18-19
Yellow Mountain Wet Slab
Two pits on the west side of Saddle peak. They were dug relatively close to each other, but subtle changes in aspect and elevation resulted in very different conditions. North-facing slopes remain cold and dry for now, while anything that is in the sun is transitioning to a springtime snowpack. Photo: GNFAC
Debris pile from the wet slab avalanche on Yellow Mtn. Photo: T. Vanyo
The debris gouged down to the ground along the track of this wet slab avalanche on Yellow Mtn. Photo: T. Vanyo
Start zone of a loose wet avalanche that triggered a wet slab on Yellow Mountain sometime in the last two days. Photo: T. Vanyo
GNFAC Avalanche Forecast for Tue Mar 26, 2019
<p>Avalanches are unlikely this morning, but will become more likely as temperatures rise and crusts break down. Yesterday, skiers triggered loose snow avalanches near Big Sky that while only involving the 3” of new snow, ran 400’ on the firm crust (<strong><a href="https://www.mtavalanche.com/images/19/loose-slides-new-snow">photo</a><…;). Near Cooke City, skiers found the new snow well bonded to the old snow surface. After a day of warm temperatures, this will be the case on most slopes. Still, as the day heats up, you could trigger small loose snow avalanches, particularly in areas that were cloudy yesterday but are sunny today. There may also be isolated pockets where you could trigger a wind slab avalanche. Shady slopes loaded by yesterday’s south and west winds are the most suspect. Be cautious of steep, wind loaded slopes if the snow surface feels stiff and is cracking under your feet or sled.</p>
<p>Yesterday, Doug and I found a dusting of new snow over a stout crust near Lionhead (<strong><a href="https://www.youtube.com/watch?v=C6qgTWYjj7U&list=PLXu5151nmAvRNl9ku…;). On shady slopes the lower snowpack is dry and stable. On sunnier slopes you’ll find unfrozen slush under the crust. As the crust melts this afternoon and becomes unsupportable on those sunny slopes, you could trigger a deeper wet avalanche (<strong><a href="https://www.youtube.com/watch?v=YvYdU9j52zM&index=2&t=0s&li…;). The timing of this breakdown will vary depending on aspect and cloud cover, but once you start sinking above your boot tops in wet snow it’s time to get off steep slopes. Pinwheels and rollerballs are warning signs that the snow surface is becoming wet and the danger is starting to rise.</p>
<p>Avalanche danger is <strong>LOW</strong> this morning and will rise to <strong>MODERATE</strong> this afternoon.</p>
<p>If you get out and have any avalanche or snowpack observations to share, contact us via our <a href="https://www.mtavalanche.com/node/add/snow_observation">website</a>, email (<a href="mailto:mtavalanche@gmail.com">mtavalanche@gmail.com</a>), phone (406-587-6984), or Instagram (#gnfacobs).</p>
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Long running loose slides in N. Madison
From instagram: "Easily triggered 3" soft slabs/loose snow slides. NW facing Northern Madison around 11,000' Ran 400' on s sun crust At least 3 intentionally triggered."
From instagram: "Easily triggered 3" soft slabs/loose snow slides. NW facing Northern Madison around 11,000' Ran 400' on sun crust. At least 3 intentionally triggered." Photo credit: B. Gill
Forecast link: GNFAC Avalanche Forecast for Tue Mar 26, 2019