22-23

Natural avalanche hit Daisy Pass road

Date
Activity
Snowmobiling

A snowmobiler saw this natural avalanche hit the Daisy Pass road within 10 minutes of riding by. He did a beacon search on the debris to confirm no one had been caught. It occurred about noon. This path is not very visible from the bottom and is not one that runs regularly. It killed a rider who was on the road in February 2012. The accident report has good photos of the path from afar.

Wind-loading in the start zone was the likely trigger since skiers and sledders do not access it.

From an email: "The crown was hard to see, but only looked a few feet deep where I could see it, but the debris pile was 10'+ on the road."

A big thanks to Dan Wykoff and Ben Zavora for providing the story and pictures.

Region
Cooke City
Location (from list)
Daisy Pass
Observer Name
Doug Chabot

GNFAC Avalanche Forecast for Sat Feb 25, 2023

Snowpack and Avalanche Discussion

<p><span><span><span><span><span><span>Strong winds continue to drift snow into thicker slabs that could avalanche naturally, or easily be triggered by a person. A few inches of new snow near Cooke City and West Yellowstone is being transported by strong southwest wind into fresh, unstable drifts. Earlier this week, the mountains received 2-4 feet of snow (1.5-4.5” of snow water equivalent) which was blown into drifts by wind from various directions, and a few large avalanches broke during the storm or immediately after (</span></span></span></span></span></span><a href="https://www.mtavalanche.com/weather/wx-avalanche-log"><span><span><span… and weather log</span></span></u></span></strong></span></span></span></a><span><span><span><span><span><span>). These large drifts remain possible to trigger, and could avalanche naturally with additional weight from wind-drifted snow.&nbsp;</span></span></span></span></span></span></p>

<p><span><span><span><span><span><span>Doug was in Cooke City yesterday and had a drift collapse and “whumph” as he stepped on it (</span></span></span></span></span></span><a href="https://www.youtube.com/watch?v=F8XdEKnZqVM&amp;list=PLXu5151nmAvTi1DBS…;). Yesterday near Buck Ridge a rider triggered a 2 foot thick avalanche of last week’s wind-drifted snow (</span></span></span></span></span></span><a href="https://www.mtavalanche.com/node/28293"><span><span><span><strong><span… and details</span></span></u></span></strong></span></span></span></a><span><span><span><span><span><span>). Skiers on Mt. Blackmore saw a 2 foot deep large natural avalanche (</span></span></span></span></span></span><a href="https://www.mtavalanche.com/images/23/large-natural-wind-slab-mt-blackm…;), and skiers in Beehive saw a very large cornice collapse (</span></span></span></span></span></span><a href="https://www.mtavalanche.com/images/23/natural-cornice-collapse-beehive"…;). Both appeared to have happened within the previous day.</span></span></span></span></span></span></p>

<p><span><span><span><span><span><span>Today, wind-loaded slopes are dangerous, and cautious route finding and conservative decision making are essential. Carefully assess the snowpack for signs of recently formed drifts. Drifts often appear as round or smooth pillows and form below cornices and convex rolls and on the opposite side of scoured ridgelines. Seek out slopes that do not have recent drifts or slopes that are less than 30 degrees steep. Today the avalanche danger is CONSIDERABLE on wind-loaded slopes and MODERATE on all 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>

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Large natural wind slab avalanche Mt. Blackmore

Mt Blackmore
Northern Gallatin
Code
HS-N-R2-D2-I
Elevation
9500
Aspect
E
Latitude
45.44440
Longitude
-111.00400
Notes

From IG: Skiers near Mt. Blackmore on 2/24 saw a large avalanche on the east side of Mt. Blackmore that appeared to have happened in the last 24 hours.

Number of slides
1
Number caught
0
Number buried
0
Avalanche Type
Hard slab avalanche
Trigger
Natural trigger
R size
2
D size
2
Bed Surface
I - Interface between new and old snow
Problem Type
Wind-Drifted Snow
Slab Thickness
24.0 inches
Vertical Fall
700ft
Slab Width
100.00ft
Slab Thickness units
inches
Single / Multiple / Red Flag
Single Avalanche
Advisory Year

Natural avalanche on Emigrant Peak

Emigrant Peak
Out of Advisory Area
Code
N-R3-D2
Elevation
9000
Aspect
E
Latitude
45.26300
Longitude
-110.70700
Notes

From IG message 2/24/23: HS-N-R2.5-D2-O. In emigrant gulch on an east aspect around 9k feet. Seemed to have stepped down on to a PWL, however it’s pretty tough to tell.

 

 

Number of slides
1
Number caught
0
Number buried
0
Trigger
Natural trigger
R size
3
D size
2
Problem Type
Wind-Drifted Snow
Slab Thickness
18.0 inches
Vertical Fall
800ft
Slab Width
200.00ft
Snow Observation Source
Slab Thickness units
inches
Single / Multiple / Red Flag
Single Avalanche
Advisory Year

From IG message 2/24/23: "HS-N-R2.5-D2-O. In emigrant gulch on an east aspect around 9k feet. Seemed to have stepped down on to a PWL, however it’s pretty tough to tell." Photo: O. Desroches

 

 

Out of Advisory Area, 2023-02-25

Natural Cornice Collapse in Beehive

Beehive Basin
Northern Madison
Code
C-N-R3-D2
Elevation
9300
Aspect
E
Latitude
45.32990
Longitude
-111.38200
Notes

Came across this very large cornice that appeared to have broken naturally sometime in the past 24 hours. Saw a few others that had broken recently throughout our tour, but none as large as this.

Number of slides
1
Number caught
0
Number buried
0
Avalanche Type
Cornice fall
Trigger
Natural trigger
R size
3
D size
2
Problem Type
Cornice Fall
Slab Thickness units
centimeters
Single / Multiple / Red Flag
Single Avalanche
Advisory Year

From email 2/24/23: "Came across this very large cornice that appeared to have broken naturally sometime in the past 24 hours. Saw a few others that had broken recently throughout our tour, but none as large as this." E. Heiman

Northern Madison, 2023-02-25

Rider triggered wind slab Buck Ridge

Buck Ridge
Northern Madison
Code
SS-AM-R3-D1.5-I
Elevation
9500
Aspect
NE
Latitude
45.17190
Longitude
-111.38000
Notes

Triggered a small 2’ deep wind slab in new snow this afternoon.  NNE aspect 9,500’, approximately 38° slope.  Riding was excellent on all high North facing slopes and this was the only sign of instability we saw all day.  Wind was howling on the way out, lots of snow coming out of the trees and transporting at ridge tops.

Number of slides
1
Number caught
0
Number buried
0
Avalanche Type
Soft slab avalanche
Trigger
Snowmobile
R size
3
D size
1.5
Bed Surface
I - Interface between new and old snow
Problem Type
Wind-Drifted Snow
Slab Thickness
24.0 inches
Vertical Fall
75ft
Slab Width
50.00ft
Snow Observation Source
Slab Thickness units
inches
Single / Multiple / Red Flag
Single Avalanche
Advisory Year