2013-2014 Incidents

2/25/2014 – Avalanche Incident – Canyon Creek, Whitefish Range

2/22/2014 – Avalanche Incident – McGinnis Creek (Depuy Creek ), Whitefish Range

2/22/2014 – Avalanche Incident (Fatality) – Spar Peak, Cabinet Range (Kootenai National Forest advisory area)

2/15/2014 – Avalanche Incident – Canyon Creek, Whitefish Range

12/14/2013 – Avalanche Incident – Picnic Notch, Noisy Basin, Swan Range

12/8/13 – Avalanche Incident – Noisy Basin, Swan Range

 

2/25/2014 – Avalanche Incident – Canyon Creek, Whitefish Range

 Updated Information of Avalanche Incident in Canyon Creek  – 2/25/2014

 Avalanche Incident Report
Canyon Creek, Whitefish Range, MT
Date of Avalanche: 25 February 2014
Date of Investigation: 26 February 2014

INCIDENT SYNOPSIS (provided by a member of the party involved)

At 15:00 on 2/25/14 I was part of a three person snowboarding group that was caught in an avalanche in the Canyon Creek area in the Whitefish Range. At 14:00 we hiked Flower Point and dug a pit on a ENE Aspect, 35 degree slope. We found a weak layer about 50cm down from the surface. Our stability tests showed CT24Q3, ECTP22Q3. We rode the ridge out toward Banana Chutes and dropped into the Canyon approximately 300yds skiers right of Banana Chutes. We reached the bottom, quickly rechecked our beacons and began hiking out back to chair 7. At 15:00, just as we were reaching the top of the hike out, we heard a boom and an avalanche descended on us from the opposite face we rode (Skookoleel ridge, fiberglass hill). The avalanche missed me by about 20 feet but caught the other two members of my party. One person was swept off his feet but was able to swim out of it and was not buried. The second person was also swept off his feet and was buried with only his head and one arm sticking out. We were able to quickly locate and dig this person out. No one in our group was seriously injured and we were all wearing beacons and had shovels and probes. 

SS-NO-R3-D2.5-O (Comments on classification: After investigating the avalanche and based on statement from those involved, we decided to classify the avalanche as a natural trigger. All evidence suggests it was a natural avalanche. We were unable to find any tracks above the crown. We were on the ridge on the opposite side of the canyon just prior to the avalanche release, but did not witness it. We observed a small loose sluff on the slope prior to the slab release. It is possible that a small sluff from the rocks on the slope could have triggered the slide, but aside from the sluff we observed that already existed we observed no other evidence of sluffing.)

This was the second avalanche incident involving partial burials in Canyon Creek within 10 days.

Widest part from flank to flank: 233 m (766 ft.)
Crown depth: Avg. 70 cm (28 in.), Maximum 100 cm (39 in.)
Vertical fall: 183 m (600 ft.)
Ground distance: 255 m (840 ft.)
Debris pile width (max.): 260 m (850 ft.)
Debris depth: 160-200 cm
Failure layer: Faceted snow (FC) above melt-freeze (MF) crust from late January.
Slope angle at crown: 39°
HS (height of snow) at crown = 165 -218 cm (65 – 79 in.)
Aspect at portion of crown investigated: 209°

Thanks to Craig Moore (GlacierWorld.com) for providing overview images of the incident site. Please contact Craig for permission to use those images. All other images are courtesy of Flathead Avalanche Center (see images at end of report).

WEATHER AND SNOWPACK

Beginning February 1, 2014, an arctic air mass parked itself over the region until around February 10, 2014. Prior to this a melt-freeze crust formed on sunny aspects throughout the advisory area. Small accumulations of snow occurred periodically and fell on this crust. During the cold air outbreak, the surface and near surface snow became weak and faceted causing weak layers to form on top of the melt freeze crust. The next notable precipitation commenced the afternoon of February 10, 2014 and snow accumulated incrementally through February 22, 2014. During that arctic outbreak mountain temperatures reached below -20 °F. When the cold air mass exited the region, temperatures rose with new snowfall throughout the advisory area. A special avalanche bulletin was issued on Thursday, February 20, 2014 to advise backcountry travelers of elevated avalanche danger through the weekend.

The most recent avalanche advisory prior to the incident was issued Sunday, February 23, 2014. The bottom line read:

“For today the avalanche hazard is rated as CONSIDERABLE. Human triggered avalanches are LIKELY and natural avalanches are possible. Dangerous avalanche conditions still exist. The late January crust/facet layer still exists 2-4 feet deep and poses a potentially dangerous persistent slab problem. Careful snow pack evaluation, cautious route finding, and conservative decision making remain essential. Staying out of the runout zones, especially terrain traps, is important.

Note: We are in a period of tricky and potentially dangerous avalanche conditions. Many of us are powder starved and waiting to get into the backcountry. We need to ease back into the backcountry to see what is in store. Approach slopes today with caution and treat them as suspect until you can prove otherwise. Given the uncertain nature of persistent slab, they deserve a wide margin of safety.”

Another cold air mass infiltrated the region 48 hours prior to the avalanche causing mountain temperatures to reach  -13 °F. Clear skies, intense solar input, and rising temperatures (above freezing in some locations) occurred on the day of the avalanche (February 25).  The closest reliable mountain weather stations that provides hourly data is Hand Creek SNOTEL (elev. 5035 ft. and ~40 km to the southwest of the incident site) and Stahl Peak SNOTEL (elev6030 ft. and ~60 km to the northwest). 

HandCkAirTemp HandCkSnoDepthSWE StahlPkAirTemp StahlPkSnoDepthSWE

AVALANCHE

FAC staff received a report of an avalanche in Canyon Creek around 4:00 p.m. from a member of the Whitefish Mountain Ski Patrol. FAC staff spoke with one of the individuals involved in the avalanche later that evening and he reported that all individuals involved were uninjured and safe. FAC staff visited the incident site the next day on Wednesday, February 26 and completed a fracture line profile on a southwest aspect (209 degrees) and found an approximately 70 – 100 cm (28 – 39 in.) slab sitting on a layer of faceted crystals over a 1 inch (3 cm) thick melt-freeze crust. The bed surface of the avalanche was the melt-freeze crust.

Stability tests on the crown: ECTP 28 Q1 (failure layer was the facets above the melt-freeze crust). This is the same snow structure (weak layer and bed surface) of two reported human triggered avalanches just three days prior. The snow profile of one of the incidents in nearby Depuy Creek shows the same structure. 

 

Crown profile

Crown profile. Depuy Creek avalanche 2/23/2014

 

 

 

 

 

 

 

 

 

 

Overview of crown of 2/25 Canyon Creek avalanche. 2/26/2014.

Overview of crown of 2/25 Canyon Creek avalanche. 2/26/2014.


Overview of crown of 2/25 Canyon Creek avalanche. 2/26/2014.

Overview of crown of 2/25 Canyon Creek avalanche. 2/26/2014.


Close up of crown of 2/25 Canyon Creek avalanche. 2/26/2014.

Close up of crown of 2/25 Canyon Creek avalanche. 2/26/2014.


Close up of crown of 2/25 Canyon Creek avalanche. 2/26/2014.

Close up of crown of 2/25 Canyon Creek avalanche. 2/26/2014.


Close up of crown of 2/25 Canyon Creek avalanche. 2/26/2014.

Close up of crown of 2/25 Canyon Creek avalanche. 2/26/2014.


Looking up at crown of 2/25 Canyon Creek avalanche. 2/26/2014.

Looking up at crown of 2/25 Canyon Creek avalanche. 2/26/2014.


Avalanche debris near a memorial tree where David Gogolak died in an avalanche in 2008. 2/26/2014.

Partial burial of individual was right near a memorial tree where a previous avalanche fatality occurred in 2008. 2/26/2014.


Snow height marked on tree of powder cloud of 2/25 Canyon Creek avalanche. 2/26/2014.

Snow height marked on tree of powder cloud of 2/25 Canyon Creek avalanche. 2/26/2014.


Looking down from crown at debris and road/snowmobile trail of 2/25 Canyon Creek avalanche. 2/26/2014.

Looking down from crown at debris and road/snowmobile trail of 2/25 Canyon Creek avalanche. 2/26/2014.


Western flank of 2/25 Canyon Creek avalanche. 2/26/2014.

Western flank of 2/25 Canyon Creek avalanche. 2/26/2014.


Skin track covered by debris of 2/25 Canyon Creek avalanche. 2/26/2014.

Skin track covered by debris of 2/25 Canyon Creek avalanche. 2/26/2014.


Debris on subsequently plowed road of 2/25 Canyon Creek avalanche. 2/26/2014.

Debris on subsequently plowed road of 2/25 Canyon Creek avalanche. 2/26/2014.

 

 20140225CanyonCkGE2 20140225CanyonCkGE1


 

COMMENTS

The staff at the Flathead Avalanche Center wish to extend our gratitude to those involved for providing their first-hand account of the events. This information helps all of us learn in the context of a real situation, and helps promote sound backcountry decision making.

SEARCH AND RESCUE

No search and rescue operations were initiated as the individuals involved were able to extricate themselves.

Direct any questions regarding this report to fac.admin@flatheadavalanche.org or 406.261.9873.

Report prepared by Erich Peitzsch of the Flathead Avalanche Center. Special thanks to Ted Steiner for assisting in the investigation.

REFERENCES

All formal notation and recording guidelines can be found in:
Greene, Ethan M., D. Atkins, K. Birkeland, K. Elder, C. Landry, B. Lazar, I. McCammon, M. Moore, D. Sharaf, C. Sterbenz, B. Tremper, and K. Williams, 2010. Snow, Weather, and Avalanches: Observational Guidelines for Avalanche Programs in the United States. American Avalanche Association, Pagosa Springs, CO: Second Printing Fall 2010, 152 pp.

 

 

 

 

 

 

 

 

 

 

 

 

 

2/22/2014 – Avalanche Incident – McGinnis Creek (Depuy Creek ), Whitefish Range

 

Updated Information of Avalanche Incident in Depuy Creek (formerly reported as McGinnis Creek) – 2/22/2014

 

Initially reported in McGinnis Creek, but avalanche technically occurred in nearby Depuy Creek and will be referred to as Depuy Creek avalanche hereafter.

Avalanche Incident Report
Depuy Creek, Whitefish Range, MT
Date of Avalanche: 22 February 2014
Date of Investigation: 23 February 2014

INCIDENT SYNOPSIS

On Saturday, February 22, 2014, a snowmobiler triggered an avalanche on a northeast facing (aspect 65 degrees) slope in the Depuy Creek drainage in the southern Whitefish Range.  We investigated the avalanche on February 23, 2014. The avalanche failed on a layer of weak, faceted snow sitting on top of a hard, melt-freeze crust about 95 cm (37 in.) from the surface. It was approximately 130 m (425 feet) wide, ran 166 m vertical (546 vertical feet) (from approximately 5556 feet to 5010 feet), and 362 m linear (1187 linear feet). Avalanche debris was approximately 2.75 m (9 feet) deep in a confined gully above an old logging road.

The alpha angle (toe of debris to the crown of the avalanche) was 31 degrees. The average slope angle at the crown was 37 degrees with a maximum slope angle of 41 degrees.

We received detailed information from the individual involved. One person was mostly buried with only his airbag visible to his companions, another individual remained on their sled and was only slightly buried.

The avalanche was classified: SS-AMu-D2.5-R4-I (This translates to a soft slab (SS) avalanche triggered unintentionally by a snowmobiler (AMu). The avalanche rates 2.5 out of 5 on the destructive scale (D2.5) which means it is on the high end of D2 on the scale and could bury, injure, or kill a person. It was large relative to the path (R4), and failed at the interface between the new and old snow (I).

 

 

WEATHER AND SNOWPACK

Weather data is from the Whitefish Mountain Resort Ski Patrol Weather Log at the summit of Big Mountain in the southern Whitefish Range which is located about 12.9 km (8 miles) southwest of the the incident site. The closest SNOTEL site is Flattop Mountain in Glacier National Park about 38 km (24 miles) to the northeast. This site showed the average snow water equivalent to be 112% of median, and the precipitation to be 101% of average.

Beginning February 1, 2014, an arctic air mass parked itself over the region until around February 10, 2014. Prior to this a melt-freeze crust formed on sunny aspects throughout the advisory area. Small accumulations of snow occurred periodically and fell on this crust. During the cold air outbreak, the surface and near surface snow became weak and faceted causing weak layers to form on top of the melt freeze crust. The next notable precipitation commenced the afternoon of February 10, 2014 and snow accumulated incrementally through February 22, 2014 (date of incident) (Figure 1). During that arctic outbreak mountain temperatures reached below -20 °F. When the cold air mass exited the region, temperatures rose with new snowfall throughout the advisory area (Figure 2) . This pattern created an upside down snowpack where heavier, dense snow fell on top of less dense, weaker snow. This new snow was accompanied by light to moderate winds according to Ski Patrol weather logs (Figure 3). On Sunday, February 16, 2014, an avalanche warning was issued for the Flathead Range and the warning remained in effect on February 17, 2014 and included the other ranges within the advisory area with a hazard rating of HIGH. Avalanche warnings for the entire advisory area were issued on each day thereafter until allowed to expire on Friday, February 21, 2014. A special avalanche bulletin was issued on Thursday, February 20, 2014 to advise backcountry travelers of elevated avalanche danger through the weekend.

20140222McGinnisCreekWxSnow

Figure 1: Snow Depth and Daily Snow at Summit (6,817 ft.), Big Mountain, Whitefish Range, from February 8, 2014 to February 22, 2014. The event took place on February 22, 2014.

 

Figure 3: Estimated Wind Speed and Direction at Summit (6,817 ft.), Big Mountain, Whitefish Range, from February 8, 2014 to February 22, 2014. The event took place on February 22, 2014.

Figure 3: Estimated Wind Speed and Direction at Summit (6,817 ft.), Big Mountain, Whitefish Range, from February 8, 2014 to February 22, 2014. The event took place on February 22, 2014.

 

 

 

 

 

 

 

 

20140222McGinnisCreekWxAT

Figure 2: Air Temperature at Summit (6,817 ft.), Big Mountain, Whitefish Range, from February 8, 2014 to February 22, 2014. The event took place on February 22, 2014.

 

 

 

Flathead Avalanche Center (FAC) staff were in nearby Kimmerly Basin and Canyon Creek on Thursday (2/20/2014) where they observed evidence of recent natural avalanche activity. They conducted a crown profile on a recent natural avalanche on a southeast aspect and found the failure to have occurred on a layer of weak faceted snow on top of the late January melt-freeze crust (profile). On Saturday (2/22/2014) FAC staff were in the Doris Creek drainage and found deep persistent slabs on multiple aspects and remnant storm slab instabilities.

Unstable conditions existed throughout the region and the avalanche hazard was rated as CONSIDERABLE in the Whitefish Range on the day of the incident. Other human triggered avalanches occurred on Saturday were reported that evening or Sunday. No natural activity was reported or observed in the Whitefish Range in the days leading up to this incident. The bottom line in the avalanche advisory for that day read:

“For today the avalanche hazard is rated as CONSIDERABLE. While natural avalanche activity has decreased human triggered avalanches are still likely, particularly on wind loaded slopes and slopes 35 degrees and steeper. Dangerous avalanche conditions still exist. The late January crust/facet layer still exists 2-4 feet deep and poses a potentially dangerous persistent slab problem. Careful snow pack evaluation, cautious route finding, and  conservative decision making remain essential. Staying out of the runout zones, especially terrain traps, is important.

Note: We are in a period of tricky and potentially dangerous avalanche conditions. Many of us are powder starved and waiting to get into the backcountry. We need to ease back into the backcountry to see what is in store. Approach slopes today with caution and treat them as suspect until you can prove otherwise or not. Many areas adjacent to our advisory area are currently dealing with a deep, persistent slab problem. There is still a lot of uncertainty about this persistent slab problem in our area until we receive more information/data.”

 

 

AVALANCHE

FAC staff received a report of a snowmobile triggered avalanche on the evening of Saturday, February 22, 2014 in McGinnis Creek in the Whitefish Range (Figure 4 and 5). Staff spoke with one of the individuals involved in the avalanche and received another report via email from a witness of the avalanche. Initial reports stated no one was injured and everyone involved made it out without further incident. FAC staff visited the incident site on Sunday, February 23 (the day after the accident), and completed a fracture line profile on a northeast aspect (65 degrees) and found an approximately 100 cm (39 in.) slab sitting on a layer of faceted crystals over a 1 inch (3 cm) thick melt-freeze crust (Figure 6 and 7). The bed surface of the avalanche was the melt-freeze crust at 100 cm (39 in.) below the surface.

Stability tests on the crown of the avalanche did not  initiate a fracture on the layer that the avalanche failed on.

Area overview

Figure 4: area overview of Depuy Creek avalanche

 

 

 

 

 

 

 

 

 

Depuy Creek area overview

Figure 5: area overview of Depuy Creek avalanche.

 

Crown profile

Figure 6: Crown profile. Depuy Creek avalanche 2/23/2014

 

 

 

 

 

 

 

 

Crown

Figure 7: Close up crown image. Depuy Creek 2/23/2014

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

The debris ran across a logging road in the Depuy Creek drainage. An individual that witnessed the avalanche initially reported the incident Saturday (2/22/2014) afternoon. We measured the debris in a confined gulley where the partial burial appeared to have occurred and found depths of up to 275 cm (108 inches). The total snow depth at the crown measured 261-274 cm (102-108 in.). The avalanche ran approximately 546 vertical feet, 1187 linear feet, and was about 425 feet wide at the widest extent of the crown (Figure 8 – 10).

Depuy Creek Avalanche close

Figure 8: Close up outline of Depuy Creek avalanche.

 

Crown line from bottom of run out

Figure 9: Looking up at crown line from bottom of run out. Depuy Creek 2/23/2014

 

 

 

 

 

 

 

 

Run out from highest point

Figure 10: Looking down from highest point of crown line. Depuy Creek 2/23/2014

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 On Saturday, February 22, 2013 six snowmobilers were traveling in the Depuy Creek drainage in the Whitefish Range. They departed from the parking lot at McGinnis Creek Road located off of the North Fork Road approximately 13 miles north of Columbia Falls, MT. The snowmobilers checked the advisory during the week prior to Saturday and knew the hazard was rated High throughout the week, but did not check the advisory that morning. They chose McGinnis Creek because, in their mind, it was a fairly safe place with less exposure and less high consequence terrain than other areas they considered. They thought they should stay away from steep, high consequence terrain that day.

Upon reaching an old logging road below the slope that was later triggered, one rider (Rider 1) decided to ascend the slope. Rider 1 had ascended the slope and was descending back down while two other riders (Rider 2 and 3) were off on the side of the slope when (Rider 1) triggered the avalanche. Rider 1 was knocked off of his machine, deployed his airbag (balloon), and was carried an estimated 150-200 yards downslope. Rider 1 came to a rest in a reclining position, almost fully buried with his helmet packed with snow. Only rider 1’s airbag was visible to his companions however he was able to wiggle himself free and extricate himself. Rider 2 stayed on his machine on the outer edge of the avalanche, was caught and carried downslope about 70 yards. Rider 2’s snowmobile was partially buried and he was only slightly buried while sitting on his sled. Rider 3 was able to get away from his machine and stay out of the avalanche. His machine was fully buried near the toe of the debris. The three other riders were sitting on the old logging road near the bottom of the slope. When they saw the slope begin to avalanche they all moved safely out of the path of the avalanche. All of those involved were uninjured. The party spent the next two and a half hours finding and extricating Rider 3’s snowmobile. They observed no natural avalanche activity that day, but did observe natural activity that had occurred the week prior. They observed no shooting cracks, collapsing or other signs of instability.

The group had advanced experience snowmobiling and were comfortable on most terrain. Rider 1 took an avalanche awareness course in the early 2000s, and another member of the party had taken a Level 1 course. Rider 1 thought the group handled the situation very well. Rider 1 feels like some of the lessons learned were that education is important and recognizing proper terrain for given conditions. He mentioned he had never seen a slide that large in this area, and was surprised by the potential.

  

COMMENTS

The staff at the Flathead Avalanche Center wish to extend our gratitude to Rider 1 for his willingness to share this important, detailed, and personal information. This information helps all of us learn in the context of a real situation, and helps promote sound backcountry decision making.

 

 

SEARCH AND RESCUE

No search and rescue operations were initiated as the individuals involved were able to extricate themselves.

Direct any questions regarding this report to fac.admin@flatheadavalanche.org or 406.261.9873.

Report prepared by Erich Peitzsch and Todd Hannan of the Flathead Avalanche Center. Special thanks to Snowmobile Ranger Lucas Stacy for assisting in the investigation.

REFERENCES

All formal notation and recording guidelines can be found in:
Greene, Ethan M., D. Atkins, K. Birkeland, K. Elder, C. Landry, B. Lazar, I. McCammon, M. Moore, D. Sharaf, C. Sterbenz, B. Tremper, and K. Williams, 2010. Snow, Weather, and Avalanches: Observational Guidelines for Avalanche Programs in the United States. American Avalanche Association, Pagosa Springs, CO: Second Printing Fall 2010, 152 pp.

 

 

 

 

2/22/2014 – Avalanche Incident (Fatality) – Spar Peak, Cabinet Range (Kootenai National Forest advisory area)

SPAR PEAK AVALANCHE INCIDENT REPORT

Idaho Panhandle National Forest, Montana

Date of Avalanche: 22 February 2014

Investigation Team:  Jon Jeresek with assistance from Erich Peitzsch and Seth Carbonari

Flathead Avalanche Center

 

Location:

Sandpoint Ranger District                                               East Fork Creek, West Cabinet Range

Idaho Panhandle National Forest – Region 1                                      Elevation 6,175 feet – 5,640 feet

Lincoln County, Montana                                                       Lat. 48’ 15’ 09”, Long. 116’ 0’ 23”

 

Summary:

-          49 Year old, Male Snowmobile Rider, Caught, Completely Buried, Fatality

-          47 Year old, Male Snowmobile Rider, Caught, Almost Completely Buried (face exposed), Uninjured

-          2 Snowmobiles buried, 1 recovered operational, 1 remains buried on site

 

Incident Synopsis: 

On Saturday, February 22, 2014, a group of four snowmobilers were playing in the trees in the headwaters of East Fork Creek, two air miles north of Spar Peak, Montana.  Around 1315, two members of the party were caught by an avalanche that released above them while the other two members of the party were not caught.  One fully buried rider was extracted, but tragically CPR efforts were unsuccessful.  The other nearly fully buried rider (only face exposed) was extracted without injuries and participated in rescue efforts.  One snowmobile was buried and remains on site, location unknown.  Another snowmobile was buried except for a ski loop sticking out of the snow and was extracted and used to return to the trailhead.  While CPR efforts were ongoing, one rider drove two miles to a site with known cell phone coverage to call 911.   The ALERT helicopter from Kalispell arrived on scene but could not find a safe landing spot and dropped a hand held radio to the party.  The snowmobile party told ALERT they had discontinued CPR and never had attained a pulse or any other response from the victim.  The Flathead County Sheriff’s Office Helicopter with hoist capabilities was ordered and successfully retrieved the victim.  The three remaining party members snowmobiled approximately 11 miles to the trailhead. 

The following information was developed from video taken by the Flathead County Sherriff’s Office Helicopter as it transferred people to/from the site and circled the avalanche area.  The avalanche crown measured approximately 1,200 feet across the top of a ridge that trends north to south and downward from 6,175 feet to 6,025 feet.  The south flank of the avalanche measured approximately 1,000 feet.  The north flank of the avalanche measured approximately 750 feet to the burial location at 5,685 feet elevation.  The avalanche occurred on an east aspect and involved mostly soft slab and loose snow material.  It is evident from the photographs that immediately below the ridgeline for a distance of 100’ – 150’ is a hard slab wind deposit that was also released (Figure 4).  Crown depths of this wind deposit vary from 30” to 50”.  Victims of this party were transported a very short distance due to their original location in the run out zone.  US classification of the avalanche is SS-AMr-R4/D3-I, which denotes a (SS) Soft Slab avalanche- (AMr) artificially triggered by snowmobile remotely-(R4)the avalanche was large relative to the path-(D3) the avalanche was large enough to bury and destroy a car, large truck, destroy a wood frame house, or break a few trees-(I) the avalanche released at the new snow/old snow interface.

Figure 1: Spar Peak Accident Location 15 miles SW of Troy, MT

Figure 1: Spar Peak Accident Location 15 miles SW of Troy, MT

Weather and Snowpack:  Weather information was collected from the Bear Mountain SNOTEL Station that is located approximately 5 miles NW of the accident site at 5400 feet. This site showed the average snow water equivalent to be 72% of median, and the precipitation to be 83% of average at the time of the accident. The entire Northern Panhandle Region was 90% of median for snow water equivalent and 74% of average precipitation at that time.

Beginning February 1, 2014, an arctic air mass dominated the region until around February 10, 2014. Prior to February 1, a melt freeze crust formed in many areas across the advisory area. Small accumulations of snow occurred periodically and fell on this crust. During the cold air outbreak, the surface and near surface snow became weak and faceted causing weak layers to form on top of the melt freeze crust. The next notable precipitation commenced the afternoon of February 10, 2014 and snow accumulated incrementally through February 22, 2014 (date of incident) (Figure 2). The snowpack increased by approximately 40 inches through that time period with a correlating 13 inch increase in Snow Water Equivalent.  During that arctic outbreak, mountain temperatures reached below -25 °C /-15°F(Figure 3). When the cold air mass exited the region, temperatures rose with new snowfall throughout the advisory area. This pattern created an upside down snowpack where heavier, dense snow fell on top of less dense, weaker snow. This new snow was accompanied by moderate to strong winds adding to the growth of cornices and wind pillows on the lee slopes.  On Friday, February 21, 2014, the avalanche advisory for the Kootenai National Forest was issued with a hazard rating of HIGH. The advisory stated “We have abundant soft snow available for wind transport.  Southwest winds Tuesday and Wednesday transported MUCH snow.  Wind slabs and pillows formed on northeast and east aspects near ridgetops.  These locations should be identified and avoided.”

Avalanche Specialists were not able to visit the accident site because of continued avalanche danger.  Observations were made in the area the days leading up to the accident.  Idaho Panhandle Avalanche Center staff were at nearby Moose Lake (8 miles NW of the accident site) on February 20, two days prior to the accident.  They identified the weak layers and crusts noted above, but found it took hard force to get those weak layers to shear, whereas they were able to get other weak layers to fail closer to the surface with moderate force (Figure 5).  They did not notice any other signs of instability but did note strong winds creating windslabs on east and northeast aspects.

Unstable conditions existed throughout the region. The KNF Avalanche Specialist was investigating three other human triggered incidents with no injuries from February 16 and 17 that failed on the same melt freeze crust/ facet layer.  The day before the accident, on February 21, the Bottom Line for the avalanche advisory read:

“The avalanche hazard in the West Cabinets, East Cabinets and Purcell Range is HIGH.  This means that very dangerous avalanche conditions exist on many terrain features, such as steep semi open slopes.  Natural avalanches are likely, and human triggered avalanches are very likely.  Backcountry travel in avalanche terrain is NOT recommended.

SPECIAL NOTE:  The Kootenai Region has received heavy storm loading since our last advisory (Tuesday 2-18-2014).   On Tuesday-Wednesday 2-18/19-2014, we experienced wind transport at all locations.”

At the time of the accident the skies were clear, winds calm and temperatures in the low 20’s F.

Figure 2: Snow Depth and Daily Snow at the Bear Mountain SNOTEL (5,400 ft.), West Cabinet Range, from January 21, 2014 to February 22, 2014. The accident occurred place on February 22, 2014.

Figure 2: Snow Depth and Daily Snow at the Bear Mountain SNOTEL (5,400 ft.), West Cabinet Range, from January 21, 2014 to February 22, 2014. The accident occurred place on February 22, 2014.

 

Figure 3: Air Temperature at the Bear Mountain SNOTEL (5,400 ft.), West Cabinet Range, from January 21 to February 22, 2014. The accident occurred on February 22, 2014. Note temperatures in Celsius.

Figure 3: Air Temperature at the Bear Mountain SNOTEL (5,400 ft.), West Cabinet Range, from January 21 to February 22, 2014. The accident occurred on February 22, 2014. Note temperatures in Celsius.

 

Figure 4: Photo of cornice development and wind loaded slope.

Figure 4: Photo of cornice development and wind loaded slope.

 

Figure 5: Pit profile from Moose Lake on February 20, 2014. 8 miles NW of the accident site. Courtesy of the Idaho Panhandle Avalanche Center

Figure 5: Pit profile from Moose Lake on February 20, 2014. 8 miles NW of the accident site. Courtesy of the Idaho Panhandle Avalanche Center

Avalanche: 

The Flathead Avalanche Center avalanche advisory for the Kootenai Region for February 21st read:  “The avalanche hazard in the West Cabinets, East Cabinets, and Purcell Range is HIGH.  This means that very dangerous avalanche conditions exist on many terrain features, such as steep semi open slopes.  Natural avalanches are likely, and human triggered avalanche are very likely.  Backcountry travel in avalanche terrain is NOT recommended.”

A member of the snowmobile party who was not buried provided valuable information regarding the accident site and all of the events of the day of the incident.  The snowmobiler is from the local area and visited the exact site two weeks earlier.  The events of 02/22/2014 started as two separate parties of two riders at the Spar Lake snowmobile trailhead (Figure 6).  At 0900, snowmobiler A and B arrived, unloaded and prepared for a trip to Whoopee Basin to play in the trees. 

Figure 6: Snowmobile route of travel

Figure 6: Snowmobile route of travel

At 0930, as they were departing the trailhead,   snowmobiler C and D arrived.  Up the trail, snowmobiler A forgot something at his truck and returned to the trailhead to get it.  At this time snowmobiler A, C, and D visited and decided to ride together for the day.  The now party of four traveled up the Spar Lake Road to the Spruce Lake junction, then to the Whoopee Basin Road (Figure 6).  At the end of Road 4623, they traveled cross country to the ridge west of Whoopee Basin.  Weather here was clear, cool (20°F), and calm.   At this point they played on a short open face known as the “vent area” that frames Whoopee Basin.  Not finding obvious signs of snowpack instability, they decide to proceed south and west along the ridge and drop into the head of East Fork Creek .  On this ridge, Rider A and Rider D made cell phone contact with their wives.  

Figure 7: View of the accident site looking roughly north. The Lunch Knoll was the location of Riders C and D when the avalanche occurred.

Figure 7: View of the accident site looking roughly north. The Lunch Knoll was the location of Riders C and D when the avalanche occurred.

At 1200 hours, the party played in the trees for approximately an hour before heading west to a “lunch knoll” (Figure 7) that provided a full view of “Fiberglass Hill”.  Rider B made a couple low loops on the open slope just above the trees.   At 1310, riders C and D are parked on the knoll, machines off, digging in their packs for lunch. Rider C has been sick all day and needed rest.  Rider A had become stuck 50 feet away after sinking a ski sideways against a tree.  This area is a swale terrain trap that fills to a depth of 15’-20’, nearly level with the lunch knoll to the south. 

Figure 8: Spar Peak Accident overview. Savage Mountain in the background 1.25 miles to the SW.

Figure 8: Spar Peak Accident overview. Savage Mountain in the background 1.25 miles to the SW.

 Rider B approached rider A and parked behind him facing uphill, engine off.  As rider B was unbuckling his helmet, he saw the avalanche approaching and yelled “avalanche, gotta go”.  Rider A yelled “run, run, run”.  Rider D (at the lunch knoll) successfully started his machine with one pull and departed a distance of 60 feet downslope.  Rider C pulled three times to try to start his machine, turned and ran 15 feet downslope.  Rider C described the avalanche noise as a tree top jet coming down on them.  The avalanche never reached rider C or D, or the lunch knoll.  In the deep snow, riders A and B did not get far before being overtaken by the avalanche.  Rider A stopped after running 30 yards to look back for Rider B and was swept face first into the edge of a 12” alpine fir’s six foot tree well.  He was completely buried except for his face.  He was on his stomach with his feet uphill and 3-4 feet below the surface. 

 Avalanche Specialists have classified the avalanche as being remotely triggered by the riders.  This determination was based on the location of the riders, the timing of the avalanche release in conjunction with the movement of the snowmobilers and the other incidents of remotely triggered avalanches recently in the area.  If the riders did remotely trigger the avalanche, it would take a couple of seconds or more for the failure to reach the ridge where the avalanche released.  It is likely that the riders remotely triggered the avalanche; however, there is a possibility that this avalanche was not triggered by the riders.

Figure 9: Overview of accident site.

Figure 9: Overview of accident site.

At approximately 1315, Riders C and D gathered their shovels and probe poles and started yelling for victims.  Rider C was 20 feet from Rider A when he heard him yell for help.  Rider C and D dug Rider A out in approximately 10 minutes (Figure 10). 

 Rider A was wearing a transceiver that they used to locate Rider B, who was completely buried.  Rider B was located approximately 25 feet northwest of a snowmobile ski tip that was protruding out of the avalanche debris.  In their digging efforts, Riders A, C and D realized that there was a tree buried in the snow between their initial hole and Rider B.  Rider D used the transceiver to search again and got a signal at 1.3 meters on the other side of the tree. They dug 10 minutes before they abandoned the initial hole (Figure 10).  At their new location, they reached Rider B in 5 – 7 minutes.  They encountered his right hand first at two feet deep.  Rider B’s face was uncovered at three feet, his helmet was gone.  His feet were angled down to a depth greater than six feet.  As soon as the face was uncovered Rider A gave several “rescue breaths” and initiated CPR as soon as the chest was exposed.  

Figure 10: View of the accident site looking roughly west.

Figure 10: View of the accident site looking roughly west.

By the time the victim was extracted from the burial site, over 30 minutes had elapsed.  Rider A and C continued CPR on the victim.  Rider D was sent two miles to make cell phone contact with 911. 

 At 1404, Rider D contacted Bonner County Sheriff’s Office.  He informed them of the avalanche incident, victim status, location and requested a helicopter.  BCSO responded that he is in “no man’s land” and they cannot respond, but will notify Lincoln County Sheriff’s Office.  The LCSO used cell phone coordinates to locate the incident and dispatched the ALERT Helicopter to the scene from Kalispell.  Approximately 45 minutes of CPR efforts continued until 1430 without response.  Rider D returned from the cell phone site at approximately 1500.  The party extracted Rider A’s 2013 SkiDoo 162, which started immediately with only the windshield was missing. 

 The ALERT Helicopter arrived from Kalispell but was unable to locate a safe landing spot near the incident.  The ALERT Helicopter was able to drop the party a hand held radio.

At approximately 1600, Flathead County Sheriff’s Office Air – 1 Helicopter with hoist capabilities arrived on scene.  A crew member and litter were lowered to the site for removal of the victim.  The ship circled the avalanche area while Riders A, C, D, and the helicopter crewmember prepped the body for transit and moved it to the lunch knoll.  The Air – 1 Helicopter returned and hoisted the litter into the ship, then returned to the helispot on the Mine road near the snowmobile trailhead. 

 The Air – 1 Helicopter returned to the scene to retrieve the helicopter crewmember, brought him back to the trailhead and then Nate Scofield, (LCSO Deputy) and Jon Jeresek (Kootenai National Forest Avalanche Specialist) boarded Air – 1 to examine and video the avalanche site.

 

During the flight, three snowmobilers on standby at the trailhead, with no affiliation to David Thompson Search and Rescue, self-dispatched themselves to the incident scene.  Riders A, C, and D left the site of the accident and met the three “resource riders” just west of the ridge dividing Whoopee Basin from the East Fork basin.  All six riders returned to the trailhead at approximately 1800.  Rider B’s 2008 Artic Cat M1000 remains at the scene buried at an unknown location.

 LCSO Deputy Nate Scofield interviewed each rider (A,C,D) individually in his patrol truck.  While at the trailhead, Kootenai National Forest Avalanche Specialist Jon Jeresek was able to visit informally with each of the survivors after their interview with Deputy Scofield.  

Figure 11: View of the accident site looking roughly northeast from the top of the ridge.

Figure 11: View of the accident site looking roughly northeast from the top of the ridge.

Search and Rescue:

David Thompson Search and Rescue was called out shortly after the 1404 call to 911.  Kootenai National Forest Avalanche Specialist Jon Jeresek was called at 1545 and asked to meet and advise DTSAR regarding a ground based rescue or recovery.  Jeresek is very familiar with the terrain accessing the incident site and advised against a ground based operation.  Four sections of avalanche terrain would need to be crossed twice to safely carry out such an operation.  It was agreed that the use of the Air – 1 Helicopter with hoist capabilities was the safest option to meet operational objectives. 

 

The snowmobile party’s efforts at self-rescue are described in the narrative above. 

-Rider A is an advanced rider with advanced first aid skills and intermediate avalanche skills.  He was wearing a transceiver that was Rider B’s only chance to be found.  His shovel was in his snowmobile which was buried.  We do not know if he carried a probe. 

-Rider B was an expert rider with intermediate avalanche skills.  He was wearing a transceiver which allowed him to be found.  We do not know if he carried a shovel/probe in a backpack or on his snowmobile. 

-Rider C is an advanced rider with advanced first aid skills and intermediate avalanche skills.  He had a shovel in a backpack, but no probe or transceiver. 

-Rider D is an advanced rider with advanced first aid skills and unknown avalanche skills.  He carried a shovel and a probe on him, but had no transceiver.  

     

COMMENTS

We wish to extend our condolences to the friends and family of the victim in this accident.  We would also like to thank the other members of the victim’s party for their willingness to share this important, detailed, and personal information. This information helps all of us learn in the context of a real situation, and helps promote sound backcountry decision making.  The Idaho Panhandle Avalanche Center and Flathead and Lincoln County Sherriff’s Offices should be thanked for their assistance as well as Two Bear Aviation for providing the video and photography.

REFERENCES

All formal notation and recording guidelines can be found in:
Greene, Ethan M., D. Atkins, K. Birkeland, K. Elder, C. Landry, B. Lazar, I. McCammon, M. Moore, D. Sharaf, C. Sterbenz, B. Tremper, and K. Williams, 2010. Snow, Weather, and Avalanches: Observational Guidelines for Avalanche Programs in the United States.  American Avalanche Association, Pagosa Springs, CO: Second Printing Fall 2010, 152 pp.

Figure 12: Topographic map of accident area

Figure 12: Topographic map of accident area

_________________________________________________________________________

 

The video below is a flyover investigation of the avalanche accident site. We thank Two Bear Aviation, Flathead County Sheriff, Lincoln County Sheriff, and the Kootenai National Forest for their efforts and providing us with video footage. We have edited down over 1 hour of video for preliminary information. More detailed weather, snowpack, and incident information will be provided in a full report by the Kootenai National Forest.

 

Updated information 2/23/2014-the Lincoln County Sheriff’s Department released additional details on the accident.

The following is a press release from the Lincoln County Sheriff’s Department with more information: 

On Saturday, February 22, 2014, at about 2:04 P.M., Lincoln County Sheriff’s Dispatch Center received a transferred 911 cell phone call from Bonner County Idaho.

The caller, Nathan Schwegel, of Libby, said that he was with a party of three other adult male snowmobilers about two miles north of Spar Peak. Spar Peak is about 17 miles southwest of Troy, Montana, in the West Cabinet Range near the Montana/Idaho border.

Schwegel said that two of the four snowmobilers in the party had been caught in a backcountry avalanche. One of the two avalanche victims was recovered ok. The other was recovered but was not breathing and the other two men were performing CPR.

Schwegel said that he had to ride his snowmobile about two miles from the avalanche site to obtain cell phone reception to make the call. The cell phone signal was used to assist with pinpointing the location of the incident.

David Thompson Search and Rescue was called out to respond. The ALERT helicopter out of Kalispell responded. The Air-One helicopter from Two Bear Air out of Kalispell also responded. Sheriff’s Office Detective Scofield responded along with Kootenai National Forest Avalanche Specialist Jon Jeresek of Libby, representing the Flathead Avalanche Center. USFS law enforcement officers also responded. All responders met at a staging and parking area well away from the remote avalanche site.

The ALERT helicopter arrived at the actual avalanche site first and reported that there was no location to land near the area. The Air-One rescue helicopter arrived next, at about 4:00 pm, and was able to conduct a vertical lift extraction of the victim.

The victim, Bryan William Harlow, age 49, of Libby, was pronounced dead and was flown to the staging area to be release to Coroner Steve Schnackenberg. The Air-One rescue helicopter then stayed on scene to assist the investigators. The three other avalanche victims then rode their machines out of the avalanche area to the staging area and did not need medical treatment.

Investigators learned that the snowmobilers had stopped in a low lying area within trees and were not moving at the time that the avalanche occurred. The men attempted to move clear of the avalanche, but two men were caught in the avalanche: Todd Byington, age 47 of Libby, and Bryan Harlow, age 49, of Libby. The other two men present were not caught by the avalanche: Nathan Schwegel, age 33, of Libby, and Jesse Mugford, age 27, of Libby. When the avalanche ceased, Schwegel and Mugford were able to hear Byington yelling, found him buried with only his face exposed, and dug him out. They all then used Byington’s avalanche beacon to locate Harlow’s avalanche beacon signal. They dug down and found Harlow buried under about four to six feet of compacted snow, but Harlow was not breathing. Byington and Mugford began CPR as Schwegel rode his snowmobile out of the area to find a cell phone signal. Byington and Mugford were not able to revive Harlow with CPR.

An on-site investigation will not be possible because of the high avalanche hazard in the area. Investigators conducted an aerial survey of the scene aboard the Air-One helicopter. Jeresek classified the avalanche as a D3 sized avalanche (SS-Amr-D3-R4-O) which means that it was a soft slab avalanche that was remotely snowmobile triggered; of a size that could destroy a car, damage a truck, destroy a wood frame house, or break a few trees; was large relative to the path; and was released within old snow.

The snowmobilers were aware of the current high avalanche danger and were taking precautions.

 

The Flathead Avalanche Center will assist avalanche specialists with the Kootenai National Forest as needed to develop an incident report. 

We have received preliminary information of an avalanche fatality in the West Cabinets this afternoon.

The fatality occurred at approximately 1:15 PM 2/22/2014 in the West Cabinet Range near Savage Mountain and the Idaho/Montana Border.  Approximately 15 miles SW of Troy.  The incident occurred within the Kootenai National Forest advisory area.

Out of a group of four snowmobilers, two were caught and buried by an avalanche.  One was buried with only his face exposed and was dug out with no injuries.  The other was fully buried and resulted in a fatality.  Preliminary reports classify the avalanche:  SS-AMr-D3-R4-O.  Soft Slab-Snowmobile triggered remotely-Could bury or destroy a car-large relative to the path-Released within old snow.

Additional information will be shared as it is available from the Kootenai National Forest. 

2/22/2014 Human Triggered Avalanches, Whitefish Range

Two human triggered avalanches reported today. These persistent slab avalanches likely failed on faceted weak snow above the late January crust. These deep avalanches are dangerous, destructive, often show no prior signs of instability, and are difficult to predict. Traveling in the backcountry these days requires very conservative decision making, cautious route-finding, avoiding steep slopes, and staying clear of runout zones of avalanche paths. 

2/22/2014
Two human triggered avalanches in Whitefish Range

1. McGinnis Creek drainage, located off of the North Fork Road north of Columbia Falls.
Six snowmobilers were traveling in the McGinnis Creek drainage on Saturday, February 22, 2014. One rider (Rider 1) had ascended the slope and was descending back down while two other riders (Rider 2 and 3) were off on the side of the slope when he triggered an avalanche. Rider 1 was knocked off of his machine, deployed his airbag (balloon), and was carried and estimated 150-200 yards downslope. He came to rest nearly fully buried in a reclining position with his airbag visible to his companions. He was able wiggle himself free and extricate himself. Rider 2 stayed on his machine on the outer edge of the avalanche, was carried downslope about 70 yards. His machine was partially buried and he was only buried a bit while sitting on his sled. Rider 3 was able to get away from his machine and stay out of the avalanche. His machine was fully buried near the toe of the debris. All were uninjured.
Preliminary information: The party involved estimates the avalanche to be about 200 yards wide with an approximate crown of 4 feet, and the debris traveled about 1000 vertical feet downslope. Flathead Avalanche Center staff are headed that way tomorrow (Sunday, 2/23) to investigate the avalanche.

Image of snowmobile path on slope below avalanche debris. McGinnis Creek, Whitefish Range. 2/22/2014.

Image of snowmobile path on slope below avalanche debris. McGinnis Creek, Whitefish Range. 2/22/2014.

 

Image of snowmobile path on slope below avalanche debris. McGinnis Creek, Whitefish Range. 2/22/2014.

Image of snowmobile path on slope below avalanche debris. McGinnis Creek, Whitefish Range. 2/22/2014.

 

 

 

 

 

 

 

 

 

 

 


2. China Basin, near Werner Peak, north of Whitefish

Seven snowmobilers/snowbikers were traveling in China Basin on Saturday, February 22, 2014. Two riders had already crossed the slope, two were in the middle of the slope near the avalanche crown, and three were in the back. A reporting member of the party believes one of the snowbikers up front triggered the slide. The avalanche knocked the last rider off of his machine and carried him down slope 30 to 40 feet. He ended up on top of the debris with no injuries. The location was reported as north of the china mans cabin on a leeward, east facing aspect The reporting member of the party involved estimates the crown was approximately 700+ feet wide, the debris was 4-5′ deep.

Debris and crown from snowmachine triggered avalanche in China Basin, Whitefish Range, 2/22/2014.

Debris and crown from snowmachine triggered avalanche in China Basin, Whitefish Range, 2/22/2014.

 

Crown from snowmachine triggered avalanche in China Basin, Whitefish Range, 2/22/2014.

Crown from snowmachine triggered avalanche in China Basin, Whitefish Range, 2/22/2014.

 

Google Earth image submitted by member of party involved. Yellow line designates crown, and red dot symbolizes location of individual knocked off machine by slide. China Basin, Whitefish Range, 2/22/2014.

Google Earth image submitted by member of party involved. Yellow line designates crown, and red dot symbolizes location of individual knocked off machine by slide. China Basin, Whitefish Range, 2/22/2014.

2/15/2014 – Avalanche Incident – Canyon Creek, Whitefish Range

Updated Information of Avalanche Incident in Canyon Creek – 2/15/2014

Also available as .pdf here.

Canyon Creek Avalanche Incident Report
Canyon Creek, Whitefish Range, MT
Date of Avalanche: 15 February 2014
Date of Investigation: 16 February 2014 

INCIDENT SYNOPSIS

On Saturday, February 15, 2014, a snowmobiler triggered an avalanche on a southeast facing (aspect 150 degrees) slope in the Canyon Creek drainage in the southern Whitefish Range. The slope the rider triggered the slide on is one of a series of southerly facing chutes known as the “Skook Chutes” or “Seven Sisters”. We investigated the avalanche on February 16, 2014. The avalanche failed on a layer of soft, faceted snow sitting on top of a hard, melt-freeze crust about 30 cm (13 in.) from the surface. It was approximately 275 m (900 feet) wide, ran 213 m vertical  (700 vertical feet) (from approximately 5930 feet to 5235 feet), and 387 m linear (1270 lineal feet). Avalanche debris reached and crossed the Canyon Creek Road (closed in winter and used as a groomed snowmobile trail), and was reported to be about 1.8 m (6 feet) deep on the road. We measured other debris piles not on the road at 2.5 – 4.5 feet deep. The debris reached the creek bottom below the road which is a terrain trap. The debris and bed surface were already covered by 5-20 cm (2-8 inches) of new snow overnight which made assessment slightly more difficult. 

The alpha angle (toe of debris to the crown of the avalanche) was 31.5 degrees. The average slope angle at the crown was 40 degrees. We received detailed information from an individual involved who was sitting on the Canyon Creek Road when the avalanche occurred. Four people were partially buried, and he was buried with only his right arm and head out of the debris.

The avalanche was classified: SS-AMu-D2-R4-I (This translates to a soft slab (SS) avalanche triggered unintentionally by a snowmobiler (AMu). The avalanche rates 2 out of 5 on the destructive scale (D2) which means it could bury, injure, or kill a person. It was large relative to the path (R4), and failed at the interface between the new and old snow (I).)

 

Following video courtesy of individual involved: 

 

 WEATHER AND SNOWPACK

Weather data are from the Whitefish Mountain Resort Ski Patrol Weather Log at the summit of Big Mountain in the southern Whitefish Range. These data are located about 2.8 km (1.7 miles) from the incident site. The closest SNOTEL site is Stahl Peak in the northern Whitefish Range about 60 km (37 miles) to the northwest. This site showed the average snow water equivalent to be 91% of median, and the precipitation to be 85% of average. The entire Flathead River Basin was 108% of median for snow water equivalent and 91% of average precipitation.

Beginning February 1, 2014, an arctic air mass parked itself over the region until around February 10, 2014. Prior to this a melt-freeze crust formed on sunny aspects throughout the advisory area. Small accumulations of snow occurred periodically and fell on this crust. During the cold air outbreak, the surface and near surface snow became weak and faceted causing weak layers to form on top of the melt freeze crust. The next notable precipitation commenced the afternoon of February 10, 2014 and snow accumulated incrementally through February 15, 2014 (date of incident) (Figure 1). During that arctic outbreak mountain temperatures reached below -20 °F (Figure 2). When the cold air mass exited the region, temperatures rose with new snowfall throughout the advisory area. This pattern created an upside down snowpack where heavier, dense snow fell on top of less dense, weaker snow. This new snow was accompanied by light to moderate winds according to Ski Patrol weather logs (Figure 3). On Wednesday and Thursday, February 12-13, 2014, an avalanche warning was issued for the entire advisory area with a hazard rating of HIGH.

 

20140215CanyonCreekWxSnow

Figure 1: Snow Depth and Daily Snow at Summit (6,817 ft.), Big Mountain, Whitefish Range, from February 8, 2014 to February 15, 2014. The event took place on February 15, 2014.

 

20140215CanyonCreekWxTemp

Figure 2: Air Temperature at Summit (6,817 ft.), Big Mountain, Whitefish Range, from February 8, 2014 to February 15, 2014. The event took place on February 15, 2014.

 

20140215CanyonCreekWxWind

Figure 3: Estimated Wind Speed and Direction at Summit (6,817 ft.), Big Mountain, Whitefish Range, from February 8, 2014 to February 15, 2014. The event took place on February 15, 2014.

 

Flathead Avalanche Center (FAC) staff were in nearby Kimmerly Basin and Skookoleel Creek as well as through Canyon Creek on Friday (2/14/2014) where they found unstable conditions on all aspects. They experienced collapsing, cracking, and unstable results in their Extended Column Tests (ECTs) in Kimmerly Basin. They found weak, faceted snow sitting on a crust in one of their snow pits on a southwest aspect. They observed no natural avalanches throughout the day. Temperatures steadily rose on the day of the avalanche and skies were clear and sunny until the late afternoon when clouds developed.

Unstable conditions existed throughout the region and the avalanche hazard was CONSIDERABLE in the Whitefish Range on the day of the incident. Other human triggered avalanches occurred on Saturday were reported that evening or Sunday. BNSF Avalanche Safety reported natural avalanche activity that occurred in the nearby Flathead and Lewis Ranges on Wednesday and Thursday prior to the date of this avalanche. No natural activity was reported or observed in the Whitefish Range in the days leading up to this incident. The bottom line in the avalanche advisory for that day read:
“Today, the avalanche hazard is CONSIDERABLE. This means that human triggered avalanches are likely and natural avalanches are possible. The snowpack is tender right now waiting for the right trigger. Dangerous avalanche conditions exist, and conservative decision making is essential. The advisory is a starting point, and the hazard could be higher or lower at any location which makes assessing each and every slope very important. The hazard could rise by the end of today as temperatures and snow levels rise later this afternoon. Pay attention to rapidly changing conditions.
Note: We are in a period of tricky and dangerous avalanche conditions. Very cautious backcountry travel is warranted. Since February 8, avalanches have killed six people and seriously injured three in the western United States in five separate incidents.”

 

AVALANCHE

FAC staff received a report of a snowmobile triggered avalanche on the evening of Saturday, February 15, 2014 in Canyon Creek in the Whitefish Range (Figure 4 and 5). Staff spoke with a local snowmobile rental company whose clients reported the avalanche to them. Initial reports were vague, but stated no one was seriously injured and everyone involved made it out without further incident. FAC staff visited the incident site on Sunday, February 16 (the day after the accident), and completed a fracture line profile on a southeast aspect (150 degrees) and found an approximately 30 cm (12 in.) slab sitting on a layer of faceted crystals over a 3 inch (8 cm) thick melt-freeze crust  (Figure 6 and 7). The bed surface of the avalanche was the melt-freeze crust at 30 cm (12 in.) below the surface. We were able to safely access the middle portion of the crown, but new snow and wind loading prevented a ground measurement of the width of the crown.

 

20140215CanyonCreekOveriewGE

Figure 4: Overview of avalanche site in Canyon Creek, Whitefish Range. The site is approximately 2.8 km (1.7 miles) from the summit of Whitefish Mountain Resort and designated as the white polygon.

 

 

20140215CanyonCreekSiteOverviewGE

Figure 5: Site overview of the avalanche in Canyon Creek, Whitefish Range. Skookoleel Peak (~6840 ft.) is the named peak on the background.

 

20140216CanyonCkProfile

Figure 6: Crown profile of the avalanche with failure layer denoted with red line.

 

 

 

20140215CanyonCkCrownProfileGeneralized

Figure 7: Generalized snow profile image at the crown of the avalanche.

 

 

Stability test results on the crown showed easy force to initiate a fracture which then propagated across the column (ECTP1 Q1). We moved about 2 m to the west and performed another ECT where the slab above the weak layer was a bit thicker (55 cm), and results, again, showed easy force to initiate fracture propagation (ECTP6 Q1).

The debris ran across the Canyon Creek Road (groomed snowmobile trail). Snowmobilers reported the debris on the road to be about 1.8 m (6 ft.). A groomer moved through the area later that afternoon/evening and groomed over the debris preventing measurement of the actual debris on the road. Off the road, though, we measured debris from 70-100 cm (28-51 in.) the next day. The total snow depth at the crown measured 127 – 155 cm (50-61 in.). This is a relatively shallow snowpack for the entire advisory area, but not uncommon on southerly facing slopes at this elevation. The avalanche ran approximately 700 vertical feet, 1270 linear feet, and was about 900 feet wide at the widest extent of the crown (Figure 8 – 10).

20140215CanyonCreekCloseupGE

Figure 8: Image of the avalanche extent (white polygon). The avalanche debris crossed the Canyon Creek Road which is a terrain trap.

 

20140215CanyonCkCrownOverviewAnnot

Figure 9: Looking up at the looker’s left portion of the avalanche crown from below Canyon Creek Road near the toe of the debris. Crown denoted by red line. The rest of the crown extends out of the image to the right.

 

 

20140215CanyonCkCrownCloseupAnnot

Figure 10: A closer view of the crown at the location we investigated it. Red arrows point to the crown. The rumpled snow at the bottom of the arrows is a glide crack covered in new snow.

 

 

A member of a party involved provided information to the Flathead Avalanche Center. We appreciate the willingness of the individual to share this information, and are glad everyone made it safely out of this situation (Figure 11 and 12). Rider 1 was in a group of 13 that started at the Canyon Creek Winter Trailhead along the North Fork Road (Highway 486), north of Columbia Falls, MT. They traveled using snowmobiles along the groomed snowmobile trail (Canyon Creek Road) to their intended destination – the summit of Big Mountain at Whitefish Mountain Resort. Seven members of the party traveled ahead and the remaining six stayed back to recreate on the slopes along the way to their destination. Rider 1 stated that they rode to a popular slope to recreate on. This slope is located approximately 0.7 km (0.4 miles) to the east of where the Canyon Creek Road splits to the main road and the “high” road. Rider 1 climbed the slope on his snowmobile himself and there were already many tracks on the slope. Rider 1 rode back to the road. Rider 1 was traveling with his two sons (Rider 2 and Rider 3). Rider 1, Rider 2, and Rider 3 were sitting on the Canyon Creek Road when they noticed the slope fracture. Given that the area is a terrain trap there was nowhere to safely ride out of the avalanche. The avalanche hit Rider 1 and he was knocked about 150 feet downslope of the road. He mentioned that he had time to think “Wow! I’m in an avalanche.” He began swimming as he was taught. When he came to rest his helmet was packed with snow and he immediately could not breathe. He discovered his right hand was free and was able to move snow away from his face. Rider 2 was located in a position where the debris moved around him, but his snowmobile stayed put on the road. Rider 3, who was also initially on the road was knocked off his snowmobile and carried downslope where he was able to self-extricate. Rider 4 & 5 were both stuck uplsope of the road when the avalanche occurred and were both carried downslope as well. Rider 4  had an inflatable backpack (airbag) which he deployed and stayed above the snow and debris. Rider 5 was partially buried as well, but was able to self-extricate. Rider 6 was further to the west on the road and was just missed by the debris. Rider 1 estimates there were six to seven other people in the area, but only the above four were partially buried. All those that were partially buried were able to either self-extricate or were dug out with assistance (Figure 11-13).

 

20140215CanyonCkCrownPartialBurial2

Figure 11: Location below road of Rider 1’s partial burial location. Rider 3 was buried to his waist next to the farthest tree to the right in image.

 

 

20140215CanyonCkCrownPartialBurial1

Figure 12: Location of partial burial above road.

 

Figure 13: Partially buried snowmobile on the Canyon Creek Road.

Figure 13: Rider 2’s partially buried snowmobile on the Canyon Creek Road.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Rider 1 provided detailed information regarding background information. This was Rider 1’s third time visiting this area. The last time he visited the area was around the New Year holiday this year. They did not read the avalanche advisory, but talked to some folks beforehand that mentioned the elevated avalanche hazard. They are aware of the avalanche advisory, but never check it. They normally carry avalanche safety equipment (beacon, shovel, probe), but left this gear in the trailer on this day. They were intending to “go for an easy ride” to the summit of Big Mountain. Rider 1 mentioned that he never gave a thought to an avalanche occurring on that slope.

Rider 1 has been snowmobiling for more than 40 years. His avalanche training consisted of avalanche awareness classes at a local snowmobile dealership in his hometown. He always felt he was a very cautious rider. He mentioned he noticed the avalanche area sign posted along the Canyon Creek Road on the way out, but not on the way to their intended destination.

 

COMMENTS

The staff at the Flathead Avalanche Center wish to extend our gratitude to Rider 1 for his willingness to share this important, detailed, and personal information. This information helps all of us learn in the context of a real situation, and helps promote sound backcountry decision making.

Canyon Creek is a very popular winter backcountry recreation area for both motorized and non-motorized users. Given the high use in this area it is important to recognize the potential for avalanches to impact multiple individuals who may or may not be in your party. This area is a classic terrain trap where there is nowhere to escape should an avalanche occur. Thus, it is important to remember for everyone to practice sound decision making and always carry avalanche rescue gear.

 

SEARCH AND RESCUE

No search and rescue operations were initiated as the individuals involved were able to extricate themselves.

Direct any questions regarding this report to fac.admin@flatheadavalanche.org or 406.261.9873.

Report prepared by Erich Peitzsch and Seth Carbonari of the Flathead Avalanche Center.

REFERENCES

All formal notation and recording guidelines can be found in:
Greene, Ethan M., D. Atkins, K. Birkeland, K. Elder, C. Landry, B. Lazar, I. McCammon, M. Moore, D. Sharaf, C. Sterbenz, B. Tremper, and K. Williams, 2010. Snow, Weather, and Avalanches: Observational Guidelines for Avalanche Programs in the United States.  American Avalanche Association, Pagosa Springs, CO: Second Printing Fall 2010, 152 pp.

 

 


 

From 2/16/2014: Preliminary Information of Avalanche Incident in Canyon Creek – 2/15/2014.

Yesterday, February 15, 2014, a snowmobiler triggered an avalanche on a southeast facing (aspect 150 degrees) slope in the Canyon Creek drainage in the southern Whitefish Range. The slope the rider triggered the slide on is one of a series of southerly facing chutes known as the “Skook Chutes” or “Seven Sisters”. We investigated the avalanche today (2/16/2014). The avalanche failed on a layer of soft, faceted snow sitting on top of a hard, melt-freeze crust about 12 inches (30 cm) from the surface. It was approximately 900 feet wide, ran 700 vertical feet (from approximately 5930 feet to 5235 feet), and 1270 lineal feet. Avalanche debris reached and crossed the Canyon Creek Road, and was reported to be about 6 feet deep on the road. We measured other debris piles not on the road at 2.5 – 4.5 feet deep. The debris reached the creek bottom which is a terrain trap. The debris and bed surface were already covered by 2-8 inches of new snow overnight which made assessment slightly more difficult. 

The alpha angle (toe of debris to the crown of the avalanche) was 31.5 degrees. The average slope angle at the crown was 40 degrees. We are awaiting a conversation with an individual involved, but it was reported that 4 individuals were partially buried, and everyone made it out. 

The avalanche was classified:
SS-AMu-D2-R4-I (This translates to a soft slab (SS) avalanche triggered unintentionally by a snowmobiler (AMu). The avalanche rates 2 out of 5 on the destructive scale (D2) which means it could bury, injure, or kill a person. It was large relative to the path (R4), and failed at the interface between the new and old snow (I).)

 

 

We will post a full report when we have more information. 

 

 

 

12/8/13 Avalanche Incident–Noisy Basin, Swan Range

Noisy Basin Avalanche Incident Report

Swan Range, MT

Date of Avalanche: 8 December 2013

Date of Investigation: 10 December 2013

 

 

INCIDENT SYNOPSIS

On Sunday, December 8, 2013, a party of two skiers was traveling in the Noisy Basin area near Camp Misery in the Swan Range, MT.  At approximately 1500, both skiers were descending a slope when they tritggered and avalanche that failed approximately 100 feet above them.  Skier #1 (a 36 year old male) was caught in the avalanche, carried downslope approximately 300 to 400 feet through some trees, lost one ski, and came to rest buried up to his neck in the snow.  He sustained a broken nose, lacerations to the face that required six stitches, multiple contusions and bruises, and a minor injury to his leg.  Skier #2 (a 35 to 40 year old male)was following a few turns behind Skier #1 and was also caught in the avalanche.  Skier #2 was carried downslope, sustained an injury to his knee when one of his skis was torn off, but was not buried.  Skier #2 was able to find Skier #1 downslope and dig him out.  They called a friend via a mobile phone to come help them with a snowmobile and slowly worked their way to the road to meet him. At this point they were able to depart for the trailhead.  An attempt at a site investigation occurred on Dec. 10 by Flathead Avalanche Center staff, but the site could not be located due to new snowfall and dangerous avalanche conditions. The information contained in this report became available on December 18. The avalanche occurred on a west facing aspect within a defined avalanche path.  The reported crown depth was approximately 8 to 10 inches, with a crown width of approximately 150 feet and ran approximately 500 vertical feet.  Approximate elevation of the crown was 6400 feet and the toe of the debris was 6200 feet (Figure 1).  The United States classification of the avalanche is SS-ASu-R4-D2-U (Greene e al. 2010).

 

 

noisy_12_8_13b 

Figure 1: Avalanche location in relation to Camp Misery and 12/14/13 avalanche

 

WEATHER AND SNOWPACK

December 8 was cold and clear in Noisy Basin with winds from the north/northwest at approximately 10 to 15 mph.  The week leading up to the incident was notably cold and dry with the presence of an arctic air mass, no new precipitation and temperatures averaging -15 to -25 degrees Fahrenheit.  The last significant snowfall was over a week previous to the incident (Figure 2).  The nearest remote weather station is Noisy Basin SNOTEL site, but this site lacks a wind sensor. However, based on other remote stations in the region and field observations, winds in the 48 hours prior to the incident were generally in the 15 to 20 mph range, gusting to 30 out of variable directions that included a substantial amount of time out of the north-northeast.  The skiers reported seeing wind slabs at Picnic Notch and also seeing a good deal of scour along the ridgeline to the south of Picnic Notch. 

 

 weather

Figure 2: Air temperature, snow water equivalent (inches) and snow depth (inches) from Noisy Basin SNOTEL site (elev. 6040 ft.) from December 1 to December 8, 2013. The incident took place on December 8, 2013.

 

 

AVALANCHE

The Flathead Avalanche Center Advisory for December 8 read:

“Overall, the avalanche hazard is MODERATE.  This means that human triggered avalanches are possible particularly on steep slopes with sensitive wind slabs and in isolated areas where buried surface hoar and crust layers are more reactive.”

 

The advisory listed WIND SLABS as an avalanche problem and identified possible atypical loading patterns due to north to northeast winds. No other avalanche activity was reported in the area during this time. One snowmobiler reported wind affected snow on convex rollovers near creek beds in the area.

 

Flathead Avalanche Center Staff received a very vague report of a skier triggered avalanche the evening of Sunday, December 8, 2013.  Staff spoke to the reporting party, who had no details on location or identity of those involved.  Flathead Avalanche Center staff members attempted to locate the avalanche site on December 10, but were unable because of new snowfall and dangerous avalanche conditions.  FAC staff continued to receive ambiguous reports on the incident until they obtained contact information and were able to contact the involved parties on December 18.  All information in this report is solely based on reports from the two parties involved. Flathead Avalanche Center staff last visited this area (Noisy Basin) on Friday, December 6.

 

From information received from the two skiers involved in the incident, the crown depth was approximately 8 to 10 inches (20-25 cm) deep and approximately 150 feet (45 m) wide and the slide ran approximately 500 feet (150 m) vertically.  Elevation of the crown was approximately 6400 feet (1950 m) and the toe of the debris approximately 6200 feet (1890 m).  The United States classification of the avalanche is SS-ASu-R4-D2-U (Greene e al. 2010). Because of the inability to conduct a crown profile, we can only speculate on the snowpack at the time of the incident using information from the skiers and other observations.  We speculate that the slope had some degree of wind loading from the previous days’ north and northeast winds and that the weak layer was an interface within that wind loaded portion of the snowpack. 

 

Skier #1 (36 year old male on telemark skis without straps) and Skier #2 (35 to 40 year old male on alpine skis) parked their vehicle at the Switchback Trail (#725) Trailhead around 1200 on Noisy Basin Road and skinned up the road from there.  They had planned on a quick tour, mostly for exercise and anticipated staying mostly within treed terrain.  Skier 2 checked the avalanche advisory in the morning and both were carrying a beacon, shovel and probe.  They consider themselves accomplished skiers with a good deal of experience in avalanche terrain, but have no formal avalanche education.  They ascended to Picnic Notch, noting some wind slabs in the notch, and continued south along the ridge to the slope they descended.  They descended through the trees to the opening where the avalanche occurred, catching it downslope of their intended location.  Skier #1 entered the opening (approximately 400 yards vertical by 100 yards wide) around mid-slope and found the snow “surprisingly good” his first couple of turns.  Skier #2 followed Skier#1 closely and made two turns before he realized the snow was moving.  Skier #1 made a few turns before everything started to move.  The slope had failed somewhere above him, approximately 100 feet.  Skier #1 was caught in the avalanche, carried downslope head first and struggled to swim. Skier #1 stated that after about 5 seconds, it “felt like someone hit me with a 2×6 across the face.” He was strained through some trees at the bottom and came to a stop after another 3 to 5 seconds.  Skier #1 came to rest in an upright position, buried up to his neck after being carried approximately 300 to 400 feet downslope.  He could breathe, but not move.  He had lost one ski, of which the binding had broken (Figure 3), and both poles, but one ski remained attached.  He received a broken nose, lacerations to the face which required 6 stitches, multiple bruises and contusions, and a minor leg injury.

Skier #2 provided this account:

 “My friend dropped in first and he made a turn in soft snow that looked great. I dropped in immediately after to make some 8s. I made two turns before I realized the snow was moving too. I stayed on top as I tried to head for the trees on my right as a possible safe zone when I realized I wasn’t getting there and it would take me more into the slide. I tried to go left and my ski got yanked off and my knee popped.  I tried to stay on top with my one remaining ski when I got tossed. The snow stopped and I wasn’t buried. I checked myself for injury and looked uphill to where I last saw my partner. I called out but didn’t hear a response. I scanned uphill for equipment a hand or anything when I heard him yell. I still thought he was above me when he yelled again and said “below you, hurry”. I scooted down on my one ski and grabbed his loose ski on my way to find him partially buried and pressed against a tree. He was bloody and moving slow. I dug out his legs and took off his one remaining ski. We called family and friends that headed up jewel basin road to get us at camp misery. My friend and I each hobbled down on one leg back to the road.”

 

Skier #2 lost one ski and a GOPRO camera.  His knee has some muscle damage that will keep him from skiing for approximately a month.

 

Ski Binding 2013 Avy 

Figure 3: Broken binding on Skier #1’s telemark ski

 

We appreciate both skiers speaking with us and sharing the details of the event so that they may be used to inform and educate others.  They also shared some of their lessons learned, in their own words below:

Lessons Learned (we have all heard before but reiterate):

-Commence descent of prone areas from the start zone as opposed to mid-slope to increase ability to keep the slide/slough debris downhill and find a safe exit.

-Descend one at a time and spaced apart.     

-Route Selection-It doesn’t take a lot of snow or a large exposed slope to result in a deadly slide.  Slide occurred on small exposed gash within generally treed/gladed area.  Trees/Anchors are a good thing unless you are being strained through them. 

-Familiarity-Both skiers can access this area from their living rooms.  It is easy to get complacent, especially with minimal early season snowpack and a generally unexposed route previously skied in all kinds of varying conditions and points during the year.”

 

 

SEARCH AND RESCUE

No search and rescue operations were initiated as the skiers were able to extricate themselves and return to their vehicles with some help from a friend with a snowmobile.

Direct any questions regarding this report to fac.admin@flatheadavalanche.org or 406.261.9873.

Report prepared by Seth Carbonari and Erich Peitzsch of the Flathead Avalanche Center.

REFERENCES
Greene, Ethan M., D. Atkins, K. Birkeland, K. Elder, C. Landry, B. Lazar, I. McCammon, M. Moore, D. Sharaf, C. Sterbenz, B. Tremper, and K. Williams, 2010. Snow, Weather, and Avalanches: Observational Guidelines for Avalanche Programs in the United States.  American Avalanche Association, Pagosa Springs, CO: Second Printing Fall 2010, 152 pp.

 

12/14/2013 Avalanche Incident – Picnic Notch, Noisy Basin, Swan Range

12/16/2013

Final report on Picnic Notch Avalanche Incident available
Click here for PDF

Picnic Notch Avalanche Incident Report
Noisy Basin, Swan Range, MT
Date of Avalanche: 14 December 2013
Date of Investigation: 15 December 2013

INCIDENT SYNOPSIS 
On Saturday, December 14, 2013, a party of two skiers was traveling in the Noisy Basin area near Camp Misery in the Swan Range, MT. Around noon, both skiers were ascending a slope they had previously descended. The skier in front (a 34 year old male) triggered an avalanche that released about 20 feet above him. He was caught in the avalanche and was carried to a tree where he came to rest fully buried except for one arm. He was able to extricate himself with this free arm and sustained no injuries. The avalanche occurred on a southwest facing slope that wraps around to more of a northwesterly aspect. A small sub-ridge bisects the slope causing cross loading of wind transported snow. The average slope angle of the starting zone was 39 degrees. The crown face depth averaged 12 inches with a maximum crown depth of 20 inches. The avalanche was approximately 250 feet wide and ran approximately 200 vertical feet. The crown was located at approximately 6700 feet in elevation and the toe of the debris was around 6620 feet. The caught skier was carried approximately 50 vertical feet. The United States classification of the avalanche is SS-ASu-R4-D2-I (Greene et al. , 2010).

WEATHER AND SNOWPACK
Weather data are from the Noisy Basin SNOTEL site (48.15˚N, 113.95˚W; 6040 ft.). Total Snow Water Equivalence (SWE) for this site was hovering around 140% of the 30-year median value. This station is located approximately 0.5 miles southwest of the incident site.

Beginning on Tuesday, December 10, 2013, an entrenched arctic air mass started moving east and a more westerly flow brought more seasonal temperatures (19-32 °F for Kalispell). During that arctic outbreak mountain temperatures reached below -20 °F. As the air mass moved east, a storm on December 9-10 deposited fairly low density (<10%) snow to the region. Snowfall amounts at Noisy Basin totaled about 16-20 inches (40-50 cm) with about 0.9 inches (22 mm) of snow water equivalent (SWE) (Figure 1). Since December 10, snowfall tapered and predominantly southwest winds increased on December 13 around the region. On December 14, a few inches accumulated throughout the day.

 

 20131214PicnicNotchTemp.jpg

20131214PicnicNotchSnow.jpg

Figure 1: Air temperature, snow water equivalent (inches) and snow depth (inches) from Noisy Basin SNOTEL site (elev. 6040 ft.) from December 9 to December 14, 2013. The event took place on December 14, 2013.

 

Avalanche activity (both natural and human triggered) was noted in the region from the onset of the storm on December 11 with a few reports until Thursday, December 12. Observations on the morning of December 14 by FAC staff in nearby Peters Ridge, Swan Range, noted no obvious signs of instability and no recent avalanche activity. The same was noted in the northern Flathead Range, but FAC staff observed substantial winds, wind loading, and “thick” wind slabs forming on leeward slopes. These slabs were not as “sensitive” in this location as expected.

 

FAC staff received a report of a skier triggered avalanche on the evening of Saturday, December 14, 2013. Staff spoke with the reporting party and received detailed information regarding the location and events. FAC staff visited the incident site on Sunday, December 15 (the day after the accident), and completed a fracture line profile on a southwest aspect and found a wind slab consisting of a variety of snow layers sitting on a layer of small faceted crystals over a 0.8 inch (2 cm) thick melt-freeze crust (from the warm, sunny period of late November) (Figure 2). 

 20131214_PicnicNotchAvalancheProfile

 Figure 2: Crown profile of the avalanche with failure layer denoted.

The bed surface of the avalanche was the melt-freeze crust at 12 inches (140 cm) below the surface. Above this crust was a cohesive wind slab ranging in depth from 12 inches (30 cm) to 20 inches (50 cm) across the crown. We were able to safely access the northern half of the crown, but a chute above the remainder of the crown that had not released posed a safety concern. FAC staff noted that the portion of the crown where the avalanche was triggered was much shallower and unsupportable. Ski penetration in this localized area was nearly to the ground.

 

Stability test results on the crown were mixed. The Extended Column Tests (ECTs) performed on the crown had no results (ECTX x2). Compression tests failed on the small facets with hard force (CTH 23, Q3). We noted cross loading from southwest winds while on site. The day of the investigation we did not see any new avalanche activity aside from the avalanche investigated nor did we experience cracking or collapsing of the snowpack along our ascent or descent. Other folks recreating in the area also mentioned that they had not seen any other avalanche activity that day.

 

We noticed that based on the reporting party’s description the avalanche was triggered from the skier’s right side (northern part) of the crown (Figure 3-5). The area where the avalanche was triggered was shallow relative to the rest of avalanche area. Thus, given this information it is probable that the skier initiated a fracture on a weak layer in this shallow area and the fracture propagated along a weak layer underneath a wind slab through the remainder of the slope. The debris ran through and over a small trap (small depression) at the bottom of the slope and continued a bit further downslope. The total snow depth at the crown was 78 inches (199 cm), and the measured debris was about 3 feet deep. The total snow depth in the deposition zone (debris plus existing snowpack was 116 inches (295cm). The avalanche ran approximately 200 vertical feet and about 400 linear feet.

20131214PicnicNotch1

Figure 3: Looking up at the crown of the avalanche. The skier triggered the slide on the left side of the image. The tracks were not evident both from substantial wind deposition overnight and the avalanche erased the tracks as well.

 20131214PicnicNotch2

Figure 4: Looking up at the crown of the avalanche. Substantial wind between the avalanche event and the site investigation transported snow and filled in some of the site, including the skier’s ascent and descent tracks. It was difficult to determine, but the tree in foreground of this image may be the tree that the skier was buried near. 

 20131214PicnicNotch3

Figure 5: Looking up the avalanche path with the crown visible. Note the rocky terrain above the crown as well as the small sub-ridge on the right side of the image. This small terrain feature (ridge) causes snow to be loaded and cross loaded onto this slope. The skier triggered the slide out of the image to the left.

AVALANCHE
The Flathead Avalanche Center avalanche advisory for December 14 read:

“The avalanche hazard is CONSIDERABLE on wind loaded slopes steeper than 30 degrees. The hazard is MODERATE on all other slopes. This means that human triggered avalanches are likely on steep slopes with sensitive wind slabs and possible on other slopes where facets and surface hoar still exist about 1-2 feet below the surface.

 The skier who triggered the avalanche provided valuable information regarding the accident site and all of the events of the day of the incident. Skier A (34 year old male) and Skier B (34 year old female) approached Noisy Basin along the Jewel Basin Rd. via snowmobile and parked at Camp Misery (Figure 6 and Figure 7). They checked the avalanche advisory before departing in the morning, and they each carried a beacon, shovel, and probe. They consider themselves expert skiers with about 14 years of backcountry skiing experience, and had taken “a couple” of Level 1 avalanche courses throughout the years.

20131214PicnicNotchGE_AreaOverview.jpg

Figure 6: Overview of avalanche site near Picnic Notch, Noisy Basin, Swan Range, MT.

20131214PicnicNotchGE_close

Figure 7: Close-up view avalanche site near Picnic Notch, Noisy Basin, Swan Range, MT.

During the morning, they headed toward Picnic Notch, ascended to the notch, and safely skied just skier’s left (south) of their uptrack. They then transitioned from downhill to uphill travel mode and began their second ascent toward Picnic Notch. They made progress up the slope via a series of switchbacks. Skier A then decided to go a bit further south to access an area with more potential vertical feet of skiing. This area is beneath a rocky section just south of Picnic Notch. As he continued upward in a southerly direction, he felt the snowpack consistency change and it “felt weird”. He then advised his partner to remain in her location. He took a few more strides and began to notice localized cracking of the snow. Just after this, he looked up to see the slope above him about 20 feet begin to avalanche. Still in uphill travel mode, his skis were not attached to his heels and his climbing risers on his bindings were still in an upright position. He immediately notified his partner that the slope was sliding and tried to put his climbing risers down to become more stable on his feet. He was instantly swept off his feet by the moving snow and transported down the slope in the debris. He made swimming motions and tried to spring out of the moving snow. He eventually hit a tree and remained in the “eddy” of the tree while debris moved around and over him. He became buried with only an arm sticking out of the snow. He mentioned that his mouth was full of snow at this time. He was able to brush the debris away using his arm and eventually free his head and airway. He was able to remove himself entirely from the debris. After assessing for injuries (of which there were none), he and his partner descended and debriefed the situation.

 Skier A mentioned a few points that are common in avalanche incidents and highlight the “human factor”.

  • He mentioned that on this day they did not dig a pit. He acknowledged that they typically dig snowpits in this area and in the past noticed the variability across the slope due to crossloading (i.e. shallow on one side and deep on the other).
  • He acknowledged that he and his partner on this day succumbed to the familiarity notion suggesting that the slope is safe after being safely descended nearby once earlier in the day. From many avalanche accidents, we know that it isn’t just the first person (or first time on the slope that day) that triggers the avalanche.
  • He also discussed that they had “let their guard down” after skiing the slope the first time, and they were headed back up for just one more run before departing.

We appreciate Skier A speaking with us and sharing the details of the event so that they may be used to inform and educate others.

SEARCH AND RESCUE
No search and rescue operations were initiated as the caught skier was able to extricate himself and was uninjured.

Direct any questions regarding this report to fac.admin@flatheadavalanche.org or 406.261.9873.

Report prepared by Erich Peitzsch and Seth Carbonari of the Flathead Avalanche Center.

 

REFERENCES
Greene, Ethan M., D. Atkins, K. Birkeland, K. Elder, C. Landry, B. Lazar, I. McCammon, M. Moore, D. Sharaf, C. Sterbenz, B. Tremper, and K. Williams, 2010. Snow, Weather, and Avalanches: Observational Guidelines for Avalanche Programs in the United States.  American Avalanche Association, Pagosa Springs, CO: Second Printing Fall 2010, 152 pp.


Previous post:
12/15/2013
Update to skier triggered avalanche in Swan Range on 12/14/2013.

A skier triggered avalanche was reported to the Flathead Avalanche Center (FAC) Saturday evening (12/14). FAC staff was able to speak with the skier who triggered the avalanche and was subsequently caught in the avalanche that evening.  The location was just skier’s left (south) of Picnic Notch and north of Crown Bowl in the Swan Range. The skier triggered the avalanche while ascending the slope after previously descending the slope. There were two members of the party and only one was caught.  The skier was caught and carried approximately 200 vertical feet downslope where he came to rest near a tree, fully buried with just one arm sticking out of the debris.  He was able to extricate himself using his free arm and was uninjured. 

FAC staff investigated the avalanche site today (12/15). The crown depth of the avalanche averaged approximately 12 inches and the maximum was 16-18 inches. The flanks were difficult to see due to overnight wind loading, but the width of the crown was estimated at approximately 200 feet. Debris ran approximately 500 vertical feet. It appears that the avalanche was triggered in a shallow part of the slope near rocks and propagated along a layer of small facets underneath a wind slab.

The avalanche was preliminarily classified as SS-AS-R4-D2-I. This was a soft slab avalanche unintentionally triggered by a skier. 

A full incident report will be published tomorrow (12/16/2013) on the FAC website.