A fetch of Pacific moisture moved into Wyoming and brought locally heavy snow to the Wind River Range. A foot of new snow was recorded at SNOTEL sites near South Pass City.
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The episode as NWS RIW wrote it up.
A fetch of Pacific moisture moved into Wyoming and brought locally heavy snow to the Wind River Range. A foot of new snow was recorded at SNOTEL sites near South Pass City.
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 30, 4:06 AM MST, 1 hour 54 minutes earlier. Its key messages:
Area Forecast Discussion National Weather Service Riverton WY 506 AM MDT Sat Mar 30 2024 .KEY MESSAGES... - Round of rain and snow Saturday with cooler temperatures expected. - A heavier round of snow and rain Sunday with more significant accumulations likely with even cooler temperatures to be had. - Warming and mainly dry trend throughout the week. && .DISCUSSION... Issued at 1255 AM MDT Sat Mar 30 2024 IR currently depicts the deep longwave trough over the Sierra Nevadas with ample southwest flow moisture progging into the southern half of the CWA. Relatively quiet currently on radar but a big swath of rain and snow is pushing out of northeastern Utah that will begin to enter the southern CWA towards sunrise Saturday morning. Light snow likely towards the I-80 corridor through the early morning turning more towards a rain and snow mix by mid morning with warming temperatures above freezing. As this shortwave supporting this precipitation extends further northward, expect mainly rain east of the Divide and snow to snow/rain mix to the west. With cloudy conditions, cooler temperatures are to be had through the afternoon hours. Short term models are depicting a brief period of mainly dry weather late afternoon and into the evening hours ahead of another stronger shortwave that will push in through the overnight hours. Southwest divergent flow aloft will continue to deepen the aforementioned longwave trough as it moves slowly east overnight into Sunday. Temperatures will be the big player for Sunday in terms of precipitation type for the lower basins east of the Divide. Some light snow should begin the morning before a quick transition to rain throughout much of the day before turning back to snow by the end of the afternoon as cooler air looks to push in a bit quicker with this set of model runs. Still some uncertainty as models are not in total agreement on this cooler push but this will determine final snow accumulations through the overnight hours into Monday morning. Higher terrain to include passes west of the Divide will see the highest accumulations but minimal lower valley impacts. With the warmer temperatures and road conditions, even the several inches of snow will be wet in nature and lower in snow ratio. Much of the lower basins to the east will see more accumulations in liquid precipitation with a probability of 2 to 4 inches the greatest (~40-60%) as snow levels dip from the 6-7kft range down to 4-5kft later in the day, indicated by the dropping 700mb temperatures. Any amounts higher will be constrained to the higher terrain but passes and the canyon through the Owl Creeks should be the most impacted at this point in time that were added to the current advisory. Otherwise, the cooler than average temperatures will persist through Sunday under the cloudy skies into Monday. Winds will remain relatively light with the higher gusts up to 20-30 mph possible for the afternoon hours in the wind corridor from South Pass through Muddy Gap to Casper. This longwave trough will move east of the CWA by late Monday morning and into the afternoon as positively tilted ridging builds in from the southwest with increasing convergence to support it. This will bring in milder temperatures with a warming trend throughout the work week and into next weekend. Another deep low will push southeast from the GOA to the Pacific Northwest by mid week and should start to see some affects by mid Thursday for western mountains before expanding to the valleys in the afternoon. Uncertainty exists with quite much contrast in model placement on the aforementioned low's movement southward as southwest flow returns at that time. A more mild and warmer low, expect minimal temperature changes with rain the most likely scenario for lower valleys capping the snow to the higher mountains west of the Divide. With the current track, areas to the east should see minimal impacts if any at this time. Stay tuned for updates in the coming days after this current system passes through. && .AVIATION /12Z TAFS THROUGH 12Z SUNDAY/... Issued at 505 AM MDT Sat Mar 30 2024 Snow and rain chances increase from southern Wyoming to northern through the morning and early afternoon. Models indicate that the initial push is stratiform snow, transitioning to scattered rain/snow showers by late morning and through the afternoon. Some sites may see a transition to all rain for the afternoon. Precipitation chances decrease a bit by this evening, before another round of rain/snow occurs towards the end of the TAF period and especially after, into Sunday. Mountain obscuration expected through the TAF period. Please see the Aviation Weather Center and/or CWSU ZDV and ZLC for the latest information on icing and turbulence forecasts. && .RIW WATCHES/WARNINGS/ADVISORIES... Winter Weather Advisory until 11 PM MDT Sunday for WYZ002-007. Winter Weather Advisory until 6 AM MDT Monday for WYZ008-009. Winter Weather Advisory until 11 PM MDT Sunday for WYZ012-024. Winter Storm Warning until 11 PM MDT Sunday for WYZ014-015. && DISCUSSION...Lowe AVIATION...Wittmann
Hazardous Weather Outlook National Weather Service Riverton WY 126 AM MDT Sat Mar 30 2024 WYZ001>020-022>030-311130- Yellowstone National Park-Absaroka Mountains-Cody Foothills- North Bighorn Basin-Southwest Bighorn Basin-Southeast Bighorn 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- 126 AM MDT Sat Mar 30 2024 This Hazardous Weather Outlook is for Western and Central Wyoming. .DAY ONE...Today and Tonight. Snow will being to push in from the south and southwest Saturday morning expanding north throughout the day. Most impacts for the higher terrain, especially along and west of the Divide. Rain and rain/snow mix for lower basins east with a brief break overnight into Sunday morning. .DAYS TWO THROUGH SEVEN...Sunday through Friday. A stronger round of snow west of the Divide and rain to rain/snow mix for lower basins to the east. All snow expected after sunset Sunday and into the overnight hours through Monday morning. Dry and warmer conditions expected Monday through mid week before another system nears from the northwest by Thursday. .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.
2 winter storm. Local standard time, as filed.
The Larson Creek SNOTEL recorded 12 inches of new snow.
The Deer Park SNOTEL site recorded 12 inches of new snow.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Wyoming in 2024Every state in 2024This day in weather historyWarnings in Wyoming, March 2024
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: 1168283, 1168284.