Mammoth Mountain - Climax In-Bounds Avalanche March 3

AVALANCHE OBSERVATION
Mammoth Mountain - Climax

Drainage:

Submission Info
Forecaster
Sunday, March 4, 2018 - 10:00am
Red Flags: 
Recent loading by new snow, wind, or rain
Avalanche Type: 
Dry
Slab
Slope: 
35degrees
Trigger type: 
Other - explain below
Crown Height: 
7 ft
Aspect: 
Northeast
Weak Layer: 
Old Snow
Avalanche Width: 
1 030ft.
Terrain: 
Above Treeline
Elevation: 
10 940ft.
Bed Surface: 
Old Snow
Avalanche Length: 
4 600ft.
Number of partial burials: 
More than 5
Number of full burials: 
0
More detailed information about the avalanche: 

Official report from Mammoth Mountain:

At approximately 10:00am, 2 Ski Patrollers deployed two 2lb explosive hand charges onto the Climax ski run. The 105mm Howitzer had been fired earlier in the morning, with the closest shot being below the Upper Dry Creek chutes, in the vicinity of Balls to the Wall. It is believed that one of the charges may have triggered the avalanche. The avalanche followed the Dry Creek drainage towards the bottom of Chair 5. Climax and Dry Creek were closed to the public at the time. The debris (largely a powder cloud at this point) traveled approximately 100m further than the bottom of Chair 5. The avalanche was simultaneously reported by guests riding Chair 10, by two Lift Maintenance mechanics who were at the bottom of Chair 5, and by two on duty Ski Patrollers who were working nearby. All employees were able to quickly free themselves and respond to each other and nearby guests.

Mountain Operations and Ski Patrol immediately initiated emergency response protocols, including establishing Incident Command and Site Command. The ski area was closed to allow focus on the response. Additional Ski Patrollers with rescue gear were on scene within minutes. Ski Patrol led a 6-hour search, which included avalanche transceivers, 3 RECCO receivers, 4 avalanche rescue dogs, spot probing likely catchment areas, and rotating column search probe lines of 10 persons directed by Ski Patrol. No additional people were found. All missing person reports were fully investigated and resolved. The search was called off at approximately 4:30pm. Nearly 200 employees, first responders, and guests contributed to the on-hill efforts.

 

ESAC added comments:  From the crown profile, it was determined that this avalanche failed within the old snow in a weak facet layer under skier / rider compacted snow.  See attached photo and crown profile.

Avalanche Photos: 
Snowpit or crown profile photo or graph: 
37° 37' 52.8456" N, 119° 1' 58.5012" W

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