Four skiers were climbing the Sickle Couloir on Mount Moran in Grand Teton National Park on Sunday morning, May 17, when a shallow, wet avalanche broke from above. Three of the four skiers were swept 500 feet downhill over rock and ice.
Every event with a place to put it; 1 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.
Four skiers were climbing the Sickle Couloir on Mount Moran in Grand Teton National Park on Sunday morning, May 17, when a shallow, wet avalanche broke from above. Three of the four skiers were swept 500 feet downhill over rock and ice. One man was killed on the mountain and another succumbed to his injuries three days later. The injured skier was able to descend the slope on his own. Following the initial call for help around 0830MST, the skiers were attended to by National Park Service Search and Rescue rangers.
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 17, 2:15 AM MST, 6 hours 15 minutes earlier.
AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE RIVERTON WY 315 AM MDT SUN MAY 17 2015 .SHORT TERM...SUNDAY THROUGH TUESDAY NIGHT ANOTHER DAY...ANOTHER REPORT OF SEVERE WEATHER. YESTERDAY THE ACTION WAS AGAIN IN PARK COUNTY WHERE THERE WERE SEVERAL FUNNEL CLOUDS AND EVEN A CONFIRMED TOUCHDOWN OF A WEAK TORNADO. TODAY LOOKS LIKE ANOTHER UNSETTLED DAY AS WELL AS AN UPPER LEVEL LOW CONTINUES TO SLOWLY MOVE ACROSS THE STATE AND SOME MOISTURE WRAPS AROUND FROM A SURFACE LOW IN THE NORTHERN PLAINS. THIS MEANS ANOTHER MOSTLY CLOUDY DAY WITH MORE SHOWERS AND A FEW THUNDERSTORMS. HOWEVER...IT WILL BE ABOUT 5 TO 10 DEGREES COOLER EAST OF THE DIVIDE AFTER THE PASSAGE OF A COLD FRONT AND AS A RESULT...ALMOST ALL THE CAPE AND NEGATIVE LIFTED INDICES ARE MAINLY ACROSS WESTERN AND SOUTHERN AREAS SO WE CONFINED THUNDER TO THOSE LOCATIONS. WE CAN'T RULE OUT A RUMBLE OF THUNDER ELSEWHERE...BUT IT SHOULD BE MORE STABLE TODAY. THERE IS STILL SOME SHEAR THOUGH SO I WOULD NOT BE SURPRISED TO SEE A REPORT OF A COLD AIR FUNNEL IN SPOTS THOUGH. AS FOR SNOW LEVEL...THE MODELS HAVE TRENDED A BIT WARMER WITH 700 MILLIBAR TEMPERATURES BOTTOMING OUT AT MINUS 3 WHICH WOULD BUT THE LEVELS AROUND 7000 FEET WITH MOST NOT STICKING EXCEPT FOR THE HIGHER ELEVATIONS. IN ADDITION...AREAS THAT HAVE GUSTY WINDS WITH COLD ADVECTION FOLLOWING A COLD FRONT...LIKE THE NORTHERN BIG HORN BASIN AND JOHNSON COUNTY WILL SEE GUSTY NORTH TO NORTHWEST WINDS THROUGH THE DAY...BUT NOT TO HIGH WIND LEVEL. WE WILL CONTINUE THE SPS AS THAT SEEMS SUFFICIENT. THE COVERAGE OF SHOWERS SHOULD DECREASE TONIGHT AS SHORTWAVE RIDGING BUILDS ACROSS THE AREA TONIGHT. FOR MONDAY...IT LOOKS LIKE THE DRIEST OF THE THREE DAYS OF THE SHORT TERM ACROSS THE BODY OF THE FORECAST AREA. ANOTHER SHOT OF MOISTURE WILL MOVE IN FROM THE SOUTHWEST...BUT SHOULD BE A MAINLY CONFINED TO AREAS WEST OF THE DIVIDE THROUGH MOST OF THE DAY. EVEN THERE...ACTIVITY SHOULD BE SCATTERED SO MOST OF THE DAY SHOULD BE RAIN FREE. MOISTURE WILL BEGIN TO SPREAD ACROSS THE DIVIDE DURING THE EVENING HOURS AND INTO THE NIGHT. THIS DAY ALSO LOOKS TO BE THE MILDEST DAY OF THE NEXT THREE. DEEPER MOISTURE THEN MOVES INTO THE AREA AS ANOTHER UPPER LEVEL LOW MOVES TOWARDS WYOMING FOR TUESDAY AND SPREADS MORE MOISTURE ACROSS THE AREA. THIS LOOKS LIKE THE WETTEST AND COOLEST DAY OF THE THREE. WITH DEEPER MOISTURE AND LARGELY STABLE AIR ACROSS AREAS EAST OF THE DIVIDE FOR TUESDAY...WE DECIDED TO GO WITH JUST PLAIN RAIN AND NOT SHOWERS. WEST OF THE DIVIDE...WHERE THINGS MAY BE MORE UNSTABLE WE KEPT THINGS MORE CONVECTIVE THOUGH. AND ONCE AGAIN...WITH CHILLY AIR IN PLACE SOME OF THE HIGHER ELEVATIONS COULD EVEN SEE SOME SNOW ON TUESDAY NIGHT. .LONG TERM...WEDNESDAY THROUGH SUNDAY SYNOPSIS...THE OVERALL PATTERN OF COOL AND SHOWERY WEATHER WILL CONTINUE THROUGH THIS PERIOD WITH THE NEXT PACIFIC STORM SYSTEM IMPACTING THE AREA PRIMARILY ON FRIDAY AND SATURDAY. DISCUSSION...BLOCKING RIDGE OVER WESTERN CANADA FORECAST TO REMAIN THROUGH MEMORIAL DAY WEEKEND AND BEYOND. PACIFIC STORM SYSTEMS MOVING INTO THE NORTHEAST PACIFIC WILL CONTINUE TO SPLIT AROUND THIS RIDGE WITH THE SOUTHERN END OF THE SPLIT TAKING THE STORMS SOUTH OFF THE WEST COAST BEFORE TURNING EAST INTO SOUTHERN CALIFORNIA...THEN LIFTING NE ACROSS THE GREAT BASIN AND CENTRAL ROCKIES...WITH STORMS SPACED AROUND 72 HOURS APART. THIS COOL AND WET PATTERN FOR THE AREA IS EXPECTED TO CONTINUE WELL INTO THE FINAL WEEK OF MAY. THE NEXT IN THIS SERIES OF STORMS WILL SHEAR OUT ACROSS CENTRAL/EASTERN WYOMING INTO THE HIGH PLAINS ON WEDNESDAY WITH UPPER RIDGE PUSHING UP FROM WEST TEXAS ACROSS THE DIVIDE WEDNESDAY NIGHT. AREAS EAST OF THE DIVIDE WILL SEE SCT-NMRS SHOWERS UNDER THE UPPER LOW DURING THE DAY WEDNESDAY WHILE THE SOUTH AND WEST WILL SEE A BIT MORE INSTABILITY AND SOME THUNDERSTORMS BLOSSOMING IN THE AFTERNOON. THERE SHOULD BE A LETUP IN PRECIPITATION WEDNESDAY NIGHT INTO THURSDAY MORNING BETWEEN SYSTEMS. THE NEXT STORM SYSTEM IN THIS SERIES WILL PUSH INTO SOUTHERN CALIFORNIA LATE THURSDAY WITH SOUTHERLY DIFLUENT DOWNSTREAM ACROSS THE GREAT BASIN AND CENTRAL ROCKIES THURSDAY AFTERNOON/EVENING. MOISTURE AND INSTABILITY AND THUS SHOWER AND THUNDERSTORM ACTIVITY WILL BE BEST ACROSS THE SOUTH AND WEST...UP TO NEAR A CPR-RIW LINE WITH A MORE STABLE AIRMASS OVER NE WYOMING...WHERE SHOWERS AND THUNDERSTORMS SHOULD WEAKEN AS THEY MOVE UP FROM THE SOUTH. THE MAIN UPPER LOW IS EXPECTED TO LIFT NE ACROSS THE GREAT BASIN AND CENTRAL ROCKIES FRIDAY AND SATURDAY WITH AT LEAST SCATTERED SHOWERS ACROSS THE AREA WITH SOME THUNDERSTORMS IN THE AFTERNOON/EVE. THIS SYSTEM WILL THEN LIFT ACROSS THE PLAINS ON SUNDAY. BOTH GFS AND ECMWF SHOW AN UPPER LOW BECOMING TRAPPED UNDER THE WESTERN CANADIAN RIDGE OVER THE NW U.S. SUNDAY...BUT CONFIDENCE IS LOW IN THIS SCENARIO AND WOULD PREFER PERSISTENCE IN THIS BLOCKING PATTERN WITH WITH NEXT SOUTHERN STREAM LOW MAKING LANDFALL ON THE S CA COAST AROUND TUE MAY 26TH. && .AVIATION.../12Z ISSUANCE/ ISOLATED SHOWERS WILL OCCUR THROUGH 16Z WITH A LITTLE BETTER COVERAGE OVER THE NORTH. AREAS OF MVFR CONDITIONS WILL OCCUR THROUGH 16Z. AFTER 16Z...SHOWERS AND ISOLATED THUNDERSTORMS WILL REDEVELOP OVER THE REGION. SHOWERS WILL DECREASE AFTER 03Z. THERE WILL BE AREAS OF MVFR CONDITIONS DUE TO LOW CIGS THROUGH 06Z MONDAY. EXPECT FREQUENT MOUNTAIN OBSCURATION THROUGH THE DAY INTO THE EVENING AS RAIN AND SNOW WILL OCCUR IN MOST MOUNTAINS. && .FIRE WEATHER... FIRE DANGER RELATIVELY LOW INTO THE MIDDLE OF THE WEEK AS SEASONAL TO COOL AND RELATIVELY MOIST CONDITIONS PERSIST. HOWEVER...IT WILL BE UNSTABLE AGAIN TODAY IN THE SOUTH AND WEST...OFFERING UP CHANCES FOR MORE THUNDERSTORMS AND ASSOCIATED LIGHTNING. SNOWS IS LIKELY TO RETURN TO THE HIGHER ELEVATIONS AGAIN THIS WEEKEND WITH SNOW LEVELS LOWERING TO AROUND 7000 FEET AT TIMES. AFTER A SHORT BREAK SUNDAY NIGHT...MORE SHOWERS ARE POSSIBLE WEST OF THE DIVIDE FOR MONDAY WITH A WETTING RAIN A DECENT POSSIBILITY FOR MANY AREAS ON TUESDAY. && .RIW WATCHES/WARNINGS/ADVISORIES... NONE. && SHORT TERM...HATTINGS LONG TERM...AEM AVIATION...AR FIRE WEATHER...HATTINGS
HAZARDOUS WEATHER OUTLOOK NATIONAL WEATHER SERVICE RIVERTON WY 500 AM MDT SUN MAY 17 2015 WYZ001>020-022>030-181100- ABSAROKA MOUNTAINS-BIGHORN MOUNTAINS SOUTHEAST- BIGHORN MOUNTAINS WEST-CASPER MOUNTAIN-CODY FOOTHILLS- EAST SWEETWATER COUNTY-FLAMING GORGE- GREEN MOUNTAINS AND RATTLESNAKE RANGE-JACKSON HOLE-LANDER FOOTHILLS- NATRONA COUNTY LOWER ELEVATIONS-NORTH BIG HORN BASIN- NORTHEAST JOHNSON COUNTY-OWL CREEK AND BRIDGER MOUNTAINS- ROCK SPRINGS AND GREEN RIVER-SALT RIVER AND WYOMING RANGES- SOUTH LINCOLN COUNTY-SOUTHEAST BIG HORN BASIN- SOUTHEAST JOHNSON COUNTY-SOUTHWEST BIG HORN BASIN-STAR VALLEY- TETON AND GROS VENTRE MOUNTAINS-UPPER GREEN RIVER BASIN- UPPER GREEN RIVER BASIN FOOTHILLS-UPPER WIND RIVER BASIN- WIND RIVER BASIN-WIND RIVER MOUNTAINS EAST-WIND RIVER MOUNTAINS WEST- YELLOWSTONE NATIONAL PARK- 500 AM MDT SUN MAY 17 2015 THIS HAZARDOUS WEATHER OUTLOOK IS FOR WESTERN AND CENTRAL WYOMING. .DAY ONE...TODAY AND TONIGHT ISOLATED TO WIDELY SCATTERED MAINLY AFTERNOON AND EVENING THUNDERSTORMS. SNOWFALL IN THE NORTHERN MOUNTAINS. .DAYS TWO THROUGH SEVEN...MONDAY THROUGH SATURDAY MONDAY...ISOLATED TO SCATTERED THUNDERSTORMS...MAINLY OVER THE WEST AND SOUTHWEST. TUESDAY AND WEDNESDAY...ANOTHER STORM SYSTEM WILL LIKELY BRING INCREASING SHOWERS AND ISOLATED THUNDERSTORMS ACROSS THE AREA TUESDAY ...AND CONTINUING THROUGH WEDNESDAY. SNOW LEVELS WILL BE MOSTLY BETWEEN 7000 AND 8000 FEET WITH SEVERAL INCHES OF SNOW POSSIBLE ON MOUNTAIN PASSES. THURSDAY THROUGH SATURDAY...ISOLATED TO SCATTERED AFTERNOON AND EVENING THUNDERSTORMS. .SPOTTER INFORMATION STATEMENT... SPOTTERS ARE URGED TO REPORT STRONG WIND GUSTS...HAIL...AS WELL AS HEAVY RAINFALL OVER A HALF AN INCH. THANK YOU. TEAM RIVERTON
The national radar mosaic for the moment the first event began.
1 avalanche. Local standard time, as filed.
As the offices recorded each death: direct deaths were caused by the weather itself, indirect ones by something it set in motion.
| Event | Date | Age | Sex | Where | Kind |
|---|---|---|---|---|---|
| Avalanche, Teton & Gros Ventre Mountains | 2015-05-17 | 39 | Male | Outside/Open Areas | Direct |
| Avalanche, Teton & Gros Ventre Mountains | 2015-05-17 | 42 | Male | Outside/Open Areas | Direct |
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Wyoming in 2015Every state in 2015This day in weather historyWarnings in Wyoming, May 2015
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: 567103.