18-19

Above freezing temps and direct sunshine are creating unstable conditions on steep sun-exposed slopes. This problem is most common in steep rocky terrain or areas with a shallow and weak snowpack. Move to shadier aspects or away from steep terrain if point releases are occurring. Photo: GNFAC 


Forecast link: GNFAC Avalanche Forecast for Thu Mar 21, 2019GNFAC Avalanche Forecast for Fri Mar 22, 2019
Northern Madison, 2019-03-20
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    • GNFAC Avalanche Forecast for Wed Mar 20, 2019

    Snowpack and Avalanche Discussion

    <p>My hackles are up. Wet avalanches are on my radar. Yesterday, I saw large wet loose slides in Gallatin Canyon that gouged to the dirt on south facing slopes. In Bacon Rind the low elevation snowpack was fully moist and broke twice in my stability tests (ECTP 12 and 13) on facets near the ground (<u><strong><a href="https://www.youtube.com/watch?v=O_M2PnMldm0&amp;list=PLXu5151nmAvRNl9ku…;). This was unexpected. Slopes that are sunny, wet, shallow (3-4 feet) and faceted are the most susceptible to avalanching. Most low elevation, southerly facing slopes fit this bill. This is the <em>first time</em> water has hit facets near the ground, and the snowpack does not like <em>firsts</em>. Rapid change creates instability. Wet loose avalanches can gouge to the dirt (<u><strong><a href="https://www.mtavalanche.com/images/19/wet-loose-avalanches">photo</a></…;), and wet slabs could propagate across a slope. Slopes will start out with a thick, frozen crust that will warm and melt by late morning, a process Ian describes in this <u><strong><a href="https://www.youtube.com/watch?v=BahTTtR9lAA&amp;t=0s&amp;list=PLXu5151n…; from Cooke City.</p>

    <p><u>A word of caution</u>: Low elevation, south facing slopes are on the commute to and from higher, dryer terrain. These slopes will be especially dangerous during exit later in the afternoon when we may not be the most attentive.</p>

    <p>During my tour I dug on an east facing slope at 8,900 feet.&nbsp; A 3” thick ice crust capped the slope and under it the snow was dry and cold (-5C, 20 cm down). On slopes that are not getting very wet from sun, avalanches are unlikely. For today, the avalanche danger will start out LOW but rise to MODERATE as the sun and temperatures climb.&nbsp;</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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