21-22

GNFAC Avalanche Forecast for Tue Mar 22, 2022

Snowpack and Avalanche Discussion

<p>It is possible to trigger an avalanche on steep slopes across the advisory area today. This weekend 2-10” of snow fell favoring the mountains around Bozeman and Big Sky. Slopes with recent drifts of wind-loaded snow are the most likely place to trigger an avalanche. These could break 1-2’ deep and 100’+ across. While the northern portions of the advisory area got the most snow this weekend, the story is fundamentally the same in the southern ranges.</p>

<p>Yesterday, skiers triggered avalanches both north and south of the Bridger Bowl Ski Area boundaries and were thankfully able to ride out of the slides (<a href="https://www.mtavalanche.com/node/26289"><strong>Saddle Peak photo and details</strong></a>, <a href="https://www.mtavalanche.com/node/26293"><strong>north of boundary details</strong></a>). And, a sledder rode away after triggering an avalanche on Cedar Mountain (<a href="https://www.mtavalanche.com/node/26295"><strong>photo and details</strong></a>). Sunday night, many new snow avalanches ran in the Divide Peak Cirque in Hyalite Canyon (<a href="https://www.mtavalanche.com/node/26290"><strong>details</strong></a&gt;) and a large avalanche broke under cliffs on a wind-loaded slope on Cedar Mountain (<a href="https://www.mtavalanche.com/node/26292"><strong>photo and details</strong></a>). On Saturday, Ian and Alex saw two avalanches triggered by cornice fall in the Lionhead area (<a href="https://www.youtube.com/watch?v=xc770oqXMsE&amp;list=PLXu5151nmAvT1nrM2…;, <a href="https://www.mtavalanche.com/node/26265"><strong>photos and details</strong></a>) and skiers in the Republic Creek drainage near Cooke City saw a similar slide (<a href="https://www.mtavalanche.com/node/26275"><strong>photo and details</strong></a>). Touring in the Bridger Range on Sunday, Doug warned us in his <a href="https://www.youtube.com/watch?v=6UH-zaFfU3c"><strong>video</strong></a&…; that in higher elevations where the winds are blowing, he expected to see more avalanches.</p>

<p>Temperatures will warm above freezing under clearing skies today. This afternoon, unconsolidated snow in the upper snowpack on south-facing slopes and at lower elevations will get wet, lose strength and become more likely to avalanche. Shift to slopes where the snow surface is cooler and consider the terrain you will need to return through on your way home.</p>

<p>A weak layer of facets is buried 1-3’ deep on many slopes that could allow slides to initiate more deeply and propagate across wider areas. These avalanches are less likely but more dangerous. Skiers in Bear Basin this weekend heard a loud “whumph” when they collapsed these weak layers (<a href="https://www.mtavalanche.com/node/26274"><strong>details</strong></a&gt;). I investigated a skier-triggered avalanche that broke 18” deep and 500’ wide in Wyoming Bowl on weak faceted snow a week ago (<a href="https://www.mtavalanche.com/node/26184"><strong>video and details</strong></a>).</p>

<p>Today, evaluate the snowpack and terrain carefully. Be skeptical of stability in recently wind-loaded terrain and on steep south-facing slopes prone to warming in the afternoon. The 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>

Snomobile Triggered Avalanche on Cedar Mountain

Cedar Mtn.
Northern Madison
Code
SS-AM-R1-D1-I
Latitude
45.22680
Longitude
-111.51200
Number of slides
1
Number caught
0
Number buried
0
Avalanche Type
Soft slab avalanche
Trigger
Snowmobile
R size
1
D size
1
Bed Surface
I - Interface between new and old snow
Slab Thickness
12.0 inches
Slab Thickness units
inches
Single / Multiple / Red Flag
Single Avalanche
Advisory Year

Skier Triggered Avalanche North of Bridger Bowl

Bridger Bowl
Bridger Range
Code
SS-AS-O
Latitude
45.81560
Longitude
-110.92300
Notes

BBSP reported a skier-triggered avalanche north of the ski area boundary. Minimal information. No one was caught that we know of. 

Number of slides
1
Number caught
0
Number buried
0
Avalanche Type
Soft slab avalanche
Trigger
Skier
Bed Surface
O - Old snow
Slab Thickness units
centimeters
Single / Multiple / Red Flag
Single Avalanche
Advisory Year

Natural Avalanche Cedar Mountain

Cedar Mtn.
Northern Madison
Code
N-R2-D2
Elevation
9900
Aspect
NE
Latitude
45.22680
Longitude
-111.51200
Notes

Patrollers at the Yellowstone Club spotted a natural avalanche on a steep, wind-loaded slope that failed on March 20th. 

Number of slides
1
Number caught
0
Number buried
0
Trigger
Natural trigger
R size
2
D size
2
Problem Type
Wind-Drifted Snow
Vertical Fall
400ft
Slab Width
150.00ft
Slab Thickness units
centimeters
Single / Multiple / Red Flag
Single Avalanche
Advisory Year