Avalanche Observation - Lost Johnny, Swan Range

Location Name: 
Avalanche Observation - Lost Johnny, Swan Range
Swan Range - East Side (Hungry Horse Reservoir access)
Date and time of avalanche (best estimate if unknown): 
Sat, 02/04/2017 - 16:30
Location Map: 

Red Flags: 
Recent avalanche activity
Whumphing noises, shooting cracks, or collapsing
Recent loading by new snow, wind, or rain
Obvious avalanche path

Observation made by: Public
Avalanche Observations
Avalanche Type: 
Trigger type: 
Weak Layer: 
Old snow
Below Treeline
5 000ft.
Bed Surface: 
Old Snow
Number of people caught: 
Number of partial burials: 
Number of full burials: 
More detailed information about the avalanche: 

The following information was provided to the Flathead Avalanche Center by a member of the party involved in this avalanche incident. We are grateful to these snowmobilers for sharing this information as it helps everyone learn, and are glad the incident resulted in no injuries.

On Saturday, February 4, 2017, a party of 5 experienced snowmobilers departed the parking lot at Hungry Horse Dam at approximately 10:30 a.m. and rode along the west side reservoir road to Lost Johnny Creek. They rode up this drainage on the summer road (typical winter approach) to the end of the summer road. The group of 5 riders then rode into the area locally known as "Pinball". The riders spent the entire day riding in this area. One rider mentioned that there was substantial wind loading above 6000 feet, and the riders intentionally avoided that terrain. The riders observed very small slab releases as wide as the length of a snowmobile on very small test slopes while sidehilling across these slopes. 

Around 4:30 p.m. the riders departed the Pinball area and began riding back down the Lost Johnny drainage/road the same way they rode in.  This road crosses under (or through the runout zone of) several major avalanche paths. Approximately 200 meters (650 feet) from the upper end of the Lost Johnny road Rider 1 observed snow moving down the slope above him and avalanche debris crossing the road. He stopped his snowmobile and began running back toward the direction he came and toward Rider 2 who was behind him.  He then observed the avalanche crossing between Rider 2 and Rider 3 (who was behind Rider 2). At this point, the avalanche caught Riders 4 and 5 (who were both behind Rider 3). Rider 4 was partially buried with his head facing downhill, and Rider 5 was fully buried. Rider 4 was able to extract himself while Rider 3 began a transceiver search for Rider 5. He pinpointed Rider 5 within 2-3 minutes and began digging. Rider 4 assisted him with the search and digging once free from the debris, and Riders 1 and 2 also assisted. They found Rider 5 unresponsive when they immediately reached him, but he became responsive instantly after digging him out. Riders 4 and 5 were wearing and deployed their airbags during the avalanche.

Rider 1 observed the crown approximately 60 m (200 feet) above their location. He estimated it to be about 2 feet deep and suspected it failed on the January 19 ice crust. He suspects this because they found this crust at this depth throughout the day. 

At this point, all riders were concerned about potential residual hazard above them, and placed themselves in relatively safe locations while Rider 4 used an In-Reach satellite communicator to reach Search and Rescue. Air assistance was unavailable due to stormy weather. Two snowmobiles were fully buried, and the riders decided that traveling underneath the remaining avalanche paths back down the drainage along the originally planned exit was too hazardous. They decided to walk downhill toward the creek farther away from the runout zone.  After deliberating about their exit options they eventually hiked approximately 5 hours along the creek in waist deep snow 1.5-2 miles where search and rescue were waiting (away from the runout zones of the avalanche paths). North Valley Search and Rescue personnel based out of Columbia Falls transported them back to their vehicles at the Hungry Horse Dam parking lot. 

While hiking out along the creek the riders experienced whumpfing (collapsing) of the snowpack numerous times and also observed widespread shooting cracks (all signs of instability). They also noticed 1-2 foot small avalanches on some of the cutbanks along the reservoir road on the ride out with Search and Rescue. It is difficult to truly know if this avalanche was a natural avalanche, or if simply by riding underneath the slope the riders were able to trigger the avalanche from the runout zone. The riders mentioned that there were other parties riding in the area, and they were the last party to exit the area that day.

We are grateful that no one was injured during this incident, and commend the riders for their swift rescue of the fully buried rider. Due to the continued storm and rising avalanche hazard expected over the next 24-36 hours, FAC will not visit the site.  Stay updated with avalanche information at flatheadavalanche.org.

Forecaster's Note: This current storm has caused very dangerous avalanche conditions. Since this is the first real storm after several weeks of dry conditions we all have powder fever, but now is not the time to ski or ride in avalanche terrain. Most avalanche accidents occur during or immediately following a storm cycle. Allow the snowpack a few days to adjust to the load being deposited onto it. Travel in avalanche terrain is not recommended. This includes runout zones and all terrain connected to avalanche terrain. 

Avalanche Photos: 
Weather Observations
Blowing Snow: 
Cloud Cover: 
100% of the sky covered by clouds
Wind Speed: 
Moderate (Small trees sway)
Accumulation rate: 
Less than 1 in. per hour