An upper level low passing over Wyoming developed a narrow area of heavy snow over portions of Fremont County. Heavy snow fell from the city of Riverton to Lander.
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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.
An upper level low passing over Wyoming developed a narrow area of heavy snow over portions of Fremont County. Heavy snow fell from the city of Riverton to Lander. The highest amounts were found near Lander where the airport had 10.7 inches of new snow with 6 to 9 inches around the town of Lander. In the Wind River Basin, Hudson reported 9 inches with 6 to 9 inches around Riverton. Amounts dropped sharply further north and west with less than 3 inches at the Riverton airport and points north and west.
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 3, 9:50 PM MST, 2 hours 10 minutes earlier.
Area Forecast Discussion National Weather Service Riverton WY 1050 PM MDT Mon Apr 3 2017 .SHORT TERM...(Tonight through Thursday) Early this afternoon, water vapor imagery showed one shortwave exiting eastern Wyoming, a potent trough over the southern Great Basin, and a weaker shortwave over southwestern Montana. The main player for the forecast area will be the shortwave over southwest Montana gradually sliding southeast across the Cowboy State tonight and Tuesday. The main mid-level circulation appears to slide along and west of the Divide. This will give areas along and east of the Divide a good chance of snow later tonight and Tuesday. However moisture with this system is limited due to the lead shortwave now exiting the Cowboy State, and the main system tracking well south of the area across the Four Corners/Southern Plains. However enough QG forcing and some low to mid-level convergence should be present with the mean trough for a large area to see some snowfall along and east of the Divide. Snowfall amounts look to be sub-advisory, but a few areas could approach advisory amounts especially where convergent bands of snow develop and/or typical upslope favored areas. Will handle snowfall amounts with an SPS for now. Snowfall will decrease from northwest to southeast Tuesday. Although most of the dynamics will be east of the area Tuesday afternoon, enough moisture and instability will be present for perhaps isolated snow showers redeveloping Tuesday afternoon. Soundings and thickness levels suggest much if not all of the precipitation will be in the form of snow. Tuesday night through Thursday look to be dry with a warming trend as an upper ridge builds into the Rockies. Some fog will be possible late Tuesday night/Wednesday morning in the valleys and basins from recent moisture Tuesday, clearing skies, and warming temperatures aloft. Some rapid snowmelt will occur in the lower elevations below 7500 feet Wednesday and Thursday, but snow amounts look to be low enough below 7500 feet to keep flooding concerns to be minimum. .LONG TERM...(Thursday night through Monday) Big story for the extended forecast today is the return to storminess from Friday night into Monday. High pressure will remain over the area from Thursday night into Friday night, with a few showers possible over the far western WY mountains early Friday into Friday afternoon. A large scale low pressure system is setting up on the west coast, poised to pump warm breezy to windy surface air over the state, followed my mid-level moisture. Friday thus looks to be reasonably warm with surface wind from 15 to 25 mph across much of the area. Temperatures east of the divide should easily reach the 60s and possibly low 70s Friday. Saturday should also be fairly warm east of the divide, although the ECMWF does want to push cooler air much more quickly than the GFS and Canadian models. By early Saturday, western WY though will see mostly cloudy conditions with a strong southwest moisture fetch creating a good amount of precipitation. Looks like snow levels will be about 7500-8000 feet Saturday morning, and will drop to the western valley locations by late Saturday afternoon. At this time, the primary front moving from west to east looks to be over western WY late Saturday afternoon and race to eastern WY by early Sunday morning. Widespread precipitation can be expected then Sunday, with a rain/snow mix at the lower elevations east of the divide. Up to early Sunday, the extended range models are in decent agreement with the overall pattern. After that point though, there is disagreement with the movement of the energy centers. Overall, looks like Sunday and Monday will remain unsettled and cool, although specifics are vague with regards to precipitation areas. && .AVIATION...(For the 06Z TAFS through 06Z Wednesday) A weather system will spread areas of snow across the region overnight through Tuesday morning. Expect MVFR/IFR conditions in many locations with mountain obscuration. Conditions will improve over the north after 16Z with VFR conditions prevailing by 19Z. In the central and south, conditions will improve after 18Z with VFR conditions prevailing by 23Z. VFR conditions will occur after 00Z Wed at all locations. Check terminal forecasts for more details. && .FIRE WEATHER... A quick moving storm system will bring cool and inclement weather conditions later tonight and Tuesday with breezy northerly winds developing in wake of the cold front. The best chance of snowfall with this system will be along and north of a Jackson through Lander to Casper line. Dry and warmer conditions are expected Wednesday and Thursday as a ridge of high pressure builds into the area. The next chance of precipitation could begin to impact the west Friday and spread east of the Divide Saturday and/or Sunday. && .RIW WATCHES/WARNINGS/ADVISORIES...None. && SHORT TERM...Murrell LONG TERM...McDonald AVIATION...AR FIRE WEATHER...Murrell
Hazardous Weather Outlook National Weather Service Riverton WY 348 AM MDT Mon Apr 3 2017 WYZ001>020-022>030-041100- 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- 348 AM MDT Mon Apr 3 2017 This Hazardous Weather Outlook is for Western and Central Wyoming. .DAY ONE...Today and Tonight One Weather system exits today with another waiting to sweep through the forecast area later this afternoon through tonight. Light to occasionally moderate snowfall will increase tonight from northwest to southeast, with areas along and east of the Divide above 7000 feet in the best position to accumulate snow. .DAYS TWO THROUGH SEVEN...Tuesday through Sunday Tuesday...snow showers will continue mainly east of the Divide. Snow levels are expected lower to valley basin level. Heavier snowfall can be expected along and east of the Divide above 7000 feet. Rain and snow will generally taper off from north to south Tuesday afternoon. Thursday and Friday...Warming temperatures and increasing southwest wind will result in accelerated melting of snowpack below 9000 feet with significant rises some rivers and creeks expected through Saturday. Friday night and Saturday...A cold front will likely bring significant snowfall and wind to the western mountains Friday night into Saturday morning. Western valleys will likely see mainly rain showers ahead of the cold front late Friday, changing to snow behind the cold front Friday night. .SPOTTER INFORMATION STATEMENT... Spotters are requested to report snowfall amounts or other significant weather. Thank you!
Special Weather Statement National Weather Service Riverton WY 1132 PM MDT Mon Apr 3 2017 WYZ002-003-005-007-040900- Absaroka Mountains-Cody Foothills-Southwest Big Horn Basin- Owl Creek and Bridger Mountains- Including the cities of Cody, Meeteetse, and Thermopolis 1132 PM MDT Mon Apr 3 2017 A quick moving storm system will bring some snowfall to the foothills and mountains of northern Wyoming into Tuesday morning. Total snowfall is expected to range from 2 to 6 inches over the mountains and a trace to 2 inches across the Cody Foothills and Hot Springs County. Motorists should be prepared for deteriorating road conditions, with visibility under a half mile at times in heavier snow bursts. Mountain Passes may be slick and snowpacked much of the time. WYZ015>018-040900- Wind River Mountains East-Upper Wind River Basin-Wind River Basin- Lander Foothills- Including the cities of Dubois, Riverton, Shoshoni, and Lander 1132 PM MDT Mon Apr 3 2017 A quick moving storm system will bring another round of snowfall across the Wind River Basin, and surrounding mountains through Tuesday morning. The heaviest snowfall is expected to occur now through 7 AM Tuesday. Total snowfall is expected to range from 2 to 6 inches over the mountains, a trace to 2 inches across the Wind River Basin and 2 to 3 inches in the Lander area. Motorists should be prepared for deteriorating road conditions, with visibility under a half mile in heavier snow at times. WYZ019-040900- Green Mountains and Rattlesnake Range- Including the city of Jeffrey City 1132 PM MDT Mon Apr 3 2017 A quick moving storm system will bring another round of snowfall through Tuesday afternoon across southeast Fremont County including Sweetwater Station, and Jeffrey City. The heaviest snowfall is expected to occur between midnight and 10 am Tuesday. Total snowfall is expected to range from 1 to 3 inches with locally higher amounts possible above 7000 feet. Motorists should be prepared for deteriorating road conditions, with visibility under a half mile in heavier snow bursts. WYZ020-022-040900- Natrona County Lower Elevations-Casper Mountain- Including the city of Casper 1132 PM MDT Mon Apr 3 2017 A quick moving storm system will bring another round of snowfall across Natrona County through Tuesday. Snowfall amounts late tonight and Tuesday are expected to range from half inch to 2 inches. Motorists should be prepared for deteriorating road conditions late tonight, with visibility under a mile at times in heavier snow bursts. WYZ008-009-040900- Bighorn Mountains West-Bighorn Mountains Southeast- 1132 PM MDT Mon Apr 3 2017 A quick moving storm system will bring another round of snowfall across the Bighorn Mountains through Tuesday. New snowfall amounts between 2 and 6 inches are likely, with isolated amounts around 8 inches possible. Powder River and Granite mountain passes will be slick and snowpacked at times. The heaviest snowfall is expected to occur from now through 9 AM Tuesday when visibility could be under a half mile at times. WYZ010-011-040900- Northeast Johnson County-Southeast Johnson County- Including the cities of Buffalo and Kaycee 1132 PM MDT Mon Apr 3 2017 A quick moving storm system will bring another round of snowfall across Johnson County through Tuesday. Snowfall amounts through Tuesday are expected to range from half inch to 2 inches. Motorists should be prepared for deteriorating road conditions, with visibility under a mile at times in heavier snow bursts.
The national radar mosaic for the moment the first event began.
2 winter storm. Local standard time, as filed.
Heavy snow fell from Riverton and southward. There were several reports of 6 to 9 inches of new snow. Amounts dropped sharply further north and west with Shoshoni only having 2 inches of snow.
The observer at the Lander airport measured 10.7 inches of new snow. Measurements of 6 to 9 inches were common around the city of Lander.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Wyoming in 2017Every state in 2017This day in weather historyWarnings in Wyoming, April 2017
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: 683943, 683947.