18-19

Days of heavy snow and strong winds created unstable conditions in the mountains near Big Sky. This massive natural avalanche was observed on Wilson Peak north of Big Sky Ski Resort. As snow and wind subside, conditions will gradually become more stable. Photo: C. Babineau-Z

Northern Madison, 2019-03-01

Avalanche Fatality, Truman Gulch

On February 26, 2019 a 36 year old male skier (Skier 1) was caught and killed in an avalanche on the west side of the Bridger Range near Bridger Bowl Ski Area. He accessed backcountry terrain by riding the Schlasman’s Chairlift at Bridger Bowl before leaving the ski area boundary to the west. At approximately 1400 hours he dropped into a northwest facing slope at the top of the St. Lawrence

GNFAC Avalanche Forecast for Fri Mar 1, 2019

Snowpack and Avalanche Discussion

<p>The snowpack in these areas is heavily loaded and remains under a significant amount of stress. Over the past week, the mountains near Cooke City, West Yellowstone, including the Sothern Madison and Gallatin Ranges - have received 4-6’ of snow totaling 4-7” of SWE. This is an insane amount of snow and water weight!</p>

<p>Every structure has a breaking point and the snowpack is no different (<a href="https://www.youtube.com/watch?v=vXUCG2z6fYI&amp;list=PLXu5151nmAvRNl9ku…;). Today, natural and human triggered avalanches are likely on all steep slopes. A large natural avalanche that crossed Hwy 287 near Quake Lake yesterday is a perfect example of what’s possible today (<strong><a href="https://www.mtavalanche.com/images/19/avalanche-across-road-quake-lake-…;). Slides will break deeper and run farther than expected. Under these conditions it’s very easy to get surprised.</p>

<p>Traveling in the backcountry today requires expert terrain management. It’s imperative that all backcountry travelers stay off and out from underneath all steep slopes (<strong><a href="https://www.mtavalanche.com/images/19/natural-avalanche-cooke-city-0">p…;). This includes small terrain features such as road cuts, roll overs and creek bottoms.</p>

<p>Today, very dangerous avalanche conditions exist and the avalanche danger is rated <strong>HIGH</strong>.</p>

<p>The mountains near Bozeman and Big Sky have picked up 2-3’ of snow totaling 2-3” of SWE over the past week. This hasn’t been quite enough load to create a widespread avalanche cycle, but is has pushed the snowpack near it’s breaking point.</p>

<p>Wind loaded slopes will be the most unstable and could fail naturally today (<strong><a href="https://www.youtube.com/watch?v=w1PHAN4n83A">video</a></strong&gt;). The avalanche fatality two days ago in the Bridger Range is a sad reminder of how unstable wind loaded slopes can be (<strong><a href="https://www.mtavalanche.com/avalanche-incidents">details, photos</a></strong>). A skier triggered slide two days ago on a wind loaded slope near Big Sky is also bull’s eye information wind loaded slopes are unstable (<strong><a href="https://www.mtavalanche.com/images/19/skier-triggered-slide-north-big-s…;) &nbsp;&nbsp;</p>

<p>Non-wind loaded slopes are also getting pushed to a dangerous level by the heavy new snow. Yesterday, skiers on the Throne in the northern Bridgers observed recent avalanche activity in the new snow and got unstable test results on a weak interface a foot below the surface (<strong><a href="https://www.mtavalanche.com/images/19/natural-activity-thethrone">photo…;). Today, human triggered slides breaking 1-2’ in depth on non-wind loaded slopes are likely.</p>

<p>For this reason the avalanche danger is rated <strong>CONSIDERABLE</strong> on all slopes.</p>

<p>If you get out and have any avalanche or snowpack observations to share, contact us via our <u><a href="https://www.mtavalanche.com/node/add/snow_observation">website</a></u&gt;, email (<u><a href="mailto:mtavalanche@gmail.com">mtavalanche@gmail.com</a></u&gt;), phone (406-587-6984), or Instagram (#gnfacobs).</p>

Upcoming Avalanche Education and Events

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

BOZEMAN

Today, March 2 and 3, Bozeman Split Fest, More info at www.bozemansplitfest.com.

March 6, 1-hr Avalanche Awareness, 6-7 p.m. at REI Bozeman.

Large Natural Avalanche- Knowles Peak

Knowles Peak
Out of Advisory Area
Code
SS-N-R2-D2-I
Elevation
7800
Aspect
N
Latitude
45.30490
Longitude
-110.54400
Notes

We received this report of an unusually large natural avalanche in the East Mill Creek drainage: " First time in 17 years we have had an avalanche come into our road. Natural, maybe from a point release that fractured new snow about 20 inches at the crown, propagated 50 yards, ran about 300 feet without stepping down, leaving about 5 foot deep debris. A new 2 inches is covering the debris that likely went during this afternoons warming."  Photo and comments: L. Watson

Number of slides
1
Number caught
0
Number buried
0
Number killed
0
Avalanche Type
Soft slab avalanche
Trigger
Natural trigger
R size
2
D size
2
Bed Surface
I - Interface between new and old snow
Slab Thickness
20.0 inches
Vertical Fall
300ft
Slab Width
150.00ft
Slab Thickness units
inches
Single / Multiple / Red Flag
Single Avalanche
Advisory Year

We received this report of an unusually large natural avalanche in the East Mill Creek drainage: " First time in 17 years we have had an avalanche come into our road. Natural, maybe from a point release that fractured new snow about 20 inches at the crown, propagated 50 yards, ran about 300 feet without stepping down, leaving about 5 foot deep debris. A new 2 inches is covering the debris that likely went during this afternoons warming."  Photo and comments: L. Watson

Out of Advisory Area, 2019-02-28

Natural avalanches near the Throne

The Throne
Bridger Range
Code
SS-N-I
Elevation
8000
Aspect
NE
Latitude
45.88230
Longitude
-110.95200
Notes

A skier reported seeing multiple recent avalanches near the Throne. They dug a pit and got propagating results failing at a density change within the new snow. From the email: "Around a foot of wetter, denser new snow (F+) slid on a dryer new snow interface (F-)". Photo: C. Kussmaul

Multiple Avalanches
Number caught
0
Number buried
0
Number killed
0
Avalanche Type
Soft slab avalanche
Trigger
Natural trigger
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

A skier reported seeing multiple recent avalanches near the Throne. They dug a pit and got propagating results failing at a density change within the new snow. From the email: "Around a foot of wetter, denser new snow (F+) slid on a dryer new snow interface (F-)". Photo: C. Kussmaul

Bridger Range, 2019-02-28