Another shortwave moved through western Wyoming and brought heavy snow to portions of the area. The heaviest snow fell in the favored upslope areas of the Tetons where 22 inches was recorded at Grand Targhee.
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.
Another shortwave moved through western Wyoming and brought heavy snow to portions of the area. The heaviest snow fell in the favored upslope areas of the Tetons where 22 inches was recorded at Grand Targhee. In the Star Valley, favorable northwest flow brought 13 inches of snow at Alpine. Snow amounts dropped sharply further south with only 2 inches at Afton, Wyoming.
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 10, 10:20 PM MST, 1 hour 40 minutes earlier.
Area Forecast Discussion National Weather Service Riverton WY 1020 PM MST Fri Jan 10 2020 .SHORT TERM...This evening through Saturday night Dry conditions will continue across the area this afternoon into the evening. Gusty west winds over Sweetwater County will transition toward Casper this evening, as the surface gradient tightens in response to the approaching storm system. These winds tonight will continue to increase from Red Canyon/South Pass over to Natrona County and southern Johnson County. Gusts of 35 to 45 mph will occur from tonight through the day Saturday. This winter storm will bring the next round of snow to northwestern portions tonight, spreading southward across the west through the overnight hours. Snow will be ongoing Saturday and Saturday night. Periods of heavier snow will be possible over the Tetons and Jackson Valley Saturday afternoon and evening. Have issued Winter Weather Advisories for portions of the far west for this storm. These advisories will likely be extended into Sunday, as snow is expected to continue. More details on this will be explained below. Otherwise, very light snow/flurries will spread across southern portions by Saturday morning. These showers will continue through the day, before ending by Saturday evening. Gusty winds will return by the afternoon, which could cause blowing snow/reduced visibilities over the Interstate 80 corridor. Dry and cold conditions will remain in place across areas east of the Divide Saturday. Portions of Johnson County and the Cody Foothills will be the exceptions, where highs in the middle 30s are expected. .LONG TERM...Sunday through Friday Snow does indeed continue on Sunday across the west. Winds will be breezy in some areas west and gusty in the mountains and prone areas east of the Divide. Some isolated snow may make it to the Bighorns or across the far south, but snow east of the Divide will be more likely on Monday. In fact, Monday could be quite nasty across the far south with gusty winds developing and scattered snow likely in the afternoon hours. Tuesday afternoon looks to be a repeat with snow still steadily falling in the west and scattered PoPs across the south. Winds on Tuesday will not be quite as strong as on Monday, but still blustery and blowing snow quite likely. Wednesday through Friday, snow finally lets up in the west, but unfortunately will not stop altogether. A trough will be moving onto the west coast and near the area keeping moisture and snow chances across the west. The GFS is leaning towards periods without snow, but pinpointing the timing down is too uncertain this far out. Aside from the ongoing train of snow for western WY, also of note is temperatures. Previous model runs had arctic air moving in over the area, but have since backed off on the severity of said cold. The coldest day will be Wednesday, with widespread negative lows still likely even with the slightly warmer trend. && .AVIATION...(For the 06Z TAFS through 06Z Sunday) Issued at 1015 PM MST Fri Jan 10 2020 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 will decrease around 01Z. Snow will occur over the Wind River and Absaroka mountains with lower ceilings and some mountain obscuration. West of the Divide...KBPI/KJAC/KPNA/KRKS Terminals Snow will occur in the mountains overnight through Saturday night with MVFR to IFR conditions. Mountains will be frequently obscured. KJAC will see snow for most of the forecast period with MVFR/IFR conditions. KPNA and KBPI airports will see a period of snow Saturday morning with MVFR to IFR conditions, then improving conditions after 19Z. VFR conditions will occur by 00Z. KRKS will see some light snow pass through Saturday morning with MVFR to IFR conditions. After 18Z, VFR conditions are expected. The gusty wind will occur through 01Z, then decrease. Please see the Aviation Weather Center and/or CWSU ZDV and ZLC for the latest information on icing and turbulence forecasts. && .FIRE WEATHER... Dry conditions will continue across the area through this evening, before snow returns to far western portions by midnight. Snow will spread southward through the overnight hours and continue through the day Saturday. Snow will remain likely over these areas through Tuesday night. Gusty winds over zone 279 this afternoon will subside this evening and shift toward zones 280/289. These winds will increase with gusts of 35 to 45 mph late tonight and continue through the day Saturday. Otherwise, temperatures will remain cold tonight and Saturday. Zones 276 and 281 will warm above freezing during the day Saturday. && .RIW WATCHES/WARNINGS/ADVISORIES... Winter Weather Advisory from 5 AM Saturday to 6 AM MST Sunday for WYZ023-024. Winter Weather Advisory from 11 PM this evening to 6 AM MST Sunday for WYZ012-013. && SHORT TERM...LaVoie LONG TERM...Bourque AVIATION...AR FIRE WEATHER...LaVoie
Hazardous Weather Outlook National Weather Service Riverton WY 233 PM MST Fri Jan 10 2020 WYZ001>020-022>030-112145- 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- 233 PM MST Fri Jan 10 2020 ...Winter Weather Advisory for portions of Western Wyoming late tonight through Sunday Morning... This Hazardous Weather Outlook is for Western and Central Wyoming. .DAY ONE...Tonight. Snow will return to far western portions tonight, continuing into Saturday morning. .DAYS TWO THROUGH SEVEN...Saturday through Thursday. Saturday...Light snow to flurries, combined with gusty winds, will create periods of blowing snow across southern portions. Saturday through Tuesday...Significant snowfall possible 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 encouraged today to report significant weather conditions, according to standard operating procedures. Team Riverton
The national radar mosaic for the moment the first event began.
2 winter storm. Local standard time, as filed.
Heavy snow fell through much of the Tetons. The highest amount was 22 inches at the Grand Targhee SNOTEL site.
Heavy snow fell in the northern portion of the Star Valley where 13 inches of snow fell at Alpine, Wyoming. Amounts dropped sharply further to the south.
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: 868878, 868882.