CAIC: Full Report From Avalanche That Killed a Snowmobiler on Rollins Pass, CO

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Figure 6: An image of the avalanche taken on February 16, after additional snowfall and drifting. The red circle indicates where the avalanche partially buried Rider 1. Image courtesy GCSAR.

On Sunday 14th February 2021, a snowmobiler was caught and killed in an avalanche west of Rollins Pass, CO. The avalanche occurred on an east-facing, above treeline slope of Mount Epworth. When the avalanche stopped, the snowmobiler was buried underneath his sled on Pumphouse Lake.

Below is the full report from the CAIC:

Avalanche Details

  • Location: Pumphouse Lake, southwest of Rollins Pass
  • State: Colorado
  • Date: 2021/02/14
  • Time: Unknown
  • Summary Description: 1 snowmobiler caught, partially buried-critical, and killed
  • Primary Activity: Snowmobiler
  • Primary Travel Mode: Snowmobile
  • Location Setting: Backcountry


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


  • Type: HS
  • Trigger: AM – Snowmobile
  • Trigger (subcode): u – An unintentional release
  • Size – Relative to Path: R3
  • Size – Destructive Force: D2
  • Sliding Surface: G – At Ground/Ice/Firm


  • Slope Aspect: E
  • Site Elevation: 11500 ft
  • Slope Angle: 35 °
  • Slope Characteristic: —

Avalanche Comments

This was a hard slab avalanche unintentionally triggered by a snowmobile. It was medium-sized relative to the avalanche path and produced enough destructive force to bury, injure, or kill a person. The avalanche broke two to four feet deep, into old snow layers at the ground (HS-AMu-R3D2-G). The snowmobiler was caught on an east-facing slope above treeline, where the avalanche ran about 200 vertical feet onto Pumphouse Lake. The avalanche crown continued around a shoulder of Mount Epworth and onto a southeast-facing slope where the avalanche ran about 300 vertical feet. The entire crown face spanned over 2000 feet. Investigators used images taken by Grand County Search and Rescue on February 14 and 16 to estimate the avalanche dimensions.

Backcountry Avalanche Forecast

The backcountry avalanche forecast hazard rating for the Front Range was CONSIDERABLE (Level 3) at all elevations with large to very large Persistent Slabs likely on north through east and southeast aspects. The avalanche forecast summary for the Front Range on February 14 read:

You can trigger large, broad-breaking, far-running avalanches on many slopes, particularly those with signs of recent wind-loading. The most dangerous slopes face north through east to southeast, where recent winds have built fresh slabs up to 3 feet deep. An avalanche that starts in the recent storm snow will most likely break down into layers of old weak snow below. Avoid travel on or below slopes steeper than about 30 degrees.

A Special Avalanche Advisory was in effect from February 12 to 15. On February 14 the advisory read:

A Special Avalanche Advisory is in effect for the mountains of Colorado through Monday, February 15. Avalanche conditions are unusual. Backcountry travelers can trigger avalanches that may break very wide and run the full length of the avalanche path. Your normal routes and safety habits may not keep you out of a dangerous avalanche. Backcountry travelers need to take extra precautions this weekend. Check current conditions for the area you plan to travel. Adjust your plan for the day to fit the current avalanche conditions.

Weather Summary

Below-average snowfall and infrequent storms characterized the winter through January in northern Colorado. At the Fool Creek SNOTEL site, at an elevation of 11,150 feet and 10 miles west of the accident site, the February 1 snow-water equivalent (SWE) was 8.8 inches, ranking in the lowest third of percentiles for season-to-date snowfall since 2012.

A period of stormy weather started in early February. From February 4 to 6, Winter Park Ski Area, approximately 5 miles west of the accident site, reported 26 inches of snow. Dry weather and strong west winds occurred for the next three days. From February 6 to 9, the Bottle Peak weather station, at 11,200 feet and approximately 13 miles west of the accident site, recorded sustained west winds near 50 miles per hour with frequent higher gusts. More snow fell in the days prior to the accident, with 15 inches of snowfall at Winter Park Ski Area from February 10 to 14.

These storms significantly increased the depth of the snowpack. Snow-water equivalent at the Fool Creek SNOTEL site increased from 9.0 to 11.2 inches from February 4 to 14, an increase of nearly 25%.

Light snow continued into the morning of the accident. Temperatures were cold, with a high temperature of 13 F at the Bottle Peak weather station midmorning, and dropping into the single digits in the afternoon.

Snowpack Summary

Avalanche observations in the Front Range zone in the days before the accident indicate a weak snowpack producing large natural avalanches. From February 4 to 13, forty-one avalanches were reported in the Front Range zone, including ten large natural avalanches (size D2 or greater) on east or southeast-facing slopes near and above the treeline. Winds drifted significant amounts of snow onto these slopes during this period. Poor visibility and safety concerns in the hours and days following the accident did not allow investigators to examine the fatal avalanche in detail.

Events Leading to the Avalanche

Rider 1, a 58-year-old man, and Rider 2, his 18-year-old son, left the Lakota Trailhead for a day of snowmobiling. The two eventually rode into Pumphouse Lake. They high marked the short, steep east-facing slope above the lake several times. Rider 1 headed up for the third or fourth climb on the slope.

Accident Summary

Instead of turning downhill from his highpoint, Rider 1 sidehilled. The avalanche released. Rider 2 moved out of the way and was not caught.

Rescue Summary

When the avalanche stopped, Rider 1’s snowmobile was partially buried in the avalanche debris on the lake. It was pointing away from the slope, near the toe of the debris. There was no sign of Rider 1.

Rider 2 rode over to the buried sled and saw Rider 1’s boot in the snow. He started digging. Rider 1 was buried face-down, with his head under about one foot of avalanche debris. His torso was wedged between the track and tunnel, perpendicular to the sled. The avalanche or impact of the snowmobile broke the lake ice and Rider 1 was pinned in a slushy mix of avalanche debris and water. Rider 2 was unable to free his father from the snowmobile and used the shovel to prop his head out of the water. Rider 1 was initially conscious, but eventually lost consciousness and stopped breathing.

Rider 2 had to ride away from the lake to find cell reception. He called 911 at 1:39 PM. Grand County Search and Rescue (GCSAR) was paged out. The weather prevented helicopters from flying, though a Colorado Rapid Avalanche Deployment team was on standby at Winter Park.

Rider 3 was a member of Grand County Search and Rescue. He was unloading his snowmobile at the Lakota trailhead when he received the page. He acted as a hasty rescue team and rode into the accident site.

Rider 3 followed two snowmobile tracks into Pumphouse Lake and arrived at 2:06 PM. Rider 3 was able to pull Rider 1 free and began CPR. The second wave of GCSAR volunteers, including a physician, arrived about five to ten minutes later and began advanced life support. Rider 1 did not respond to resuscitation efforts.

Rescuers brought Rider 2 to the trailhead. He had lost a boot and glove in the rescue and received medical treatment for hypothermia. Rescuers later transported Rider 1 to authorities at the trailhead.


All of the fatal avalanche accidents we investigate are tragic events. We do our best to describe each one to help the people involved and the community as a whole better understand factors that may have contributed to the outcome. We offer these comments in the hope that they will help people avoid future avalanche accidents.

Based on Rider 1’s burial position and injuries, rescuers believe Rider 1 was thrown forward over his sled when he hit the abrupt slope transition at the lake. The spinning track caught and pinned him against the tunnel.

When we think about avalanche rescue it can be easy to focus on locating and excavating avalanche victims. Those skills are unique to avalanche rescues. Once located, an avalanche victim may become a patient and additional skills are required. Injuries need to be assessed and stabilized. The patient needs to be protected from cold and exposure. Evacuation from the backcountry can take a significant amount of time.

Rider 2 was able to locate and excavate Rider 1 while he was conscious, despite neither having avalanche transceivers. Rider 1’s injuries were not immediately life-ending, but he slowly asphyxiated pinned under the snowmobile. Even if GCSAR members had arrived while Rider 1 was breathing, it would have been a protracted and slow rescue effort to get him to ambulance care.

This was the third avalanche fatality in the Front Range complicated by lakes. In January 2016, a climber was caught in an avalanche on St Marys Lake, about 6.5 miles south of Pumphouse Lake. The avalanche broke the lake ice, and the climber’s legs were partially submerged. In November 2001, two backcountry skiers were caught in an avalanche that shattered the ice on Yankee Doodle Lake, about 1.5 miles east of Pumphouse Lake. The survivor was carried into the middle of the lake and swam through about 200 feet of broken ice to reach the shore.

The Grand County Sheriff’s Office and Grand County Search and Rescue members were instrumental in compiling this report.



Figure 1: A map of the Rollins Pass area. The accident site is marked by the red box.
Figure 2: A Google Earth image with the approximate extent of the avalanche outlined in red. Investigators used images taken on February 14 and 16 and provided by GCSAR members to estimate avalanche dimensions.
Figure 3: A topographic map of the accident site. Slope angles are shaded in Caltopo fixed bins (27-29 deg in yellow, 30-31 deg in light orange, 32-34 deg in orange, 35-45 deg in red, 46-50 deg in purple). The approximate boundaries of the avalanche are marked by the red polygon. Investigators used images taken on February 14 and 16 and provided by GCSAR members to estimate avalanche dimensions.
Figure 4: Looking up the avalanche from near Rider 1’s burial location. Image courtesy GCSAR.
Figure 5: GCSAR members working to excavate Rider 1’s sled from the avalanche debris. Image courtesy GCSAR.
Figure 6: An image of the avalanche taken on February 16, after additional snowfall and drifting. The red circle indicates where the avalanche partially buried Rider 1. Image courtesy GCSAR.
Figure 6: An image of the avalanche taken on February 16, after additional snowfall and drifting. The red circle indicates where the avalanche partially buried Rider 1. Image courtesy GCSAR.

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