21-22

Natural and skier triggered storm slabs

COOKE CITY
Cooke City
Code
SS-N-R3-D2-I
Elevation
9000
Aspect
SE
Latitude
45.02020
Longitude
-109.93800
Notes

Numerous 10-12" SS remote triggered avalanches on anything steep enough to slide where the new snow fell on solar crust. [Natural on] the cliffs on the north side of Companion Lake as you leave the lake heading for the wilderness boundary. Had not avalanched on the way out in the morning, noticed the avalanche on the way back this afternoon. Another avalanche skier triggered on intentional test slope with a solar tilt in the Alp Gulley."

Number of slides
2
Number caught
0
Number buried
0
Avalanche Type
Soft slab avalanche
Trigger
Natural trigger
R size
3
D size
2
Bed Surface
I - Interface between new and old snow
Problem Type
New Snow
Slab Thickness
12.0 inches
Vertical Fall
150ft
Slab Width
200.00ft
Slab Thickness units
inches
Single / Multiple / Red Flag
Multiple Avalanches
Advisory Year

GNFAC Avalanche Forecast for Tue Mar 15, 2022

Snowpack and Avalanche Discussion

<p>It is possible to trigger dangerous avalanches in the mountains around Cooke City after this weekend’s 13” of snow and associated wind (<a href="https://www.mtavalanche.com/weather/wx-avalanche-log"><strong>weather log</strong></a>). Slopes prone to wind loading or that have obvious drifts are the most likely to avalanche. Riding north of Cooke City yesterday, Alex saw natural and human-triggered avalanches mostly failing a foot deep, taking out the recent snow (<a href="https://www.mtavalanche.com/node/26193"><strong>photos and details</strong></a>, <a href="https://www.youtube.com/watch?v=5aiYFlLV05M&amp;list=PLXu5151nmAvT1nrM2…;). However, layers of weak snow buried around two feet deep make larger avalanches possible as Ian saw north of Scotch Bonnet last week (<a href="https://www.youtube.com/watch?v=BGiz4qC7pQg"><strong>video</strong></a&…;). A dozen observed avalanches since Saturday paint a clear picture about the possibility of triggering slides (<strong><a href="https://www.mtavalanche.com/avalanche-activity">avalanche activity</a></strong>). Avalanches becoming less likely as the snowpack adjusts, but patience or a thorough snowpack assessment is vital.</p>

<p>Look for signs of instability and test the upper few feet of the snowpack looking for information telling you to stay off steep slopes. Safe travel protocols provide a buffer if your assessment is wrong.</p>

<p>Today, the danger is MODERATE in the mountains around Cooke City. Snowfall this afternoon will increase the avalanche danger.</p>

<p>It is possible to trigger avalanches 6-18” deep on a melt-freeze crust or a layer of weak facets in the mountains around Bozeman, Big Sky and West Yellowstone. Strong winds will transport snow onto slopes where avalanches are most likely. Yesterday, skiers triggered multiple avalanches on the east face of Mount Blackmore, one from 50’ away (<a href="https://www.mtavalanche.com/node/26199"><strong>photos and details</strong></a>), and a group of snowmobilers sent in a photo of a slide on a wind-loaded slope below a cornice near Buck Ridge (<a href="https://www.mtavalanche.com/node/26195"><strong>photos and details</strong></a>). Two days ago, a skier took a nasty ride and sustained minor injuries in the backcountry outside of Big Sky Resort on a heavily wind-loaded slope when he triggered a 1000’ wide avalanche that carried him over rocks (<a href="https://www.mtavalanche.com/node/26184"><strong>photos and details</strong></a>). Sunday, in Beehive Basin, my partner and I found weak snow and bailed to a lower angle slope due to unstable test results at the top of a steep slope (<a href="https://www.youtube.com/watch?v=NTjHmlc7JHg"><strong>video</strong></a>…;

<p>Wet snow avalanches are possible, especially at lower elevations where temperatures will be warmer and precipitation may begin a rain.</p>

<p>Give yourself a chance to turn around by assessing the snowpack and looking for signs of instability before skiing or riding in avalanche terrain. The avalanche danger is MODERATE.</p>

<p>If you get out, please send us your observations no matter how brief. You can submit them via our website, email (mtavalanche@gmail.com), phone (406-587-6984), or Instagram (#gnfacobs).</p>

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Multiple Skier Triggered Avalanches on Mt. Blackmore

Mt Blackmore
Northern Gallatin
Code
SS-AS-R1-D1.5-O
Elevation
10000
Aspect
E
Latitude
45.44440
Longitude
-111.00400
Notes

Multiple avalanches were observed on the East face of Mt. Blackmore on 3/14/22. The avalanche depicted on looker's right was triggered by a ski cut 50' above the crown.  

Number caught
0
Number buried
0
Avalanche Type
Soft slab avalanche
Trigger
Skier
R size
1
D size
1.5
Bed Surface
O - Old snow
Vertical Fall
800ft
Slab Thickness units
centimeters
Single / Multiple / Red Flag
Multiple Avalanches
Advisory Year

From obs: "The slide was triggered Monday afternoon by us climbing up the slightly lower angle slope to the left.  It was an East facing slope at 9400’ above Muddy Creek drainage. We triggered lots of sluff slides in the new snow.  This small wind slab was the most significant action we got or saw all day, however, we mostly stayed well away from obviously loaded steep terrain."  

Northern Madison, 2022-03-14

Snowmobile triggered slide on Buck Ridge

Buck Ridge
Northern Madison
Code
R2-D1-O
Elevation
9400
Aspect
E
Latitude
45.21250
Longitude
-111.24800
Notes

This slide was triggered 3/14/22 by snowmobilers at Buck Ridge. The sslidewas triggered Monday afternoon by us climbing up the slightly lower angle slope to the left.  It was an East facing slope at 9400’ above Muddy Creek drainage. 

Number of slides
1
Number caught
0
Number buried
0
R size
2
D size
1
Bed Surface
O - Old snow
Slab Thickness
24.0 inches
Vertical Fall
100ft
Slab Width
50.00ft
Slab Thickness units
inches
Single / Multiple / Red Flag
Single Avalanche
Advisory Year

Natural avalanches in recent new snow Cooke City

COOKE CITY
Cooke City
Code
SS-N-R2-D2-I
Elevation
9500
Aspect Range
SW-NE
Latitude
45.02020
Longitude
-109.93800
Notes

We saw a few recent natural avalanches while riding north of Cooke City on 3/14/22. One on Crown Butte appeared to have run yesterday. A couple in the Rasta Chutes on Scotch Bonnet looked like they broke early this morning.

Number of slides
3
Number caught
0
Number buried
0
Avalanche Type
Soft slab avalanche
Trigger
Natural trigger
R size
2
D size
2
Bed Surface
I - Interface between new and old snow
Problem Type
New Snow
Slab Thickness units
centimeters
Single / Multiple / Red Flag
Multiple Avalanches
Advisory Year