CAIC: Colorado Avalanche Information Center

2013/03/17 - Colorado - Ypsilon Mountain, Rocky Mountain National Park

Published 2013/04/16 by Brian Lazar - CAIC

Avalanche Details

  • Location: Ypsilon Mountain, Rocky Mountain National Park
  • State: Colorado
  • Date: 2013/03/17
  • Time: 12:00 AM (Estimated)
  • Summary Description: 2 climbers caught, 2 injured, 1 killed
  • Primary Activity: Climber
  • Primary Travel Mode: Foot
  • Location Setting: Backcountry


  • Caught: 2
  • Partially Buried, Non-Critical: 0
  • Partially Buried, Critical: 0
  • Fully Buried: 0
  • Injured: 1
  • Killed: 1


  • Type: SS
  • Trigger: Unknown
  • Trigger (subcode): --
  • Size - Relative to Path: R2
  • Size - Destructive Force: D1.5
  • Sliding Surface: I - New/Old Interface


  • Slope Aspect: NE
  • Site Elevation: 13100 ft
  • Slope Angle: 45 °
  • Slope Characteristic: Gully/Couloir

Avalanche Comments

The avalanche was a soft slab, either triggered naturally from wind loading of new snow or possibly from a descending climber lower in the couloir . The avalanche was small relative to the avalanche path, just large enough to injure and potentially bury a person. The avalanche was confined to recently wind-drifted snow and broke at the new-old snow interface (SS-Nu-R2/D1.5-I).

Weather Summary

The winter of 2012-13 produced below average snowfall in Rocky Mountain National Park. Strong winds commonly buffet this area, and this season was no exception. March 15-16 were warm days with daytime highs reaching into the mid to upper 30s in the alpine. Between the evenings of March 16th and 17th, several inches of snow fell and westerly winds increased into the 15 to 25 mph range with gusts into the 50s. Temperatures cooled gradually on the 16th and dropped off precipitously during afternoon of the 17th. 

Snowpack Summary

The snowpack throughout Rocky Mountain National Park was shallow, highly variable, and highly wind-affected. The average snowpack depth was around 100 cm, but some areas were blown completely free of snow, while heavily wind-loaded areas held drifts of 300cm deep or more. Many of the steeper couloirs held wind-drifted snow over 2 meters deep. The snowpack structure in these features held hard (P+) thick slabs throughout the mid and lower snowpack, with thin (30 to 60 cm thick) soft wind slabs on the surface.

Events Leading to the Avalanche

A party of two (Climber 1 and Climber 2) departed from the Lawn Lakes trailhead at 3:15AM on the morning of March 16th with intent of climbing Ypsilon Mountain (13,514 ft) via the Blitzen Ridge route and descending via the Donner Ridge to the south. Blitzen Ridge is a technical mountaineering route (Grade II, 5.4 to 5.7) with numerous sections of 5th class climbing.

The party arrived at the beginning of the crux technical section called the Four Aces at approximately 9:45AM. They spent the rest of the day on the 16th negotiating this technical section in winter conditions, and finished the 4th Ace around 7:00PM. Given that they were moving more slowly than anticipated and with darkness imminent, they discussed descending a northeast-facing couloir just west of the 4th Ace into the Fay Lakes drainage. They elected not to do so due to concern about the avalanche conditions and wind-loading in the couloir, and instead opted to continue towards the summit of Ypsilon Mountain and less technical terrain.

They continued their ascent at 7:30PM and climbed through the night of March 16th, but got off route due to darkness and veered into more technical terrain to the north of Blitzen Ridge proper which further slowed their progress.  By dawn of March 17th, they were still making their way towards the summit on technical terrain towards the Northeast Couloir north of Blitzen Ridge. They crossed the Northeast Couloir below the upper wind-loaded slopes, and climbed to a notch in the ridge about 200 vertical feet below the summit of Ypsilon Mountain around 5PM.

At their high point at the rock notch at 13,300 feet, Climber 1 was exhibiting obvious signs of fatigue and mild hypothermia. They discussed that avalanche conditions were a concern but their predicament led them to decide that descending the NE Couloir was the best descent option at the time. They decided to retreat via that route to the north and into the Fay Lakes drainage. They had a 60m rope they were using to climb, but with only a light rack of alpine gear, they could not rappel the entire expanse of rocky technical terrain. The party was roped together using all 60m of rope when they entered the Northeast Couloir. They were simul-climbing down the right side of the couloir with Climber 2 in the lead and placing rock protection into adjacent rock face.


Accident Summary

The party was approximately half way down the narrow portion the couloir when a soft wind slab released above the Climber 1. It is unclear whether Climber 1 triggered the slide from below or if it released naturally from wind-loading, but given the start zone and the position of the climbers at the time of the avalanche, the trigger was most likely wind-loading. There were two pieces of rock protection in place (a nut and 0.75 Camalot) at the time of the avalanche. Both climbers took a very violent fall of approximately 100 feet hitting rocks and ice on the way down, at which point the Camalot arrested their fall with Climber 1 coming to rest about 30 feet above Climber 2. The nut pulled loose and was dangling from the rope after the avalanche. The avalanche debris mostly ran by the climbers but it did cement the rope into place and it was not retrievable.Climber 1 indicated that he was not injured and OK, but the coroner's report indicate minor injuries. Climber 2 sustained broken ribs, a torn MCL, a broken coccyx, and damage to her wrist ligaments.

At this point, the two climbers descended the lower portion of the couloir with Climber 1 walking in crampons and Climber 2 walking in crampons until she changed into snowshoes on the lower snow ramp.  Darkness had descended, and they walked approximately 1/4 mile from the bottom of the couloir and Climber 2 changed back to crampons to descend two small ice steps. They walked most of the way down a snow slope before Climber 1 was no longer able to travel on. Climber 1's level of consciousness began to rapidly deteriorate during this 1/4 mile walk. Climber 2 positioned Climber 1 in as sheltered and as comfortable position as possible, and then both of them spent the night of March 17th on the snow slope. Climber 2 reported that Climber 1 became unresponsive around 8:30 PM.

Rescue Summary

Climber 2 departed the scene at dawn on the morning of March 18th, and after walking a couple miles encountered National Park search and rescue members just above and northeast of Ypsilon Lake. Search and rescue provided emergency medical care and facilitated her transport back to the trailhead. National Park search and rescue and a CAIC forecaster went in to locate Climber 1 on the morning of March 19th, and found him on the snow slope beneath the ice steps. The official cause of death as determined by the coroner was hypothermia.

Climber 2's survival is impressive and improbable given the length of time exposed to brutal weather conditions and the extent of her injuries.


This was a complicated mountaineering accident with many contributing factors.  The avalanche was a contributing factor, but was not solely responsible for the fatal outcome.