22-23

Large Skier Triggered Avalanche NE Face Hyalite Pk

Date
Activity
Skiing

(NE, HS, ASu, D3, R4)

We toured into Hyalite with the intention of skiing the North East Face of Hyalite Peak. Our primary concern was wind loading on leeward slopes. Before starting the day 6" of snow was reported in the Northern Gallatin range however we only found up to three inches of new snow. Approaching the saddle we found soft snow (2-3") on a pencil-hard crust. Once reaching the summit we descended carefully onto the NE face observing a shooting crack on a pocketed soft wind-slab after performing a ski cut. Noting this we descended further staying on the ridgeline. We then found a similar snowpack to the saddle with no cracking after a few more ski cuts and decided to ski one at a time down the duration of the face. Skier 1 skied a few turns down the face when a loud wumph was heard and the whole face started sliding. Skier 1 was caught, carried, and partially buried at the tail of the slide path. Skier 2 observed skier 1 and skied down to them after the avalanche stopped. Skier 1 was then fully dug out and both skiers left the avalanche path unharmed. The slide was thought to be (D3,R4) breaking all the way to the ground and spanning at least 500' wide. 

Region
Northern Gallatin
Location (from list)
Hyalite Peak

Avalanches between Mammoth to Tower

Date

During wolf watching this morning we noticed large areas of avalanching snow between Mammoth-Balacktail-Tower. Break face 2-3 feet. Slope was only 20%. We were very surprised to see this terrain producing avalanches. 

Observer Name
Steve Braun

GNFAC Avalanche Forecast for Sat Mar 4, 2023

Snowpack and Avalanche Discussion

<p><span><span><span><span><span><span>Dangerous avalanche conditions exist near Cooke City. Human-triggered avalanches are likely which could break 3-6 feet deep. On Thursday near Daisy Pass, skiers triggered a large avalanche that buried their snowmobile parked on the groomed trail below and barely missed a group of riders that had just passed by (</span></span></span></span></span></span><a href="https://www.mtavalanche.com/node/28413"><span><span><span><strong><span… and details</span></span></u></span></strong></span></span></span></a><span><span><span><span><span><span>). Yesterday a snowmobiler triggered a thick slab of wind-drifted snow on a small slope (</span></span></span></span></span></span><a href="https://www.mtavalanche.com/images/23/snowmobile-triggered-slide-near-c…;). Over the last two weeks, this area received snow every day except one, and moderate to strong winds drifted snow into thick, heavy slabs. There have been many large natural avalanches, the most recent on Tuesday (</span></span></span></span></span></span><a href="https://www.mtavalanche.com/images/23/very-large-avalanche-henderson-cr…;, </span></span></strong></span></span></span><a href="https://www.mtavalanche.com/images/23/natural-avalanche-miller-ridge"><…;), and three human-triggered avalanches last weekend resulted in partial burials and luckily nothing worse (</span></span></span></span></span></span><a href="https://www.mtavalanche.com/node/28338"><span><span><span><strong><span… Hill</span></span></u></span></strong></span></span></span></a><span><span><span><span><span><span>, </span></span></span></span></span></span><a href="https://www.mtavalanche.com/node/28322"><span><span><span><strong><span… Lake</span></span></u></span></strong></span></span></span></a><span><span><span><span><span><span>, </span></span></span></span></span></span><a href="https://www.mtavalanche.com/node/28331"><span><span><span><strong><span…. Abundance</span></span></u></span></strong></span></span></span></a><span><span><span><span><span><span>). There are various buried weak layers, and recent avalanche activity is enough evidence to show the snowpack has been pushed to its breaking point. Today, cautious route finding and conservative decision making are essential. Avoid riding on slopes steeper than 30 degrees, especially if they are wind-loaded, and be extra cautious crossing below steep slopes. Avalanche danger is CONSIDERABLE.</span></span></span></span></span></span></p>

<p><span><span><span><span><span><span>From Big Sky to West Yellowstone there are buried weak layers that make it possible for a person to trigger a large avalanche. Yesterday on Buck Ridge, riders triggered an avalanche a few feet deep that looks like it broke on an older buried weak layer (</span></span></span></span></span></span><a href="https://www.mtavalanche.com/images/23/snowmobiler-triggered-slide-buck-…;). Earlier in the week, a snowmobiler triggered a similar sized slide in Cabin Creek (</span></span></span></span></span></span><a href="https://www.mtavalanche.com/images/23/sled-triggered-avalanche-cabin-cr…;), and a natural avalanche in Taylor Fork broke on a layer of surface hoar (</span></span></span></span></span></span><a href="https://youtu.be/K9abJNvfWOs"><span><span><span><strong><span><u><span>…;, </span></span></span></span></span></span><a href="https://www.mtavalanche.com/images/23/natural-avalanche-sage-basin-3"><…;). Before riding steep slopes, carefully assess for wind-loading and buried weak layers. If you suspect either, find lower angle terrain. Today, avalanches are possible to trigger and avalanche danger is MODERATE.</span></span></span></span></span></span></p>

<p><span><span><span><span><span><span>In the Bridger Range and Hyalite up to a foot of snow fell over the last week. This snow was drifted into thicker slabs that can be triggered by a person. Doug was in Hyalite on Thursday and found recent drifts to be bonding well (</span></span></span></span></span></span><a href="https://www.youtube.com/watch?v=oFmfbuKkv5c&amp;list=PLXu5151nmAvTi1DBS…;), but fresh drifts have formed and a few old drifts may remain unstable. Before riding or crossing steep slopes, carefully assess the stability of wind-drifted snow. Watch for cracking across the snow surface as a sign unstable drifts exist, and dig down a couple feet to test stability of older wind slabs. On non-wind loaded slopes avalanches are unlikely. We have not seen slides break on widespread buried weak layers in these mountains over the last couple weeks, but it is still worth digging to check stability before committing to steep slopes. Today the avalanche danger is MODERATE on wind-loaded slopes and LOW on other slopes.</span></span></span></span></span></span></p>

<p><span><span><span><span><span><span>Please share avalanche, snowpack or weather observations via our</span></span></span></span></span></span><a href="https://www.mtavalanche.com/node/add/snow_obs"><span><span><span><span>…; </span></span></span></span></span></span><span><span><span><strong><span><u><span><span>website</span></span></u></span></strong></span></span></span></a><span><span><span><span><span><span>, email (</span></span></span></span></span></span><span><span><span><strong><span><span>mtavalanche@gmail.com</span></span></strong></span></span></span><span><span><span><span><span><span>), phone (406-587-6984), or Instagram (#gnfacobs).</span></span></span></span></span></span></p>

<p><span><span><span><span><span><span>Dangerous avalanche conditions exist in Island Park. Over the last couple weeks, this area received feet of heavy snow which drifted into thick slabs, and more snow is expected today and tomorrow (</span></span></span></span></span></span><a href="https://www.mtavalanche.com/node/28422"><span><span><span><strong><span… observation</span></span></u></span></strong></span></span></span></a><span><span><span><span><span><span>). This steady, continuous addition of weight has pushed the snowpack to its breaking point. Large avalanches are likely to be triggered and could break naturally. Avoid riding on slopes steeper than 30 degrees, especially if they are wind-loaded, and be extra cautious crossing below steep slopes.</span></span></span></span></span></span></p>

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Natural avalanches north of Miller

Date

from text 3/3/23: "[talked to some skiers in the coffee shop] saw multiple natural avalanches yesterday [3/2] on the north side of Miller in Abundance...."

Region
Cooke City
Location (from list)
Miller Mtn.
Observer Name
Zach Peterson

Snowmobiler triggered slide Buck Ridge

Buck Ridge
Northern Madison
Code
HS-AM-R3-D2-O
Elevation
9200
Aspect
E
Latitude
45.17660
Longitude
-111.37100
Notes

From FB mesage: "Buck ridge. East facing slope. Beaver creek area. Sled triggered. No burials."

Number of slides
1
Number caught
0
Number buried
0
Avalanche Type
Hard slab avalanche
Trigger
Snowmobile
R size
3
D size
2
Bed Surface
O - Old snow
Problem Type
Persistent Weak Layer
Slab Thickness
36.0 inches
Vertical Fall
75ft
Slab Width
100.00ft
Snow Observation Source
Slab Thickness units
inches
Single / Multiple / Red Flag
Single Avalanche
Advisory Year

Snowmobile triggered off HWY 212

COOKE CITY
Cooke City
Code
HS-AM-R3-D1
Elevation
8000
Aspect
SE
Latitude
45.02020
Longitude
-109.93800
Notes

Here is a picture of an avalanche that occurred between Daisy and lulu road just off HWY 212 today. SE facing slope that was snowmobile triggered

Number of slides
1
Number caught
0
Number buried
0
Avalanche Type
Hard slab avalanche
Trigger
Snowmobile
R size
3
D size
1
Problem Type
Wind-Drifted Snow
Slab Thickness
30.0 inches
Vertical Fall
75ft
Slab Width
40.00ft
Snow Observation Source
Slab Thickness units
inches
Single / Multiple / Red Flag
Single Avalanche
Advisory Year

Snowmobiler triggered slide Buck Ridge

Date
Activity
Snowmobiling

From FB mesage: "Buck ridge. East facing slope. Beaver creek area. Sled triggered. No burials."

Region
Northern Madison
Location (from list)
Buck Ridge

Another Cooke City avalanche

Date

Here is a picture of an avalanche that occurred between Daisy and lulu road just off HWY 212 today. SE facing slope that was snowmobile triggered

Region
Cooke City
Location (from list)
COOKE CITY
Observer Name
Ben Zavora