A persistent moist west to northwesterly flow brought heavy snow to portions of the western mountains. The heaviest fell at the Jackson Hole Ski Resort were 28 inches of new snow fell.
Every event with a place to put it; 2 filed by county or forecast zone are drawn at its center, in a lighter ring. Tap one for its entry below.
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 persistent moist west to northwesterly flow brought heavy snow to portions of the western mountains. The heaviest fell at the Jackson Hole Ski Resort were 28 inches of new snow fell. Amounts dropped sharply at lower elevations and other SNOTEL sites. In the Salt and Wyoming Range, 21 inches was measured at Commissary Ridge. Like in the Tetons, other areas saw much less snow.
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, 1:18 PM MST, 42 minutes earlier.
Area Forecast Discussion National Weather Service Riverton WY 118 PM MST Wed Jan 8 2020 .SHORT TERM...This afternoon through Thursday night Not much change in the forecast this morning. A cold front was entering western WY around daybreak this morning, with a band of snow moving ahead of it. Snow was already ending over far western portions by 9am, as the front continues its eastward progression. This band of snow is expected to move over southwestern and southern portions later this morning into the afternoon, however, snowfall amounts are expected to remain minimal. Gusty winds also continue over the Wind Corridor, from Red Canyon to Casper. These winds are expected to decrease this afternoon, once the cold front moves through these areas. Winds will turn to the west-northwest, which is a less-conducive direction for strong winds. Winds will continue to be gusty in the wake of this front through Thursday morning, but not nearly as strong. A broad trough will be in place over the Cowboy State Thursday, with orographic flow keeping snow going over far western portions (mainly in the mountains). Light snow will continue Thursday afternoon into Thursday night. Another cold front will move across the area Thursday night. This could produce very light snow/flurries to areas east of the Divide (mainly northern portions), as it moves through the area. This front will end the snow over the west, as the upper level flow turns northwesterly. Additional accumulations of 2 to 3 inches are expected in the western mountains Thursday night, with up to 1 inch in the valleys. Thus, will likely not extend the advisory to coincide with the cold front passage and the end of the snow. .LONG TERM...Saturday through Wednesday Aside from a few lingering snow showers in the morning, Friday looks to be fairly uneventful. Induced ridging will move in behind the exiting trough Friday afternoon but this ridge will not last long. The approach of the next system will lead to some strong winds in the Absaroka Mountains, which currently do not look like they will mix down to the Cody Foothills but will need to be watched. An upper low/trough on the far western Aleutian Islands of Alaska will impact the Cowboy State Saturday. Widespread snow will be ongoing over western Wyoming Saturday morning. The snow is expected to shift southeast across the southern portions of the forecast area from the combination of a cold front and the dynamics with the left-front quad of an upper jet. Models show the overall intensity of snow decreasing Saturday afternoon. Areas east of the Divide look to mainly dry Saturday from downsloping, with chances of snow generally confined to the Johnson County area. Also expect some strong wind impacting the wind corridor from Rock Springs and Casper. Saturday night and Sunday, snow will continue out west from a combination of an overall moist orographic flow, shortwaves in the flow and the possibility of some jet streak dynamics. Areas east of the Divide look to be mainly dry. By 00Z Monday models, now including the GFS, show the initial shot of bitterly cold along the Montana/Wyoming border. Sunday night and Monday, a significant shortwave trough is expected to pull east southeast across the Rockies with decent lift associated with the left-exit region of a strong upper jet. This will likely bring another round of significant snowfall over the west. There could be some snow spilling east of the Divide on Monday, but chances remain slim. The Arctic cold front should push south, east of the Divide Monday into Monday night. Another trough is progged to push across the Rockies Tuesday and Wednesday with another round of potentially significant snow across the west on Tuesday. This trough has the best chance of snow occurring east of the Divide Tuesday night as there looks to be isentropic lift over the Arctic air which will be in place by the time the trough pulls across the area. Bitter cold temperatures are still expected Tuesday night and Wednesday. Models have warmed a little bit at 700mb from last night but not by much, still hovering around -20 in the north. Many areas will remain in the single digits for a high on Wednesday. && .AVIATION...For the 18Z TAFS through 18Z Thursday East of the Divide...KCOD/KCPR/KLND/KRIW/KWRL Terminals VFR conditions will occur at the terminal sites today and tonight. A gusty wind at KCPR airport will continue until 00Z, then decrease. A weather system will move through the area this afternoon and evening. Isolated snow showers will be possible at the lower elevations but are not expected to impact any terminals. Snow showers are expected over most of the mountains with lower ceilings and some mountain obscuration. West of the Divide...KBPI/KJAC/KPNA/KRKS Terminals Expect snow in the mountains today and tonight with very low ceilings and frequent mountain obscuration. KJAC will see snow most of the period with MVFR to IFR conditions. KPNA and KBPI will see some snow at times today. MVFR conditions will prevail through tonight at KBPI and is likely at KPNA around 04Z Thursday. KRKS will see VFR conditions through the period with a gusty wind from 21Z until 04Z. Isolated snow showers will occur in southern WY this afternoon and could get close to KRKS airport until 00Z. Please see the Aviation Weather Center and/or CWSU ZDV and ZLC for the latest information on icing and turbulence forecasts. && .FIRE WEATHER... Periods of snow will continue across much of western Wyoming today through Thursday. Expect mainly dry conditions east of the Divide. Windy conditions will continue this afternoon, from Red Canyon through Casper, before finally subsiding this evening. Relative humidity will remain above critical levels. Mixing and smoke dispersal will range from poor east of the Divide to fair across the western mountains. && .RIW WATCHES/WARNINGS/ADVISORIES... Winter Weather Advisory until 6 PM MST Thursday for WYZ001-012- 013-023-024. && SHORT TERM...LaVoie LONG TERM...Hulme AVIATION...Hulme FIRE WEATHER...Hattings/LaVoie
Hazardous Weather Outlook National Weather Service Riverton WY 352 AM MST Wed Jan 8 2020 WYZ001>020-022>030-091330- 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- 352 AM MST Wed Jan 8 2020 ...Winter Weather Advisory for much of Western Wyoming through Thursday Morning... This Hazardous Weather Outlook is for Western and Central Wyoming. .DAY ONE...Today and Tonight. Significant snow fall likely over the far west. Please see Winter Weather Advisory and forecasts for details. Strong winds possible from the Red Desert through Casper today. .DAYS TWO THROUGH SEVEN...Thursday through Tuesday. Thursday...Snowfall continuing in the west. Please see Winter Weather Advisory and forecasts for details. Saturday through Tuesday...Significant snowfall probable over the west. Very windy on Saturday between Rock Springs and Casper. Bitterly cold temperatures Tuesday and beyond next week. The coldest area will be over the east and north, where record low temperatures and coldest highs are possible. .SPOTTER INFORMATION STATEMENT... Weather spotters are encourage to report snowfall amounts. Team Riverton
Special Weather Statement National Weather Service Riverton WY 1011 AM MST Wed Jan 8 2020 WYZ019-020-090000- Green Mountains and Rattlesnake Range- Natrona County Lower Elevations- Including the cities of Jeffrey City and Casper 1011 AM MST Wed Jan 8 2020 ...Strong Gusty winds continue today... This is a special weather statement from the National Weather Service Office in Riverton. * WHAT...Southwest winds 25 to 35 mph with gusts to 50 to 55 mph. Occasional gusts of 55 to 60 mph are possible in favored areas like Wyoming Boulevard south of Casper. * WHERE...Along the Highway 287 corridor from Beaver Rim to Jeffrey City and along the Highway 220 corridor, from Alcova to Casper and Wyoming Boulevard south of Casper. * WHEN...Through 6 pm today. * ADDITIONAL DETAILS...Anyone traveling along Highway 20/26, 220, 287 and Interstate 25 on Tuesday should anticipate sudden strong cross winds.
The national radar mosaic for the moment the first event began.
2 winter storm. Local standard time, as filed.
Heavy snow fell at the Jackson Hole Ski Resort where 28 inches of new snow fell. Other locations saw at the most 14 inches with most areas less than 12 inches.
At Commissary Ridge, 21 inches of new snow fell. Much less snow fell at the other sites with most under 12 inches.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Wyoming in 2020Every state in 2020This day in weather historyWarnings in Wyoming, January 2020
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: 868874, 868875.