn hours Wednesday morning near Clark. The increase in winds to these wind prone locations will be due to the nose of the Polar Front Jet beginning to enter over northwest/western portions of the state tonight/Wednesday morning. The jet will also bring Pacific moisture to western portions. Snow chances will begin to increase Tuesday evening, with snow becoming likely just in time to ring in the new year. We have upgraded all watches to warnings in the Teton, Gros Ventre, Salt, and Wyoming Ranges as well as the Star and Jackson Valleys. Snow totals in the Absarokas and in Yellowstone NP remained lower so we went with and advisory for those areas. We also extended all highlights into Thursday morning. .LONG TERM...(Wednesday night through Monday) Issued at 217 AM MST Tue Dec 31 2019 The H5 trough will be passing across the region Wednesday night into Thursday, with dominant northwest flow continuing across the state into the upcoming weekend. This upper flow will continue to provide favorable conditions for light snowfall for far NW WY Wednesday night through the rest of the week. A clipper system will race across the Northern Plains Thursday, which will switch surface winds back from the west and northwest. Gradient noted between here and the passing system is strong enough to bring gusty winds to most areas during the day Thursday, blowing around any remaining accumulated snowfall. Winds swap right back around from the southwest Friday and Saturday, which will erode some of the valley cold pools, bringing temperatures into the 30s for most areas, well above normal. During the day Saturday, the midlevel flow switches more from due west, as the ridge axis moves to the east of WY. Embedded in this flow is another fast-moving wave, which will provide one more chance for snows for the NW mountains on Sunday, and will allow surface winds to relax some. && .AVIATION...(For the 12Z TAFS through 12Z Wednesday morning) Issued at 217 AM MST Tue Dec 31 2019 East of the Divide...KCOD/KCPR/KLND/KRIW/KWRL Terminals VFR conditions will occur at the terminal sites through the period. Windy conditions at KCPR airport will occur for most of the period. The wind will increase at the KCOD airport after 18Z with higher wind speeds after 02Z. West of the Divide...KBPI/KJAC/KPNA/KRKS Terminals Patchy fog will occur in southwest WY until 17Z with IFR conditions, but not expecting fog at the terminal sites. Otherwise, VFR conditions will prevail at the terminal sites through 00Z. Isolated snow showers will develop in NW WY after 18Z. After 00Z, snow will gradually increase in the western WY mountains with MVFR to IFR conditions developing. KJAC airport will see MVFR conditions after 02Z with snow developing toward 06Z. Expect frequent mountain obscuration after 03Z. Please see the Aviation Weather Center and/or CWSU ZDV and ZLC for the latest information on icing and turbulence forecasts. && .FIRE WEATHER... Issued AT 217 AM MST Tue Dec 31 2019 Cold and dry conditions, with light winds across most of the area today. Southwest winds with gusts of 30 to 40 mph will occur this afternoon across the Wind Corridor from the Green Mountains through southern Johnson County, continuing tonight into Wednesday. These winds will spread into Sweetwater County Wednesday afternoon. Strong winds will also occur in the Absaroka Mountains and Cody Foothills late Tonight into Wednesday with gusts as high as 65 mph in the mountains and 55 mph in the foothills. The next weather system arrives late tonight in the northwest, spreading south across areas west of the Divide through the day Wednesday. && .RIW WATCHES/WARNINGS/ADVISORIES... Winter Weather Advisory from 11 PM this evening to 5 AM MST Thursday for WYZ001-002-025. Winter Storm Warning from 11 PM this evening to 5 AM MST Thursday for WYZ012-013-023-024. && SHORT TERM...Hulme LONG TERM...Straub AVIATION...AR/Hulme FIRE WEATHER...Hulme
Hazardous Weather Outlook National Weather Service Riverton WY 437 AM MST Tue Dec 31 2019 WYZ001>020-022>030-011145- 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- 437 AM MST Tue Dec 31 2019 ...Winter Storm Warnings and Winter Weather Advisories in Effect from 11 PM Tuesday to 5 AM Thursday for the Western Mountains and Valleys... This Hazardous Weather Outlook is for Western and Central Wyoming. .DAY ONE...Today and Tonight. Gusty winds are expected to increase in the wind corridor from Rock Springs to Casper. Winds will reach 30 to 40 mph during the afternoon and overnight. .DAYS TWO THROUGH SEVEN...Wednesday through Monday. New Year's Day...Snow will become widespread across the northwest mountains and valleys early with light snow spreading into southwest and northern Wyoming later in the day. Strong winds are expected in the Cody Foothills with gusts as high as 55 mph and in the Wind Corridor from Rock Springs to Casper with gusts as high as 45 mph. Thursday through Saturday...Snow will continue in the west and southwest with increasingly gusty winds. The strongest wind will be Friday afternoon in the mountains and foothills as well as the wind corridor from Rock Springs to Casper. .SPOTTER INFORMATION STATEMENT... Weather spotters are encourage to report snowfall totals, high wind gusts, and hazardous weather impacts.
Special Weather Statement National Weather Service Riverton WY 231 AM MST Tue Dec 31 2019 WYZ003-010100- Cody Foothills- Including the cities of Clark, Cody, and Meeteetse 231 AM MST Tue Dec 31 2019 ...Strong Gusty Winds Tuesday Night... This is a special weather statement from the National Weather Service Office in Riverton. * WHAT...West to southwest winds 30 to 40 mph with gusts up to 55 mph. * WHERE...The Cody/Clark area. * WHEN...Tuesday night into Wednesday. * ADDITIONAL DETAILS...Travel could be difficult over Highway 120, especially for high profile vehicles. Strong cross winds will enhance the blowover risk for lightweight and high profile vehicles, including camping trailers. Gusts up to 60 also possible near Clark.
Special Weather Statement National Weather Service Riverton WY 418 AM MST Tue Dec 31 2019 WYZ028>030-311600- Rock Springs and Green River-Flaming Gorge-East Sweetwater County- Including the cities of Rock Springs, Green River, and Wamsutter 418 AM MST Tue Dec 31 2019 ...Fog occurring across Sweetwater County this morning... Patchy areas of fog have developed in the lower elevations west of the Continental Divide and will persist through mid-morning. * WHAT...Patchy fog with visibility less than one-half mile at times. * WHERE...Portions of Sweetwater County along Interstate 80 and Highway 191. * WHEN...Through mid-morning Tuesday. * ADDITIONAL DETAILS...Motorists on Interstate 80 and U.S. Highway 191 should be prepared for sudden reductions in visibility. PRECAUTIONARY/PREPAREDNESS ACTIONS... If driving, slow down, use your low-beam headlights, and leave plenty of distance ahead of you.
The national radar mosaic for the moment the first event began.
1 high wind. Local standard time, as filed.
High winds occurred in some areas in the Green Mountains and Rattlesnake Range. The maximum wind gust was 74 mph at Jeffrey City.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Wyoming in 2019Every state in 2019This day in weather historyWarnings in Wyoming, December 2019
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: 868609.