23-24

Tiptoeing into Steeper Terrain

Date
Activity
Skiing

We went back to the Throne today and toured up to the ridge where 9 days ago Dave and I experienced a large collapse prompting us to decend our skin track. During our ascent, we had no signs of instability such as cracking or collapsing but were still cautious while walking through steep terrain. On the north side of the Throne, we found a shallow snowpack, 63 cm, and saw a stability score of ECTX. On the south side, we found a slightly deeper snowpack and again saw a score of ECTX in the snowpit

We felt good about going into this terrain for a couple of reasons. First, this area has had only a few reports of recent activity activity. Second, there was a clean runout below and the slope was barely over 30 degrees in steepness. All of this in addition to seeing no signs of instability and our stable test scores made us feel comfortable skiing from the top while taking a conservative approach and skiing one at a time. 

Region
Bridger Range
Location (from list)
The Throne
Observer Name
Zach Peterson

Bridger Peak and Argentina Bowl Photos

Date

These avalanche were noticed yesterday morning (2/20), possibly happened on 2/18-2/19.

Region
Bridger Range
Location (from list)
Bridger Peak
Observer Name
Alex Marienthal

Fresh slide over fresh ski tracks in Cooke

Date
Activity
Snowmobiling

Last Sunday we saw people touring up Scotch Bonnet and when we returned Monday we saw a large slide covering most of their tracks. 

Region
Cooke City
Location (from list)
Scotch Bonnet
Observer Name
NICHOLAS PINKHAM

GNFAC Avalanche Forecast for Wed Feb 21, 2024

Snowpack and Avalanche Discussion

<p>Stepping into backcountry avalanche terrain (slopes steeper than 30 degrees) anywhere in the advisory area is like stepping onto the casino floor with the odds stacked against you. You might win a hand or two, but you’ll likely lose in the long run. Persistent weak layers buried 2-4 feet deep under a slab of cohesive snow are failing and propagating widely. Yesterday, stronger winds drifting snow into thicker slabs on wind-loaded slopes, and 1-3” of new snow in the southern portions of the advisory area are a pair of aces in the dealer’s hand. Limited wet snow instability will increase as the day warms, especially in the Bridger Range.</p>

<p>Large avalanches and red flags indicating instability continue with alarming regularity. Yesterday, a group south of Cooke City triggered a collapse that rippled out over 100 feet (<a href="https://www.mtavalanche.com/node/30934"><strong><span>observation</span…;). Over the holiday weekend, groups reported natural avalanches on <a href="https://www.mtavalanche.com/node/30935"><strong><span>Bridger Peak</span></strong></a> and <a href="https://www.mtavalanche.com/node/30937"><strong><span>south of Saddle Peak</span></strong></a>. On Sunday, Doug and Alex triggered an avalanche from a long distance away near Buck Ridge while going to investigate a pair of large avalanches triggered on Saturday (<a href="https://www.mtavalanche.com/node/30869"><strong><span>video and observation</span></strong></a><strong>, </strong><a href="https://www.mtavalanche.com/node/30818"><strong><span>Saturday’s avalanches</span></strong></a>). In Cooke City, I watched shooting cracks race from our feet, propagating across an avalanche starting zone that was within a few degrees steepness of releasing and sliding (<a href="https://www.mtavalanche.com/node/30921"><strong><span>video and observation</span></strong></a>). Two large avalanches broke naturally in the Mount Bole basin in Hyalite Canyon (<a href="https://www.mtavalanche.com/node/30949"><strong><span>Photos and details</span></strong></a>). An avalanche failed and ran through thick trees in Tepee Basin (<a href="https://www.mtavalanche.com/node/30838"><strong><span>photo and details</span></strong></a>). A rider was partially buried in the Taylor Fork after getting caught, carried, and deploying an airbag (<a href="https://www.mtavalanche.com/node/30839"><strong><span>details</span></s…;). A number of snowmobilers triggered avalanches in Cooke City, including a large slide on the north side of Scotch Bonnet that broke 400 feet wide and up to 6 feet deep (<a href="https://www.mtavalanche.com/node/30780"><strong><span>photos, details, video</span></strong></a>). This is a small selection of the action detailed on our <a href="https://www.mtavalanche.com/weather/wx-avalanche-log"><strong><span>ava… and weather log</span></strong></a>.</p>

<p>Recreating in terrain less than 30 degrees steepness and minimizing your exposure to runout zones will keep you safe from avalanches (<a href="https://www.youtube.com/watch?v=_d5_vlY-bjg"><strong><span>use the 20-30 Rule</span></strong></a>). From the field, Ian and I recently advised against convincing yourself that conditions are safer based on limited signs of <em>stability</em> seen in snowpits or the absence of red flags (<a href="https://youtu.be/Tk29_PioWvQ"><strong><span>Cooke video</span></strong></a>, <a href="https://youtube.com/shorts/7ev8ez5wTvU"><strong><span>Bacon Rind video</span></strong></a>). Do not try to outsmart an unstable snowpack. The house will win sooner or later.</p>

<p><span>The danger is rated CONSIDERABLE. </span></p>

Upcoming Avalanche Education and Events

Our education calendar is full of awareness lectures and field courses. Check it out: Events and Education Calendar.

Every weekend in Cooke City: Friday at The Antlers at 7 p.m., Free Avalanche Awareness and Current Conditions talk, and Saturday from 10 a.m.-2 p.m. at Round Lake Warming Hut, Free Rescue Practice.

Natural Avalanches on Mt. Bole, Hyalite

Mt. Bole
Northern Gallatin
Code
N
Latitude
45.41560
Longitude
-110.99700
Notes

From obs: "From the approach trail to Mummy II we saw two large crowns on the ridge associated with Mt. Bole. Not sure when they happened, but they looked pretty big! Observed Monday morning, February 19"

Number of slides
2
Number caught
0
Number buried
0
Trigger
Natural trigger
Snow Observation Source
Slab Thickness units
centimeters
Single / Multiple / Red Flag
Multiple Avalanches
Advisory Year