A locally heavy snow band set up over the Star Valley. The highest amounts of snow were around Thayne where 6 to 13 inches of new snow fell.
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The episode as NWS RIW wrote it up.
A locally heavy snow band set up over the Star Valley. The highest amounts of snow were around Thayne where 6 to 13 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 Mar 22, 3:49 AM MST, 2 hours 11 minutes earlier.
Area Forecast Discussion National Weather Service Riverton WY 449 AM MDT Wed Mar 22 2023 .DISCUSSION...Today through Tuesday Issued at 234 AM MDT Wed Mar 22 2023 Snow remains confined to southwestern portions so far this morning, mainly impacting the Upper Green River Basin and Lincoln County. This is due to a lead shortwave moving over northern portions of UT/NV, marked by cold cloud tops. Snow will remain light over these areas through the rest of the night, with an inch of accumulation possible before sunrise. At the same time, light snow will also develop over southern Fremont County to western Natrona County. Accumulations will be minor in these areas. The main upper level low is over southern NV as of 07Z and is expected to quickly move northeastward over southwestern WY by 18Z. Snow will become widespread across central and southern portions of the forecast area by sunrise, as the left front quadrant will be overhead to provide ample lift. The jet will also advect Pacific moisture across the region, leading to the widespread snow. Another component of this increased moisture will be the increased instability. CAPE values of 100-200 J/kg will occur across much of the area west of the Divide and over portions of Fremont and Natrona counties. The snow will be much more convective in nature this afternoon, as a result. 3 to 5 inches of snow are still expected from the Red Desert to southern Johnson County, however locally higher amounts of 6 or 7 inches will be possible. Additionally, visibilities could be reduced to 1/2 mile or less due to the convective nature of these snow bands. Western portions are still expected to receive 3 to 5 inches, with 5 to 10 inches in the mountains. Portions of Sweetwater and Sublette counties may only receive 1 to 3 inches from this storm. The Bighorn Basin and northern portions of Johnson County will have little to no impacts. Snow will end across all, but western portions before midnight. A major change from previous shifts is the influence of the boundary that pushed southward yesterday. This boundary is now over portions of Sweetwater County, with a weak sfc low located near Green River/La Barge. The strong southwest winds that were forecasted to occur over the Wind Corridor today will now be confined over the "warm" sector of this boundary, namely the eastern half of Sweetwater County. Gusts of 35 to 45 mph will develop this afternoon, occurring along and south of a Rock Springs to Bairoil line. West-southwest winds, with gusts up to 30 mph, will occur over southern Lincoln, Sublette and western Sweetwater counties as the sfc low moves toward southern Natrona County this afternoon. As previously mentioned, light snow will remain possible over western portions tonight, as weak upslope flow continues due to a more westerly flow pattern in the wake of the storm. This activity will continue Thursday into Friday, as another storm moves onshore Thursday night into Friday. Strong winds, with gusts of 35 to 45 mph, look to be widespread across western and southern portions Friday, as the shortwave moves over the area. An elongated longwave trough will develop over much of the northern CONUS by Saturday. A series of shortwaves will bring chances for snow over northern portions starting Friday night and continue into Sunday. Snow will end across the area Monday, as these shortwaves exit eastward. A shortwave ridge will build over the region Tuesday, as another closed low drops southward off the PACNW coast. This would lead to increased southwest winds over the Wind Corridor and possibly mix the colder air in the basins. && .AVIATION...For the 12Z TAFS through 12Z Thursday Issued at 449 AM MDT Wed Mar 22 2023 An area of snow across the southwest will continue to spread north with a line of snow developing from KJAC- KRIW- KCPR through 14Z. At the same time, another area of snow will develop over southern portions between 15Z and 18Z. The first batch of snow is expected to push north into the Bighorn Basin and Johnson County at the same time. There are hints of very heavy snow bands (snow squall) impacting areas from central/eastern Sweetwater County pushing northeast across Natrona County between 21Z Wednesday and 03Z Thursday. Most of the snowfall will end east of the Divide and the south by around 06Z Thursday. However some snow will continue across the far west through 12Z Thursday. Exact timing and persistence of snow at a given terminal is only moderate with models showing a possible 2 to 4 hour break in the snow between 15Z and 21Z depending upon what terminal. There will be IFR/MVFR visibilities and MVFR ceilings at most terminals for a considerable amount of time through 06Z Thursday. The exception will be the far north at KCOD and KWRL, where impacts are expected to be less. LIFR conditions are likely at times due to the low visibility and vertical visibility, due to heavier bouts of snow. 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 234 AM MDT Wed Mar 22 2023 Snow will become widespread across all but northern portions this morning. Convective snow bands will be possible this afternoon over zones 280/289, where locally heavy snow could occur. Southwest winds, with gusts of 35 to 45 mph, will be confined to zone 279. Snow will end across much of the area before midnight. Light snow will continue over western portions tonight into Thursday. Snow will stay persistent over the west through Friday and possibly Saturday. West-northwest winds, with gusts of 30 to 40 mph, will be widespread across western and southern portions Friday. && .RIW WATCHES/WARNINGS/ADVISORIES... Winter Weather Advisory until 11 PM MDT this evening for WYZ007- 016>020-022. Winter Weather Advisory from 9 AM this morning to 11 PM MDT this evening for WYZ009>011. Winter Weather Advisory until 6 AM MDT Thursday for WYZ012>015- 023>027. Winter Weather Advisory until 11 PM MDT this evening for WYZ028- 030. && DISCUSSION...LaVoie AVIATION...Murrell/LaVoie FIRE WEATHER...LaVoie
Hazardous Weather Outlook National Weather Service Riverton WY 253 AM MDT Wed Mar 22 2023 WYZ001>020-022>030-231300- 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- 253 AM MDT Wed Mar 22 2023 ...Winter Weather Advisories remain in effect through Thursday morning for most of western, central, and southern Wyoming... This Hazardous Weather Outlook is for Western and Central Wyoming. .DAY ONE...This afternoon and tonight. Snow showers will occur across central and southern portions through the day today, before ending later this evening. Convective snow bands, with locally heavy snow, will be possible, especially over portions of Natrona County and southern Fremont County. Southwest winds, with gusts of 35 to 45 mph, will be confined to the eastern half of Sweetwater County. Light snow will continue over western portions late tonight. .DAYS TWO THROUGH SEVEN...Thursday through Tuesday. Thursday and Friday...Snow will continue over the western WY mountains, as another storm system approaches the area. Parts of central and southern WY could see strong winds on Friday. Saturday and Sunday...Temperatures will stay below normal. Light to moderate snow will be possible over the northern half of the forecast area. .SPOTTER INFORMATION STATEMENT... Weather spotters are encouraged to report significant weather conditions according to standard operating procedures.
The national radar mosaic for the moment the first event began.
1 winter storm. Local standard time, as filed.
CoCoRaHS observers reported 6 to 13 inches of new snow around Thayne.
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: 1089148.