A strong cold front moving into northern Wyoming combined with potent jet dynamics to produce heavy snow across portions of northern Wyoming. Over a foot of snow fell in portions of Yellowstone Park, the Tetons and the Absarokas.
Every event with a place to put it; 7 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 strong cold front moving into northern Wyoming combined with potent jet dynamics to produce heavy snow across portions of northern Wyoming. Over a foot of snow fell in portions of Yellowstone Park, the Tetons and the Absarokas. Heavy snow fell across the lower elevations as well. Up to 8 inches fell around the Cody area and combined with strong winds to produce near zero visibility and road closures. Strong winds and heavy snow also combined to close roads in northern Johnson County. Further south, high winds were the problem in portions of Fremont and Sweetwater Counties. Winds gusted to 71 mph at Fales Rock RAWS site and 63 mph at Bitter Creek along Interstate 80.
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 Apr 1, 1:47 PM MST, 7 hours 13 minutes earlier.
Area Forecast Discussion National Weather Service Riverton WY 247 PM MDT Sun Apr 1 2018 .SHORT TERM...(This evening through Wednesday) Issued at 246 PM MDT Sun Apr 1 2018 Snow will move in this evening as a Pacific low pressure trough moves into the Pacific Northwest. The snow will be associated with strong winds on the higher ridges and passes. Snowfall may become heavy at times. The wind and snow intensity is expected to peak out very early Monday morning over the western mountains shifting to areas over and east of the Continental Divide where high winds are expected to spread into the lower elevations. Snowfall of 8 to 14 inches is likely in the Tetons with lower amounts in the Wyoming and Salt River, and Gros Ventre mountains. The snowfall will shift into northern Wyoming Monday and Monday night with heavier snowfall expected in the Bighorn mountains where a winter storm watch is in effect. Tuesday will be colder with drying as high pressure moves into the area behind the storm. Wednesday will see some snow increase in the northwest with warming most areas and increasing winds in and near the mountains. .LONG TERM...(Wednesday night through Sunday) Issued at 246 PM MDT Sun Apr 1 2018 Beginning of forecast: Unsettled , moderately moist northwest flow continues across the forecast area with persistent ridge in place. The area will be between primary jet action, but still under decent flow (70-90kts). Lingering light mountain snow across northern WY continues. Overall, MR models, with the exception of minor height differences at 700mb and above continue in decent agreement through the end of the forecast period. Persistent northwest flow aloft continues with weak to modest moisture flow from out of the PAC NW/Southwestern Canada. The "storm track" will tend to remain primarily from central WY northward until Thursday when it begins to sag a bit further south as a Pacific modified piece of the northern branch of the jet and an associated shortwave try to flatten the western ridge just a bit. The northwest flow, however, will keep things unsettled (light intermittent orographic or diurnally forced showers) until the next period of enhancement (embedded shortwave/jet) approach and move across/near the region Thursday night. Increasing moisture and slightly better dynamics aloft arrive across the western forecast area by the beginning of this forecast. Model timing having sped up some over the last 24 hrs (expected in fast NW flow conditions), Thursday mid- day the shortwave/jet combo will be located near/over portions of NW WY. This should flatten the ridge slightly across the west and allow the shortwave energy to penetrate further to the south, increasing precip chances across southwest/southern WY Friday morning. Frontogenesis, that will have been taking place during the day Thursday, will push a clipper type front into northern/northeastern WY east of the Divide in the afternoon/evening. Therefore, Thursday precip chances will start across northwest WY (morning), then spread over far northern WY with the front (afternoon), moving into portions of central WY (Johnson/Natrona Counties) Thursday night. Friday much of Wyoming will be covered with cloud and some chance for precipitation (Moderate chances across the western mountains with accumulating snow rising from the mid 7000s(ft) to somewhere near 8500 feet by Friday afternoon as the ridge opens eastward, influencing the western CWA.). Low (lower elevations) to moderate (mountains) chances of precipitation expected east of the Divide... most as rain. Saturday, the trough/ridge/trough pattern across the CONUS amplifies. Now, with more strengthening/amplifying of the PAC NW trough...a delay in timing is showing up in the models with respect to kicking the ridge out of the way Saturday. Concurrent frontal and shortwave passage is now running some 6 or so hours behind solutions of the last few days. Will see if this trend continues. Regardless, a messy weekend looks on tap. && .AVIATION...(For the 00Z TAFS through 00Z Tuesday) Issued at 246 PM MDT Sun Apr 1 2018 West of the Divide...KBPI/KJAC/KPNA/KRKS Routes Mountains will also be obscured at times throughout the forecast period. VFR conditions will prevail for all terminal sites except KJAC through mid-day Monday. KJAC will see a return to MVFR/IFR by/after 05Z Monday as the next weather system with rain/snow moves into western WY after 02Z Monday. Monday afternoon, increasing chances for cloud and precipitation will begin to effect the remaining terminal locations with MVFR conditions. Additionally, gusty west/southwest winds will occur at all terminal sites by mid- morning Monday and continue through the the rest of the forecast period. Winds will be strongest at KRKS. East of the Divide...KCOD/KCPR/KLND/KRIW/KWRL Routes VFR conditions will prevail at all terminal sites through the forecast period - except for KCOD which remain VFR until around 14Z Monday - and KWRL until around 19Z. By/after 14Z Monday, a cold front will begin to pass through northern WY (including KCOD...followed by KWRL later in the morning), shifting the wind to the north, lowering ceilings and bringing a chance for snow with reduced VIS. Additionally, gusty west/southwest winds will return/occur at most terminal sites (except KCOD and KWRL) by mid- morning Monday and continue through rest of the end of the forecast period. Winds will be strongest at KCPR. && .FIRE WEATHER... Issued AT 246 PM MDT Sun Apr 1 2018 Snow will move in this evening as a Pacific low pressure trough moves into the Pacific Northwest. The snow will be associated with strong winds on the higher ridges and passes. Snowfall may become heavy at times. The wind and snow intensity is expected to peak out very early Monday morning over the western mountains shifting to areas over and east of the Continental Divide where high winds are expected to spread into the lower elevations. Snowfall of 8 to 14 inches is likely in the Tetons with lower amounts in the Wyoming and Salt River, and Gros Ventre mountains. The snowfall will shift into northern Wyoming Monday and Monday night with heavier snowfall expected in the Bighorn mountains where a winter storm watch is in effect. Tuesday will be colder with drying as high pressure moves into the area behind the storm. Wednesday will see some snow increase in the northwest with warming most areas and increasing winds in and near the mountains. Monday the windy areas will have good to better smoke dispersal while the snowy areas in the mountains and north will have poor smoke dispersal. With partial clearing on Tuesday most areas will mix better resulting in good smoke dispersal. && .RIW WATCHES/WARNINGS/ADVISORIES... High Wind Watch from Monday afternoon through Monday evening for WYZ004-016-017-027>030. High Wind Warning from 3 AM Monday to midnight MDT Monday night for WYZ015-018-019. Winter Storm Warning from 6 PM this evening to midnight MDT Monday night for WYZ001-002-012. High Wind Watch from Monday afternoon through Monday evening for WYZ010. Winter Storm Watch from Monday morning through Monday evening for WYZ008-009. && SHORT TERM...Baker LONG TERM...Braun AVIATION...Braun FIRE WEATHER...Baker
Hazardous Weather Outlook National Weather Service Riverton WY 312 AM MDT Sun Apr 1 2018 WYZ001>020-022>030-021100- 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- 312 AM MDT Sun Apr 1 2018 ...Winter Storm Watches in Effect for the Northern Mountains Tonight through Monday Evening... ...High Wind Watches in Effect for Portions of South and Central Wyoming Late Tonight through Monday Evening... This Hazardous Weather Outlook is for Western and Central Wyoming. .DAY ONE...Today and Tonight. Valley rain or a rain/snow mix and mountain snow will increase across western Wyoming tonight. Strong winds with gusts over 60 mph may develop down the east slopes of the Wind River Mountains into the Lander Foothills and South Pass area late tonight. .DAYS TWO THROUGH SEVEN...Monday through Saturday Monday and Monday night...A strong cold front will push across the area Monday. Snow, heavy at times, along with blowing and drifting snow is expected to impact much of western Wyoming Monday morning into the afternoon. Please see Winter Storm Watches for more information. High winds are possible across portions of central and southern Wyoming, including the Interstate 80 corridor, through Monday evening. Please see High Wind Watches for the latest information. .SPOTTER INFORMATION STATEMENT... Please report snow amounts,wind gusts over 50 mph, or any wind damage. Thank you.
The national radar mosaic for the moment the first event began.
5 winter storm, 2 high wind. Local standard time, as filed.
Heavy snow fell in portions of Yellowstone. The highest amount was 13 inches at Sylvan Lake.
Heavy snow fell in portions of the Absarokas. The highest amount was 16 inches at the Beartooth Lake SNOTEL site.
At the top of the Jackson Hole Ski Resort, a foot of new snow fell.
Heavy snow fell in portions of the Cody Foothills. Some of the heaviest amounts included 10 inches west of Meeteetse and 8.5 inches west of Cody. The snow combined with strong winds to sharply reduce visibility and bring numerous road closures during the afternoon and evening hours of April 2nd.
Periods of snow combined with strong winds to bring difficult travel conditions. Interstates 25 and 90 were shut down due to white out conditions and drifting snow from portions of April 2nd to April 3rd. The highest snowfall amount recorded was 4 inches southwest of Buffalo.
The Fales Rock RAWS site had several wind gusts over 58 mph, including a maximum gust of 71 mph.
A wind gust of 63 mph was reported at Bitter Creek along Interstate 80.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Wyoming in 2018Every state in 2018This day in weather historyWarnings in Wyoming, April 2018
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: 748192, 748193, 748194, 748195, 748196, 748444, 748445.