Skiers in Cooke City noted this natural storm slab that released on an east aspect at 9000' on March 9th. It broke 6" deep and 25' wide. Photo: B. Fredlund
Old snow was supportable on north aspects, nearly put on ski crampons at higher elevations. One small collapse in trees on approach from potosi. I guess the observation was very strong west-sw wind on ridges without much available to transport, enough to create an interface with the old snow and some small pockets. And did not see any naturals. We did get a good view of the slide path from last year near bell lake from the top of mine peak. I think my partner Aaron has a good pic of that. We did not dig any pits, managed terrain less than 30, run out etc. I have 360 video from summit, if you want see that, can email it.
<p>The mountains south of Big Sky through West Yellowstone picked up 4-6” of fresh snow equal to 0.4-0.5” of <a href="https://www.nrcs.usda.gov/wps/portal/nrcs/detail/or/snow/?cid=nrcs142p2… water equivalent</a>-SWE with 2-3” (0.2” SWE) in the Bridger Range through Big Sky. The depth will be greater in areas of drifted snow. As I explain in my <a href="https://www.youtube.com/watch?v=H8RLSPzsCtc"><strong>video</strong></a&…; from the Throne, the snowpack structure remains poor, but without significant snowfall, avalanches breaking on deeply buried weak layers are unlikely. The last human-triggered slab avalanches we know of occurred in the Madison Range nine days ago (<a href="https://www.mtavalanche.com/weather/wx-avalanche-log"><strong>avalanche… log</strong></a>). On Sunday, Alex and I went into the Maid of the Mist Basin to look at one of these old, deep-slab avalanches (<a href="https://www.youtube.com/watch?v=jHcGBFkyLbk&list=PLXu5151nmAvQDzKmH…;, </strong><a href="https://www.mtavalanche.com/images/21/deep-slab-arden-crown"><strong>ph…;). A skier or rider getting unlucky and hitting the trigger-point of one of these giant slides is a sobering thought. </p>
<p>Yesterday, skiers north of West Yellowstone dug two snowpits, got unstable results, and subsequently decided to stay in low-angle terrain. In Hyalite, a group ascending a steep chute noticed the snow depth change dramatically from their first pit, got unstable results in a second, and decided to pull the plug. These examples demonstrate how we should use snowpack assessment tools to find isolated areas of instability and adjust plans accordingly.</p>
<p>Today, human-triggered avalanches are possible in wind-loaded terrain. These slides will most likely be small, but be wary of the chance that a small slide or cornice collapse could trigger a larger avalanche. The avalanche danger is MODERATE on wind-loaded terrain and LOW on non-wind-loaded terrain. </p>
<p>The mountains around Cooke City received 3” of new snow equal to 0.3” of SWE. The snowpack lacks widespread buried weak layers and large slab avalanches are unlikely. Yesterday, riders east of Cooke City triggered a small, wind-loaded slope after cutting across it a couple of times (<a href="https://mtavalanche.com/node/24583"><strong>photos and details</strong></a>) and skiers west of Cooke City saw a large cornice collapse on a small slope (<a href="https://mtavalanche.com/images/21/cornice-drop-west-cooke"><strong>phot…;). These are good examples of how riders and skiers may still find isolated instability on low danger days and why safe travel protocols are vital on <em>all</em> days spent in avalanche terrain. Everyone should carry and be familiar with avalanche rescue gear and expose only one person at a time to avalanche hazards. Today, manage small slabs and loose snow avalanches by avoiding terrain that may elevate a slide’s consequences. The danger is LOW in the mountains near Cooke City.</p>
<p>If you get out, please send us your observations no matter how brief. You can submit them via our <a href="https://www.mtavalanche.com/node/add/snow_observation"><strong>website<…;, email (<a href="mailto:mtavalanche@gmail.com"><strong>mtavalanche@gmail.com</strong></a…;), phone (406-587-6984), or Instagram (#gnfacobs).</p>
The Friends of the Avalanche Center in partnership with the City of Bozeman put in a Beacon Park at Beall Park. It is located on the north side of the Beall building between N. Bozeman Ave. and the ice rink. Stop by with your
A rider cut across the slope a couple of times before triggering a small, but deep wind-slab.
A rider triggered this avalanche on Top of the World ride east of Cooke City on March 5th after cutting across the slope twice. Photo: K Sorensen
Cornice collapse (3/8) on a small slope West of Cooke City in Yellowstone National Park. Photo: J Logan
Dug a pit on the lower chute to the left at 1100 AM. We had a 140cm snow depth. ECTP 22 @ 30 cm and another one at ECTP30 @ 60cm. Slope was 28 degrees, east facing, elevation of 7500’, partly sunny area. Decided to stay in trees and lower angle slopes.
