A feed of Pacific moisture moved into western Wyoming and brought locally heavy snow to western Wyoming. The heaviest snow fell in Teton and Salt Mountains where 16 inches of snow was measured at Jackson Hole and Commissary Ridge respectively.
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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 feed of Pacific moisture moved into western Wyoming and brought locally heavy snow to western Wyoming. The heaviest snow fell in Teton and Salt Mountains where 16 inches of snow was measured at Jackson Hole and Commissary Ridge respectively. In the lower elevations, the highest amount was measured at Alpine where 12 inches of new snow fell.
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 12, 4:52 AM MST, 8 minutes earlier.
Area Forecast Discussion National Weather Service Riverton WY 452 AM MST Thu Dec 12 2019 .SHORT TERM...(Today through Friday) Issued at 115 AM MST Thu Dec 12 2019 Very moist westerly flow is now pushing into western Wyoming as expected. Light snow with some fog will continue for the rest of the night and precipitation will pick up in intensity after sunrise. With the surface pressure gradient increasing across the state, winds will be increasing with time as well, particularly in the mountains and from southwest into central WY. Precipitation will largely stay confined to the western mountains and valleys through the day, though some light to moderate snow should move into the Upper Green River Basin to South Pass and Sweetwater County late this afternoon as the first wave of the series moves from the Great Basin to the Central Rockies. Accumulations in the western valleys could be variable this afternoon as temperatures are likely to rise slightly to the low to mid 30s. this strong westerly flow pattern will mainly keep areas east of the divide free of precipitation, though some blow over will bring snow showers to higher elevations on the east slopes of the Absarokas and Wind Rivers. The combination of moderate to heavy snow with breezy to windy conditions will create hazardous road conditions in some areas, especially mountain passes such as Teton and Togwotee and perhaps from Moose to Moran. The moist westerly flow will continue Thursday night into Friday morning as another wave in the flow moves into the forecast area. Moderate to strong wind will continue through the night as well as another surface low moves from Montana into the northern Plains and a mid-level disturbance moves through southwest WY. The NAM is suggesting strong wind gusts from Big Piney to South Pass to Sweetwater County from Friday midnight to 10am with 700mb NW winds of 50 kts. A weak boundary moving south from Montana after this low center should help bring some light precipitation to northern and central WY during the day Friday, while snow slowly decreases across the west by Friday evening. This second wave looks to bring in somewhat colder air with 700mb temps decreasing by 2-4 C, so snow should be more constant through the day on Friday. Previewing the long term, another wave will increase precipitation across southwest and southern WY Friday night into early Saturday. .LONG TERM...(Friday night through Wednesday) Issued at 251 AM MST Thu Dec 12 2019 As mentioned, another round of snow moves in Friday night impacting southern to western WY. Breezy winds will stick around during the night and blowing snow will be likely. Showers will stick around on Saturday, but become lighter and decrease later in the day. By Saturday night, light isolated shower remain over the west, but otherwise there will be dry conditions over the rest of the CWA. Temperatures will also be dropping Saturday night with most Sunday morning lows in the single digits to negatives. Sunday will be much colder and dry across the area, with again, just slight PoPs over the western mountains. Below normal temperatures will continue into the work week with widespread highs in the teens to twenties through Tuesday. && .AVIATION...(For the 12Z TAFS through 12Z Friday morning) Issued at 450 AM MST Thu Dec 12 2019 West of the Continental Divide...KBPI/KJAC/KPNA/KRKS Terminals Snow will occur in the west today and tonight with MVFR to IFR conditions occurring. KJAC will be most impacted. Local LIFR conditions are possible. will also have a gusty wind. Some rain or snow showers will occur at times in southern WY after 21Z with local MVFR conditions. Mountains will be frequently obscured in the west through the period. Please see individual terminal forecasts for more details. East of the Continental Divide...KCOD/KCPR/KLND/KRIW/KWRL Terminals VFR conditions are forecast at the terminals through the period. A gusty wind will be common at the KCPR airport through most of the period. Some snow will occur in the Bighorn mountains after 21Z through 12Z Friday. Expect mountain top obscuration along with MVFR conditions in the vicinity of the mountains. 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 1251 AM MST Thu Dec 12 2019 Moist westerly flow is now moving into western Wyoming. Light snow will increase to moderate to heavy during the day across the western part of the state. A moderate pressure gradient over the state will continue breezy to windy conditions as well. The first wave will bring the heavier precipitation today, with a second wave overnight. And third wave will move through southwest Wyoming Friday night into Saturday morning. Southwest WY will see light snow at times, and a boundary moving south from Montana should generate some light snow from northern into central WY Friday morning. Winds will be strongest in the higher elevations and from Sweetwater county into Natrona county through the next 48 hours, with sustained 15 to 25 mph and gusts 25 to 40 mph. Areas along the east slopes of the Absarokas and Wind Rivers may see some blow over snow showers at times, but also some clearing with gusty winds around 40 mph. Saturday and Sunday will remain cold with lingering showers. && .RIW WATCHES/WARNINGS/ADVISORIES... Winter Storm Warning until 5 PM MST Friday for WYZ001-002-012- 014-024. Winter Weather Advisory until 5 PM MST Friday for WYZ013-023-025- 027. && SHORT TERM...McDonald LONG TERM...Bourque AVIATION...Ross/Bourque FIRE WEATHER...McDonald
Hazardous Weather Outlook National Weather Service Riverton WY 300 AM MST Thu Dec 12 2019 WYZ001>020-022>030-131200- 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- 300 AM MST Thu Dec 12 2019 ...WINTER STORM WARNING AND WINTER WEATHER ADVISORIES IN EFFECT FROM 5 AM THURSDAY TO 5 PM MST FRIDAY FOR MUCH OF WESTERN WYOMING... This Hazardous Weather Outlook is for Western and Central Wyoming. .DAY ONE...Today and Tonight. Moderate to heavy snow will fall in the mountains of western Wyoming. Snow accumulations are likely to be between 10 and 20 inches by Friday. Accumulating snow will fall in the valleys with significant accumulations possible Thursday night. The snow will be accompanied by increasing wind late Thursday and early Friday. Gusty west to southwest wind is expected across central Wyoming and the eastern mountain foothills. South Pass into Sweetwater county could see strong northwest wind Thursday night into Friday morning. .DAYS TWO THROUGH SEVEN...Friday through Wednesday. Friday and Saturday...Light to moderate snow will continue in the western mountains and valleys. A weak cold front slipping south to the east of the Continental Divide could produce light snow across the northern basins and into Johnson and Natrona counties on Friday and again on Saturday. Southwest Wyoming will see another round of snow Friday night into Saturday morning. .SPOTTER INFORMATION STATEMENT... Weather spotters are encourage to report snowfall totals, high wind gusts, and hazardous weather impacts. McDonald
The national radar mosaic for the moment the first event began.
5 winter storm. Local standard time, as filed.
Heavy snow fell in portions of the Tetons. Some of the heaviest amounts included 16 inches at the Jackson Hole Ski resort and 14 inches at Grand Targhee.
Heavy snow fell in portions of the Salt and Wyoming Mountains. The highest amount was 16 inches at Commissary Ridge.
Locally heavy snow occurred in southwestern portions of Yellowstone Park. The highest amount was 14 inches at the Lewis Lake Divide.
In Alpine, 12 inches of new snow fell. Amounts dropped substantially further south with only 4 inches at Afton.
A COOP observer reported 8 inches of snow at DuBois. Amounts dropped sharply further to the south and east.
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: 868604, 868605, 868606, 868607, 868608.