A compact low pressure area passed across southern Wyoming. Star Valley received 6 to 8 inches of snow.
Every event with a place to put it; 3 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 compact low pressure area passed across southern Wyoming. Star Valley received 6 to 8 inches of snow. A heavy snow band also developed over Fremont County and brought locally heavy snow. Around Riverton, anywhere from 4 to 7 inches of new snow fell. Similar amounts fell around the Lander Foothills.
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, 8:45 PM MST, 15 minutes earlier.
Area Forecast Discussion National Weather Service Riverton WY 845 PM MST Tue Jan 10 2023 .UPDATE... Issued at 838 PM MST Tue Jan 10 2023 Models show a mesoscale low developing in the Wind River Basin toward 5 AM. Some snow is expected ahead of this feature mainly after 2 AM with the possibility of increased snowfall rates between 6 AM and 9 AM. The latest high resolution models have trended with more snowfall across the Wind River Basin and Lander Foothills with 2 to 4 inches with possibly higher amounts. Thus have expanded the winter weather advisory into the Wind River Basin and Lander Foothills. The timing (11 PM Tuesday to 11 AM Wednesday) will match the ongoing winter weather advisory east of this area. Concerned a bit that there could be accumulating snow could linger through mid-afternoon, but impacts on roads will lessen as the afternoon progresses as temps warm. Would expect road conditions go from slushy to snowpacked in the morning to more wet as the afternoon progresses. && .SHORT TERM...(Today through Wednesday) Issued at 247 PM MST Tue Jan 10 2023 Sky cover diminished and conditions dried out late Tuesday morning and early afternoon following the departure of our first round of snow. Lower clouds and light precipitation have lingered in Natrona County early Tuesday afternoon, but conditions should briefly improve before the next storm arrives late Tuesday evening. KMTX radar already showing precipitation returns over northern Utah heading toward western Lincoln County prior to sunset. The overall trend will be for moisture to overspread western and southern Wyoming prior to midnight before quickly enveloping central Wyoming early Wednesday morning. The western mountains and valleys have a period of moderate snow from about midnight to 7AM Tuesday during what should be a more favorable period of orographics and deeper moisture. Temperatures at 700mb remain relatively warm, so instability will be limited to support heavier snow. For now, went with a forecast slightly below advisory thresholds for the west. Temperatures are mild tonight given the increasing cloud cover. Early Wednesday morning finds a mid-level circulation forming over Fremont and Natrona counties between 06Z-12Z. Dynamic lift associated with this feature should enhance snowfall around sunrise for these areas. Cyclonic rotation around the circulation lifts a band of heavier snow north into southern portions of the Bighorn Basin and Johnson County prior to sunrise and into the morning hours. As the circulation tracks east, the snowfall will slowly taper over the west through the morning, with mainly light mountain accumulations for the afternoon. Northwest flow on the backside of the circulation should shift the snow back to the south and east during the afternoon, lingering longest over Natrona County. However, with surface temperatures rising to around 30F additional accumulations will be limited during the afternoon hours over the lower elevations. Westerly downsloping flow over the southern-third of the forecast area should dry conditions Wednesday morning. This comes with a cost, however, as west wind rapidly picks up during the morning. Expect widespread 25 to 40 mph wind along I-80 and US 30 through Sweetwater and south Lincoln counties through the day. The interior snow-covered basins see improved mixing Wednesday, so temperatures may be the warmest of the week. Most other areas will be a tad below seasonal normals. Light snow may hold on until shortly after sunset Wednesday around Casper. Otherwise, drier conditions and decreasing cloud cover arrive for most areas Wednesday evening as the moisture shifts east. Though lacking a cold push from the north, low temperatures and the prospect of fog will need to be monitored Wednesday night. Fresh snow cover and a clearing sky could set the stage from colder lows and the development of patchy fog in the basins. .LONG TERM...(Thursday through Tuesday) Issued at 247 PM MST Tue Jan 10 2023 A strong, sharp ridge will build into the area Thursday bringing dry weather to the region through Saturday. There will be gusty winds again Thursday afternoon along the mountains and from South Pass to Fremont and southern Johnson counties. The weather will be pretty quiet through late Saturday, and then a new trough will begin a push into the west. This will bring the next round of accumulating snow late Saturday through Monday for western mountains and valleys. Temperatures will be closer to normal values for the latter part of the forecast period. Temperatures in the Wind River and Green River basins could again decide to stay on the low side with the heavy snowpack in those areas. Saturday through Monday will see the gusty afternoon winds in the usual prone locations. The snow with this next system is expected to remain mainly across the west and south. && .AVIATION...(For the 00Z TAFS through 00Z Wednesday evening) Issued at 453 PM MST Tue Jan 10 2023 West of the Divide...KBPI/KJAC/KPNA/KRKS Terminals. The next round of moisture, subsequent light snow, and IFR/MVFR conditions arrives Tuesday evening from the southwest. The snow and low clouds spread north and the snow returns between 02Z and 05Z/Wednesday. Expect these conditions to persist through around 12Z/Wednesday, with very slow improvement through the remainder of Wednesday morning. While MVFR persists until around midday Wednesday, the snow does decrease in intensity. The west-northwest flow aloft may very likely keep light snow and MVFR at KJAC through the period, while the other terminals improve to low-end VFR. Mountains frequently obscured after 00Z/Wednesday. East of the Divide...KCOD/KCPR/KLND/KRIW/KWRL Terminals. Moisture returns to central Wyoming from the southwest late Tuesday evening. Beginning around 06Z/Wednesday, light snow and IFR/MVFR conditions develop in association with a mid-level circulation that forms in central Wyoming early Wednesday morning. Dynamics associated with this circulation will provide for a more intense period of snow between 09Z-15Z/Wednesday. Localized LIFR possible in the central terminals during this time and even through 18Z/Wednesday at KCPR. To the north, the snow holds off until closer to 12Z/Wednesday with MVFR through the morning. The circulation makes its way slowly east with decreasing snow and slowly improving conditions from northwest to southeast late in the day. Mountains frequently obscured after 05Z/Wednesday. 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 247 PM MST Tue Jan 10 2023 After a quick break, the snow returns from the southwest overnight and spreads light snow across the southern two-thirds of the forecast area. The heaviest snow falls late tonight and Wednesday morning with 2 to 4 inch totals widespread in the lower elevations of central and southern Wyoming. The snow makes its way slowly north through midday Wednesday with additional accumulation in southern portions of the Bighorn Basin and Johnson County. A circulation in the mid-levels of the atmosphere slowly exits east late in the day allowing for the snow to diminish from west-to-east. As for wind, a post-frontal westerly wind gusting 30 to 40 mph will be found across Sweetwater County and adjacent areas of Sublette and Lincoln counties through the day Wednesday. Northern and central areas of the state can expect a north wind 10 to 20 mph Wednesday afternoon with mainly dry conditions. Despite the wind, low mixing heights keep smoke dispersal in the fair category in the windy locations with poor dispersal elsewhere. Looking ahead to Thursday and Friday, a ridge of high pressure builds into the state from the west effectively shutting off any precipitation through Friday night. Temperatures are to be seasonal to slightly above in snow-free areas with below normal temperatures in the snow-covered basins. && .RIW WATCHES/WARNINGS/ADVISORIES... Winter Weather Advisory until 11 AM MST Wednesday for WYZ011-017- 018-020-022. && UPDATE...Murrell SHORT TERM...CNJ LONG TERM...Swanson AVIATION...CNJ FIRE WEATHER...CNJ
Hazardous Weather Outlook National Weather Service Riverton WY 848 PM MST Tue Jan 10 2023 WYZ001>020-022>030-111300- 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- 848 PM MST Tue Jan 10 2023 ...Winter Weather Advisory for Natrona, southern Johnson County and the Wind River Basin late tonight into Wednesday morning... This Hazardous Weather Outlook is for Western and Central Wyoming. .DAY ONE...Tonight. Light to occasional moderate snow spreading from southwest and west to central areas tonight. Please see the winter weather advisory and special weather statement for more details. .DAYS TWO THROUGH SEVEN...Wednesday through Monday. Wednesday...Snow decreases from west to east. Areas of blowing snow in Sweetwater County. .SPOTTER INFORMATION STATEMENT... Spotter activation will not be needed at this time. TEAM RIVERTON/21
Special Weather Statement National Weather Service Riverton WY 350 PM MST Tue Jan 10 2023 WYZ001-111300- Yellowstone National Park- Including the cities of Lake, Mammoth, and Old Faithful 350 PM MST Tue Jan 10 2023 ...Another Round of Snow Tonight and Wednesday... This is a special weather statement from the National Weather Service Office in Riverton. * WHAT...Light to moderate snowfall. Total snowfall of 3 to 6 inches. * WHERE...Yellowstone National Park. * WHEN...Tonight and Wednesday. The heaviest snow will occur late tonight into Wednesday morning. * ADDITIONAL DETAILS...Mammoth to the Northeast Entrance of Yellowstone might only receive 1 to 2 inches. WYZ012-014-024-111300- Teton and Gros Ventre Mountains-Wind River Mountains West- Salt River and Wyoming Ranges- 350 PM MST Tue Jan 10 2023 ...Another Round of Snow Tonight and Wednesday... This is a special weather statement from the National Weather Service Office in Riverton. * WHAT...Light to moderate snowfall. Total snowfall between 4 and 8 inches. * WHERE...Teton and Gros Ventre, Western Wind River, and the Salt and Wyoming Mountains. * WHEN...Tonight and Wednesday. The heaviest snowfall will likely occur between 10 PM tonight and 10 AM Wednesday. * ADDITIONAL DETAILS...The Teton Mountains could receive 12 to 14 inches on the higher peaks. Please monitor the Bridger-Teton Avalanche Center at bridgertetonavalanchecenter.org, if your plans include travel into the backcountry. WYZ013-023-111300- Jackson Hole-Star Valley- Including the cities of Jackson, Afton, Alpine, Star Valley Ranch, and Thayne 350 PM MST Tue Jan 10 2023 ...Another Round of Snow Tonight and Wednesday... This is a special weather statement from the National Weather Service Office in Riverton. * WHAT...Light to briefly moderate snow. Total snowfall between 1 and 3 inches. * WHERE...Jackson Hole and Star Valley. * WHEN...Tonight and Wednesday. The heaviest snowfall will likely occur between 10 PM tonight and 10 AM Wednesday. * ADDITIONAL DETAILS...Please monitor the Bridger-Teton Avalanche Center at bridgertetonavalanchecenter.org, if your plans include travel into the backcountry. WYZ025>027-111300- Upper Green River Basin Foothills-Upper Green River Basin- South Lincoln County- Including the cities of Pinedale, La Barge, Big Piney, Farson, Kemmerer, and Cokeville 350 PM MST Tue Jan 10 2023 ...Another Round of Snow Tonight and Wednesday... This is a special weather statement from the National Weather Service Office in Riverton. * WHAT...Light to briefly moderate snow. Total snowfall between 2 and 4 inches. * WHERE...The Upper Green River Basin, and southern Lincoln County. * WHEN...Tonight and Wednesday morning. The heaviest snow is expected between 8 PM tonight and 4 AM Wednesday. * ADDITIONAL DETAILS...The bulk of the snow will end between 4 AM and 9 AM Wednesday. WYZ028>030-111300- Rock Springs and Green River-Flaming Gorge-East Sweetwater County- Including the cities of Rock Springs, Green River, and Wamsutter 350 PM MST Tue Jan 10 2023 ...Another Round of Snow Tonight and Wednesday Morning... This is a special weather statement from the National Weather Service Office in Riverton. * WHAT...Light snow. Total snowfall of 1 to 2 inches with isolated amounts of 3 inches. * WHERE...Sweetwater County. * WHEN...Tonight and Wednesday morning. The heaviest snow will likely occur between 10 PM tonight and 6 AM Wednesday, ending around noon Wednesday. * ADDITIONAL DETAILS...There could be areas of blowing snow Wednesday morning as westerly winds increase. WYZ015-018-019-111300- Wind River Mountains East-Lander Foothills- Green Mountains and Rattlesnake Range- Including the cities of Lander and Jeffrey City 350 PM MST Tue Jan 10 2023 ...A Round of Snow Late Tonight and Wednesday... This is a special weather statement from the National Weather Service Office in Riverton. * WHAT...Light to briefly moderate snow. Total snowfall of 2 to 3 inches in the lower elevations, and 3 to 6 inches in the mountains. * WHERE...Lander Foothills, the eastern Wind River Mountains, and the Green Mountains and Rattlesnake Range. * WHEN...Late tonight and Wednesday. * ADDITIONAL DETAILS...Isolated amounts between 3 and 6 inches of snow are possible northwest of Lander towards and into Sinks Canyon. WYZ017-111300- Wind River Basin- Including the cities of Riverton and Shoshoni 350 PM MST Tue Jan 10 2023 ...A Round of Snow Late Tonight and Wednesday... This is a special weather statement from the National Weather Service Office in Riverton. * WHAT...Light to briefly moderate snowfall. Total snowfall between 1 and 3 inches. * WHERE...Wind River Basin. * WHEN...Late tonight and Wednesday. WYZ005-007-111300- Southwest Big Horn Basin-Owl Creek and Bridger Mountains- Including the city of Thermopolis 350 PM MST Tue Jan 10 2023 ...A Round of Snow Late Tonight and Wednesday... This is a special weather statement from the National Weather Service Office in Riverton. * WHAT...Light to briefly moderate snow. Total snowfall between 1 and 3 inches in the lower elevations, and 3 to 6 inches in the mountains. * WHERE...Southwest Bighorn Basin including Thermopolis, and the Owl Creek and Bridger Mountains including the Wind River Canyon. * WHEN...Late tonight and Wednesday. 21
PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE RIVERTON WY
708 PM MST TUE JAN 10 2023
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0650 PM NON-TSTM WND GST 2 NE MILLS 42.87N 106.34W
01/09/2023 M62 MPH NATRONA WY MESONET
MILLS 2 NE (WYDOT). JUNCTION OF INTERSTATE
25 AND US 87.
0932 PM NON-TSTM WND GST 2 SSE CASPER 42.81N 106.31W
01/09/2023 M78 MPH NATRONA WY MESONET
CASPER 2.1 SW (WYDOT). OUTER DRIVE ON THE
SOUTH SIDE OF CASPER.
1126 PM NON-TSTM WND GST 4 SE EVANSVILLE 42.84N 106.20W
01/09/2023 M63 MPH NATRONA WY MESONET
INTERSTATE 25 AT HAT SIX ROAD (WYDOT).
&&Special Weather Statement National Weather Service Riverton WY 838 PM MST Tue Jan 10 2023 WYZ017-018-110445- Wind River Basin-Lander Foothills- Including the cities of Riverton, Shoshoni, and Lander 838 PM MST Tue Jan 10 2023 A winter weather advisory has been issued for the Wind River Basin including the Lander Foothills, from 11 PM Tuesday through 11 AM Wednesday. Please see the winter weather advisory for more details. 21
The national radar mosaic for the moment the first event began.
3 winter storm. Local standard time, as filed.
Multiple snowfall reports of 6 to 8 inches across Star Valley, including in Afton, Bedford, Thayne, and Alpine.
A storm total snowfall of 7.1 inches occurred at the Riverton Weather Forecast Office.
Trained spotters reported 5 to 7 inches of new snow around Lander.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Wyoming in 2023Every state in 2023This day in weather historyWarnings in Wyoming, January 2023
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: 1078766, 1076714, 1076715.