A wet and unusually cold low pressure system brought heavy snow to portions of the mountainous terrain. The heaviest snow was in the Absarokas where 18 inches of new snow fell.
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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.
A wet and unusually cold low pressure system brought heavy snow to portions of the mountainous terrain. The heaviest snow was in the Absarokas where 18 inches of new snow fell. Some other amounts included 16 inches in the Bighorns and 14 inches in the Wind River Range.
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 May 27, 4:53 PM MST, 1 hour 7 minutes earlier.
Area Forecast Discussion National Weather Service Riverton WY 553 PM MDT Mon May 27 2019 .SHORT TERM...This afternoon through Tuesday The closed upper low continues its slow trek over NV/AZ/UT, with shortwaves moving north-northwest over the Cowboy State this afternoon. Broad difluent flow also continues over the area today, with extensive areas of rain occurring mainly over central portions so far. Locally heavy rain has already occurred earlier this morning over portions of the Wind River Basin and southern portions of the Bighorn Basin. This activity is expected to shift to northern portions through the afternoon and into the evening hours, as the upper low slowly makes its way over W CO. Snow levels remain high today, ranging between 8500 and 9000 feet. This will lessen the rain on snow threat somewhat, but will lead to moderate to heavy snow potential over the Bighorn, Absaroka and Wind River Mountains. Snow levels are not expected to lower until after midnight, dropping between 7500 to 8500 by sunrise Tuesday morning. Total snow amounts in the Winds and Absarokas look to be around 12 to 16 inches, with the higher terrain seeing amounts over 20 inches. The Bighorn's totals are a bit higher at 15 to 20 inches, with some areas getting into the 30 inch range. We have issued Winter Storm Warnings to cover these areas, including specifics of elevations above 8000 feet and that South Pass will only see 3 to 5 inches. Rain will shift back southward Tuesday, as the upper level low continues its slow trek toward extreme NE CO. This will increase chances for rain across central Wyoming again through Tuesday afternoon. Rain will begin to taper off over NW WY late Tuesday afternoon, with rain chances decreasing from northwest to southeast through the evening, as the upper low pushes into NE. Rainfall amounts of 1.5 to 3 inches remain forecasted for areas east of the Divide. 1 to 1.75 inches are expected for much of the central basins, with 2 to 3 inches over Johnson County. The Flood Watch and Winter Storm Warnings remain in effect through Tuesday. .LONG TERM...Tuesday night through Monday Wednesday night and Thursday will see an upper level high over the Northern High Plains keeping much of the forecast area in drier, slightly warmer weather. There will be a weak upper trough across the Intermountain West, which will produce showers and thunderstorms for the west on Thursday afternoon and evening. This upper trough is expected to slowly progress eastward through the period with the trough axis moving into central WY over the weekend. The shower activity will increase in coverage and spread into central areas Friday and Saturday as the upper trough moves into the Great Basin. On Sunday, a stronger upper trough moves in from the Pacific NW and accelerates across the Divide replacing the weaker trough. Chances of showers and thunderstorms will remain across the area on Sunday with a somewhat drier westerly flow prevailing on Monday High temperatures will generally be slightly below seasonal normals through the period with valleys and basins mostly in the 60s to && .AVIATION...(For the 00Z TAFS through 00Z Tuesday evening) Issued at 547 PM MDT Mon May 27 2019 Will continue with trending that rain will be generally continuous over many of the TAF sites thought tonight and will keep IFR/MVFR ceilings and visibilities as prevailing at most locations through the balance of the forecast. Expect mountains to be frequently obscured through Tuesday morning. Expect also that isolated thunderstorms remaining a possibility through about 02Z tonight and especially at KRKS in southern portion of the area. Current trending indicates that most of the rain should be east of the Continental Divide through about 15Z Tuesday, with rain becoming more scattered west of the Divide tonight and into Tuesday. A slow increase in visibilities and ceilings are expected on Tuesday, especially after 18Z at most TAF sites. Please see individual terminals for more details. Please refer to Aviation Weather Center products for more information on icing and turbulence forecasts. && .FIRE WEATHER... Issued AT 1155 AM MDT Mon May 27 2019 A cold front across Wyoming will produce widespread rain, heavy at times, through Tuesday evening, especially east of the Divide. The heaviest rain is likely to fall between this afternoon until about sunset Tuesday, with 1.5 to 3 inches falling in Johnson and Natrona counties. Widespread one-half to one inch amounts are expected in many other locations. Temperatures will be cooler than normal today, with cloudy skies across the state. Tuesday will find a gusty north wind of 20 to 35 mph across northern Wyoming. && .RIW WATCHES/WARNINGS/ADVISORIES... Flood Watch through Tuesday afternoon for WYZ009>011-020-022. Winter Storm Warning until 6 PM MDT Tuesday for WYZ002-008-009- 014-015. && SHORT TERM...Lavoie LONG TERM...Swanson AVIATION...Troutman FIRE WEATHER...Swanson
Hazardous Weather Outlook National Weather Service Riverton WY 322 AM MDT Mon May 27 2019 WYZ001>020-022>030-280930- 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- 322 AM MDT Mon May 27 2019 ...Flood Watch from Noon Today through Tuesday afternoon for Johnson and Natrona Counties... ...Winter Storm Warning from 6 PM this evening to Noon Tuesday for the Absaroka, Wind River and Bighorn Mountains... This Hazardous Weather Outlook is for Western and Central Wyoming. .DAY ONE...Today and Tonight. Rain likely with high elevation snow. Snow levels will lower to near 8000 feet across central Wyoming tonight with heavy, wet snow developing in the mountains. Rain could be heavy at times across central Wyoming. Rainfall amounts of 1 to 2.5 inches are possible across central Wyoming, with the heaviest amounts expected across Johnson and Natrona Counties. Please see Winter Storm Warnings and Flood Watches for the latest information. .DAYS TWO THROUGH SEVEN...Tuesday through Sunday. Tuesday...Areas of moderate to heavy rain continuing across the lower elevations of central Wyoming with heavy wet snow in the mountains. Precipitation tapering off north to south Tuesday night. Thursday through Sunday...Isolated to scattered afternoon and evening thunderstorms. .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.
3 winter storm. Local standard time, as filed.
The Cloud Peak SNOTEL site received 16 inches of new snow.
Heavy snow fell in portions of the Absarokas. The highest amount was 18 inches at the Marquette SNOTEL site.
The Cold Springs SNOTEL site received 14 inches of new snow.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Wyoming in 2019Every state in 2019This day in weather historyWarnings in Wyoming, May 2019
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: 822475, 822476, 822479.