A slow-moving weather system brought heavy snow, with emphasis on the northern half of the state. The heaviest snow fell in the Tetons, with over 2 feet in some locations.
Every event with a place to put it; 8 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 slow-moving weather system brought heavy snow, with emphasis on the northern half of the state. The heaviest snow fell in the Tetons, with over 2 feet in some locations. In the lower elevations, the heaviest snow fell across Park County, with many seeing amounts over 6 inches, with up to 19 inches near Cody. Many roads were closed across northern Wyoming during the storm.
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 Mar 24, 4:14 AM MST, 4 hours 46 minutes earlier.
Area Forecast Discussion National Weather Service Riverton WY 514 AM MDT Fri Mar 24 2023 .SYNOPSIS... Issued at 303 AM MDT Fri Mar 24 2023 No change in the forecasted pattern for a little over a week. A very active Spring (more like Winter) weather pattern will be in place through the next week. There will be chances for precip (mostly snow) across the area and consistent snow for western WY. Where new snow falls the sun should melt it in a couple of days thanks to the late March sun angle, but where stubborn snowpack still exists melting will be slow. This will limit how much temperatures can warm even on the clear days. Temperatures will remain below normal across the CWA for the foreseeable future. The active weather pattern will result in elevated wind for much of the area, especially wind prone areas. && .DISCUSSION...(Today through Thursday) Issued at 303 AM MDT Fri Mar 24 2023 Winter continues over the next week thanks to a parade of upper lows expected to pass through the region. The CWA will remain in a mostly zonal westerly flow this morning before the next upper low drops in from the PACNW this afternoon. This westerly flow will keep weak moist upslope going in western WY and light snow will continue there, especially in western mountains. This afternoon through about Monday afternoon will feature several upper lows with vort maxes that will result in the formation of a sfc low in central/eastern WY. With the complexity of multiple upper lows comes uncertainty in where heavy snow bands will set up, which will lead to enhanced snowfall totals for certain areas. With this in mind there could be significant forecast changes in the coming days when it comes to snowfall totals. Confidence is increasing on northern portions of the area receiving moderate to substantial snow amounts, mainly from this afternoon through Saturday night. The initial upper low is likely to move into southern WY and become nearly stationary during that time, which would put the best CVA over the northern portions of the area, especially the Bighorn Basin. There likely won't be much jet support, so lift will be in the form of CVA, easterly moist upslope, and decent to moderate isentropic lift. Moisture values appear sufficient, but not spectacular with PWAT values of 0.25" to 0.35". Will be upgrading the Winter Storm Watches to Warnings for the Absaroka Mountains, Owl Creek and Bridger Mountains, and the Bighorn Mountains. Will be going with Winter Weather Advisories for the Wind River Basin, Natrona County, and the Wind River Mountains. Will also be issuing Advisories for the Jackson and Star Valley. Snow amounts are marginally warning amounts, but some roadway melting due to the high sun angle should be enough for impacts to remain Advisory level. From Monday night through Tuesday night short-lived ridging will be overhead, which will provide a brief period of dry conditions. This quickly ends Tuesday night as moist southwesterly flow results in upslope across western WY. A strong upper low moves onto the western coast of the US Wednesday morning, and then brings more chances for precip to the CWA for Wednesday and Thursday. There is better model agreement today with this system. The upper low digs on Wednesday before it gets sheared and then lift up into WY on Thursday, which would provide lift and rain/snow to most of the CWA. It does look like temperatures will be marginal for snow, so a mix is possible for many locations. Taking a look at wind during the period, it's likely the windiest days will be today and Saturday as the upper low moves into the area. The sfc pressure gradient strengthens today as a sfc low develops in eastern WY. This will be the driver for the stronger winds today and Saturday before it weakens Saturday night. In general it will be breezy across the area through most of the period thanks to the active weather pattern. When it comes to temperatures for the next 7 days it will average out to below normal for the CWA. More cloud cover and cooler air aloft due to general troughiness will keep temperatures more like late February from Saturday through Monday. Highs will struggle to get above freezing those days. && .AVIATION...(For the 12Z TAFS through 12Z Saturday morning) Issued at 514 AM MDT Fri Mar 23 2023 West of the Divide...KBPI/KJAC/KPNA/KRKS Terminals This morning, snow showers will become prevailing as the next storm system pushes into the region. KJAC will be the first to see these snow showers and resulting IFR conditions. Snow will lighten up for a period around 00Z Saturday and continue until the end of the period. KPNA and KBPI will follow later in the morning with periods of MVFR/IFR throughout the day. Snow will begin to taper off by 00Z Saturday. KRKS will avoid most of the snow but will see a brief period of snow between 21Z Friday and 00Z Saturday. Gusty winds will also occur at KRKS beginning around 19Z Friday, with gusts around 30 to 40 kts expected through the rest of the period. East of the Divide...KCOD/KCPR/KLND/KRIW/KWRL Terminals. VFR conditions are expected to prevail through at least 00Z Friday at all terminals. Some scattered to broken mid-level clouds at 5000 to 8000ft AGL will move through most terminals tonight, but snow showers are not expected with these SCT to BKN clouds. These clouds could however result in occasional mountain obscurations. KCOD and KWRL will be the first to see prevailing snow, possibly mixed with rain starting between 20Z Friday and 00Z Saturday. Snow will remain at these terminals with MVFR/IFR conditions through the remainder of the period. KRIW and KLND will see VCSH starting around 22Z Friday with no prevailing snow expected during this period. KRIW will see winds pick up for a period of time around 03Z Saturday with gusts of 30 to 35 knots possible. KCPR will see VCSH start around 23Z Friday with light snow starting around 05Z Saturday. The winds will significantly pick up from the southwest between 03Z and 06Z Saturday with gusts of 25 to 35 knots for the remainder of the period. Please see the Aviation Weather Center and/or CWSU ZDV and ZLC for the latest information on icing and turbulence forecast && .FIRE WEATHER... Issued at 303 AM MDT Fri Mar 24 2023 Light moderate snow will develop in zones 140, 414, and 415, and 277 this morning. Snow then spreads eastward this afternoon, with the best chance of snow this afternoon in zone 279. Widespread snow arrives tonight. Heavy snow is possible in zones 275, 276, 281, 282, 285, and 287 tonight into Saturday morning. Snow spreads into zones 280, 283, 288, and 289 Saturday morning. Today will be breezy across most zones and westerly wind, with gusts to 45 mph is likely this afternoon into tonight in zones 277, 278, and 279. Windy conditions are expected behind a cold front on Saturday for the Bighorn Basin and Johnson County. North winds of 20 to 30 mph and gusts to 45 mph will occur on Saturday for these areas. Wind will also be strong across southern WY with west winds of 25 to 35 mph and gusts up to 50 mph. Smoke dispersal will improve this afternoon, with fair to very good across the area. && .RIW WATCHES/WARNINGS/ADVISORIES... Winter Storm Warning until 11 PM MDT Saturday for WYZ001-012-024. Winter Storm Warning from noon today to 11 PM MDT Saturday for WYZ002. Winter Storm Warning from 6 PM this evening to 6 AM MDT Sunday for WYZ003>006-010-011. Winter Storm Warning from 6 PM this evening to 6 PM MDT Sunday for WYZ007>009. Winter Weather Advisory until 6 PM MDT Saturday for WYZ013-023. Winter Weather Advisory from noon today to 6 AM MDT Sunday for WYZ014-015. Winter Weather Advisory from 11 PM this evening to 6 AM MDT Sunday for WYZ016>018-020. && SYNOPSIS...Rowe DISCUSSION...Rowe AVIATION...Hattings FIRE WEATHER...Rowe
Hazardous Weather Outlook National Weather Service Riverton WY 314 AM MDT Fri Mar 24 2023 WYZ001>020-022>030-251315- 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- 314 AM MDT Fri Mar 24 2023 ...Winter Storm Warnings and Winter Weather Advisories in effect for western and northern portions this morning through Saturday night... This Hazardous Weather Outlook is for Western and Central Wyoming. .DAY ONE...Today and Tonight. Widespread snow develops today, with snow continuing for the west and north through Saturday night. Highest snow amounts will be in western mountains, Bighorn Mountains, Bighorn Basin, and Johnson County. Blowing snow is possible as well, which may lead to greatly reduced visibility at times. Strong winds are expected this afternoon across southern Wyoming. .DAYS TWO THROUGH SEVEN...Saturday through Thursday. Saturday...Snow continues for western and northern portions of the area and spreads to central portions of the area. Strong winds are expected across southern Wyoming and northern Wyoming, with blowing snow likely in northern Wyoming. Sunday...Light snow continues, but accumulations will be minimal. Tuesday through Thursday...Light snow returns to western Wyoming. .SPOTTER INFORMATION STATEMENT...
The national radar mosaic for the moment the first event began.
8 winter storm. Local standard time, as filed.
Heavy snow fell in portions of the Tetons with 35 inches to the east of Alta and 22 inches at Grand Targhee.
Snowfall amounts in the Absarokas generally ranged from 10 to 15 inches.
Heavy snow fell along the East Slope of the Big Horn Mountains. The maximum amount was 16 inches at the Cloud Peak SNOTEL site.
Heavy snow fell throughout the Cody Foothills. There were widespread reports of over 6 inches of snow. The highest amount fell to the north of Cody, where 19 inches of snow was measured.
Two SNOTEL sites in the Salt and Wyoming range reported over a foot of new snow.
A trained spotter reported 7 inches of new snow in Luzerne.
A trained spotter reported 6 inches of snow to the north of Ten Sleep.
Heavy snow resulted in the closure of Highway 120 through Wind River Canyon.
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, March 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: 1089153, 1089162, 1089163, 1089158, 1089155, 1089159, 1089160, 1089161.