18-19

New snow avalanche near Mt. Blackmore

Mt Blackmore
Northern Gallatin
Code
SS-N-R2-D1.5-I
Elevation
8800
Aspect
N
Latitude
45.44680
Longitude
-110.98800
Number of slides
1
Number caught
0
Number buried
0
Avalanche Type
Soft slab avalanche
Trigger
Natural trigger
R size
2
D size
1.5
Bed Surface
I - Interface between new and old snow
Problem Type
New Snow
Images
New snow avalanche near Mt. Blackmore
Slab Thickness units
centimeters
Single / Multiple / Red Flag
Multiple Avalanches
Advisory Year
18-19

Skiers saw this natural avalanche near Mt. Blackmore on Saturday (11/24). Almost a foot of new snow fell and buried weak snow that formed on the surface of the snowpack during cold and dry weather. Be cautious of avalanches breaking at this weak interface for a few days and with the next storm. Photo: M. Staples

Avalanche Details: New snow avalanche near Mt. Blackmore
Forecast link: GNFAC Avalanche Forecast for Wed Nov 28, 2018
Northern Gallatin, 2018-11-25
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    • GNFAC Avalanche Forecast for Sat Nov 24, 2018

    Snowpack and Avalanche Discussion

    <p>The snowpack in the mountains is 3-4 feet deep near Bozeman, Big Sky and Cooke City, and 1-2 feet near West Yellowstone. Generally cold and dry weather since early November created a weak layer on the surface that is now buried below the last couple day’s snowfall. On Wednesday, Doug and I found this weak snow near Cooke City (<u><strong><a href="https://www.youtube.com/watch?v=M8ocv28K8eU">video</a></strong></u><u><…; <strong><a href="https://www.mtavalanche.com/images/18/weak-surface-snow">photo</a></str…;) and Eric found it in Hyalite (<u><strong><a href="https://www.youtube.com/watch?v=l0qvNwadm7Y&amp;list=PLXu5151nmAvRNl9ku…;). Where the snowpack is deeper, it is mostly strong and supportable below this weak layer.</p>

    <p>A few inches of snow and strong wind on Thursday was enough to form unstable conditions between the new snow and old, weak snow surface. The Big Sky ski patrol saw natural and human triggered avalanches during control work, and a skier in Hyalite reported natural avalanches that likely occurred Thursday (<u><strong><a href="https://www.mtavalanche.com/photos">photo</a></strong></u&gt;). More snow and strong wind today will rapidly add weight to now buried weak layers. Natural avalanches are possible as snowfall continues, and avalanches will be easy to trigger where snow is drifted into thick slabs near ridgelines and along edges of gullies.</p>

    <p>Be extra cautious today and avoid avalanche terrain. This includes lower angle terrain connected to steep slopes above. The snowpack has been fairly stable and trustworthy this season, but that may change quickly. Resist an urge to ride steep slopes based on previous stable snowpack data. Rapid loading today is a clear sign of decreasing stability. The best defense against avalanches today is conservative, low angle terrain selection.</p>

    <p>New this season, we added hyperlinks to the <u><strong><a href="https://www.mtavalanche.com/weather/wx-avalanche-log">Weather and Avalanche Log</a></strong></u> and a new Menu item &lt;<u><strong><a href="https://www.mtavalanche.com/avalanche-activity">Avalanches and SnowPits</a></strong></u>&gt; with information on avalanche activity and incidents.</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>

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