A plume of Pacific moisture and an associated cold front moved across the area and brought heavy snow and strong wind to some areas. Locally heavy snow fell in the Tetons with 16 inches reported at the Jackson Hole Ski Resort.
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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 plume of Pacific moisture and an associated cold front moved across the area and brought heavy snow and strong wind to some areas. Locally heavy snow fell in the Tetons with 16 inches reported at the Jackson Hole Ski Resort. In Natrona County, a tight pressure gradient and strong low level southwesterly winds mixing to the surface brought high winds. A maximum wind gust of 76 mph was reported along Wyoming Boulevard south of Casper with 62 mph wind gusts reported at the Natrona County airport.
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 6, 10:40 PM MST, 3 hours 20 minutes earlier.
Area Forecast Discussion National Weather Service Riverton WY 1040 PM MST Fri Dec 6 2019 .SHORT TERM...This afternoon through Saturday night Mostly clear skies and light winds in place this afternoon across much of the area east of the Divide. Overcast skies remain in place over southern and western portions, minus Sublette County. Gusty winds are now in place near Cody and Casper. Winds near Cody are expected to subside briefly by this evening, before increasing again late tonight. This will be due to a tight temperature gradient that will be in place between the Absarokas/Yellowstone Plateau and the Bighorn Basin. The leeside trough will remain in place through Saturday, which will keep winds gusty over Natrona County. 700mb winds will increase to 50kt over southern portions of the county after 12Z Saturday. Thus, have issued a High Wind Warning for much of Natrona County for much of the day Saturday. Low clouds are expected to continue into this evening, filling in over Sublette County. Areas of fog will be possible once again tonight over portions of Sublette and southern Lincoln counties. Visibilities of 1/2 to 1/4mi are also possible again. Fog will also be possible again tonight in the Wind River Basin. Apart from a slight chance for flurries over portions of Yellowstone, conditions will be dry across the area this afternoon through Saturday morning. Chances for snow will increase over far western portions after 12pm Saturday, as Pacific moisture increases over the area. Ejecting shortwaves from a filling storm system moving over the PACNW will bring the first chances of snow to these areas by Saturday afternoon. Snow levels will range between 7000 and 8000 feet, before falling after sunset. A steady stream of moisture will move over the area, from Yellowstone southward to the Star Valley and the Salt/Wyoming Ranges, Saturday night and through the day on Sunday. Moderate to heavy snow will be possible late Saturday night through Sunday morning, with snow continuing through the day. Snowfall totals up to 6 inches expected in the lower elevations and up to 12 inches in the mountains, especially the Tetons. Thus, Winter Storm Watches are in effect for portions of the far west. .LONG TERM...Sunday through Friday Snow will continue across the west Sunday. Some light snow is likely to spill east of the Divide Sunday night, but accumulations should stay in the trace to 2 inch range, with most locations on the lower end. Snow should be out of the area by sunrise Monday. Meanwhile, a stronger cold front will beckon in colder air across the area, with Monday high temperatures generally 10 to 15 degrees cooler than on Sunday. Gusty winds on Sunday ahead of this front will continue from Rock Springs to Casper. Northwest flow will prevail over the area through Thursday. While most areas will stay dry through the period, the western mountains could see occasional snow showers. The next shot for a more significant system will be towards the end of the period; models are hinting at another weekend snow event across the northwest. && .AVIATION...(For the 06Z TAFS through 06Z Saturday night) Issued at 1140 PM MST Fri Dec 6 2019 Weak high pressure over the area tonight and tomorrow is allowing a variety of weather to impact the terminals. Generally VFR conditions can be expected, though some sites are likely to drop to MVFR and IFR due to fog, starting now through 16z-18z/Sat. Likely sites are KBPI, KPNA, and KRIW, with KLND a possibility too. Windy conditions will persist at KCPR overnight and become stronger Saturday, with gusts likely near 50 kts Sat afternoon. Breezy conditions with gusts to 20-25 kts are also expected at KCOD through Sat. Moisture will move into western WY Sat afternoon to bring snow to the mountains around 18Z, spreading to KJAC between 21z/Sat- 00z/Sun. Western WY mountains are expected to be obscured through much of the forecast period. KRKS and sites east of the divide will be VFR Saturday with just some thick high clouds. && .FIRE WEATHER... Southwest winds 20 to 25 mph with gusts up to 35 mph will continue over zones 280 and 289 through tonight. These winds will increase to 30 to 35 mph with gusts up to 60 mph by sunrise Saturday morning. These winds will continue through the day, before subsiding back down to gusts of 35 mph Saturday evening. These gusty winds will continue Saturday night. Gusty winds will occur over the mountains during this time. Otherwise, winds will generally be light across the area. Clouds and light snow will increase by Saturday afternoon over far western portions, with generally mostly sunny conditions expected east of the Divide. Moderate to heavy snow will occur over the far west Saturday night into Sunday. && .RIW WATCHES/WARNINGS/ADVISORIES... High Wind Warning from 8 AM to 6 PM MST Saturday for WYZ020-022. Winter Storm Watch from Saturday evening through Sunday evening for WYZ023-025. Winter Storm Watch from Saturday afternoon through Sunday evening for WYZ012-013. && SHORT TERM...LaVoie LONG TERM...Myers AVIATION...McDonald FIRE WEATHER...LaVoie
Hazardous Weather Outlook National Weather Service Riverton WY 148 PM MST Fri Dec 6 2019 WYZ001>020-022>030-072100- 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- 148 PM MST Fri Dec 6 2019 ...High Wind Warning across portions of Natrona County Saturday... ...Winter Storm Watch for far western Wyoming Saturday afternoon through Sunday evening... This Hazardous Weather Outlook is for Western and Central Wyoming. .DAY ONE...Tonight. Patchy to areas of freezing fog will be possible over portions of Sublette and southern Lincoln counties, as well as the Wind River Basin. .DAYS TWO THROUGH SEVEN...Saturday through Thursday. Saturday...Patchy fog will remain possible over portions of Sublette and southern Lincoln counties, as well as the Wind River Basin through the late morning. Strong to high winds will occur over portions of Natrona County, including Casper Mountain. Saturday and Sunday...Significant snow possible over the far west as a storm system approaches and moves through the region. Snow will begin by the afternoon and continue through the day Sunday, before gradually ending Sunday night. Tuesday...Strong northwest winds possible over northern Johnson County. .SPOTTER INFORMATION STATEMENT... Weather spotters are encouraged to report significant weather conditions according to standard operating procedures.
The national radar mosaic for the moment the first event began.
1 high wind, 1 winter storm. Local standard time, as filed.
There were several hours of high winds in Natrona County. Some of the maximum wind gusts included 76 mph on the south side of Casper and 62 mph at the Natrona County airport.
Heavy snow fell in portions of the Tetons. The highest amount measured was 16 inches at the Jackson Hole Ski Resort.
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: 863102, 863107.