17-18

GNFAC Avalanche Advisory for Thu Mar 15, 2018

Snowpack and Avalanche Discussion

<p>Overnight the Gallatin and Madison Ranges picked up 4-6” of snow totaling .4-.6” of SWE. This isn’t a huge amount of snow, but it is enough to increase the dry snow avalanche hazard. The new snow was deposited on a firm melt-freeze crust on all but north facing slopes. This will make dry loose avalanches (sluffs) possible in steep terrain. It’s also possible that skiers or riders could trigger small wind slabs in upper elevation terrain leeward to southwest winds. These problems won’t produce exceptionally large avalanches, but they could be hazardous in steep, high consequence terrain. Manage these problems by making smart and conservative terrain selections. Below freezing temperatures will eliminate the possibility of wet snow avalanches.</p>

<p>Today, human triggered slides are possible and the avalanche danger is rated <strong>MODERATE</strong>.</p>

<p>The mountains around Cooke City, West Yellowstone and the Bridger Range picked up 1-2” of high density snow. This will slightly improve riding conditions, but it won’t do much to elevate the avalanche danger. As temps drop below freezing today, the old snow surface on all but north facing slopes will be firm and locked up. Today, there won’t be much in the way of avalanche hazard other than large cornices. On Tuesday, I observed a few recent avalanches triggered by cornice failure in the mountains around Cooke City (<a href="https://youtu.be/kiUzoTR50MM"><strong>video</strong></a&gt;). Give cornices a wide berth along the ridgelines and limit your exposure time on slopes below (<a href="https://www.mtavalanche.com/images/18/watch-out-cornices-cooke-city"><s…;, </strong><a href="https://www.mtavalanche.com/images/18/cornice-triggered-avalanche-near-…;).</p>

<p>Today, generally safe avalanche conditions exist and the avalanche danger is rated <strong>LOW</strong>.</p>

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

Upcoming Avalanche Education and Events

Events and Education Calendar

LIVINGSTON

March 20, Beer for a Cause Night at Katabatic Brewing, 4-8p.m. A dollar from every pint will be donated to The Friends of the Avalanche Center.

This slide occurred on the steep, south facing slopes across from Bacon Rind in the southern Gallatin Range. Areas where the snowpack is thinner were heavily affected by above freezing temps earlier in the week. Fortunately, cooler temps over the weekend will reduce the potential for wet loose avalanches. Photo: N. Marion

Southern Gallatin, 2018-03-15

GNFAC Avalanche Advisory for Wed Mar 14, 2018

Snowpack and Avalanche Discussion

<p>Even though mountain temperatures will be above freezing today, cloud cover and wind will keep the snow surface cool enough to inhibit wet avalanches. Rain, however, is a different beast. The fist rain on a winter snowpack can quickly create widespread avalanches, so get out of the mountains if it rains today. Only the most diehard would stay anyway, avalanches or not.</p>

<p>Yesterday there were reports of wet, loose avalanches in all our ranges except Cooke City (<strong><a href="https://www.mtavalanche.com/images/18/wet-loose-avalanches-hyalite">pho… href="https://www.mtavalanche.com/images/18/goat-checks-out-wet-loose-avalanc…;). These will not be a danger today. Eric is in Cooke City and found good stability (<strong><a href="https://youtu.be/kiUzoTR50MM">video</a></strong&gt;). His main concern is cornices breaking (<strong><a href="https://www.mtavalanche.com/images/18/watch-out-cornices-cooke-city">ph…;, <a href="https://www.mtavalanche.com/images/18/cornice-triggered-avalanche-near-…;), which is also our #1 worry throughout the advisory area. Above freezing temperatures will make these large overhangs of snow structurally weak. A passing skier or sledder could trigger one and the danger is twofold: it can hurtle you off the ridge, and potentially trigger an avalanche on the slope below. Give all cornices a very wide berth.</p>

<p>The snowpack lacks widespread weak layers and is generally safe. It is still a good idea to dig and test the snow because avalanches can happen even during relatively stable times. A sledder last Wednesday triggered a slide on an isolated, steep slope near Hebgen Lake during a low danger (<strong><a href="https://youtu.be/yrjwILDWCJE">video</a></strong&gt;), which illustrates this point. For today, both the wet and dry snow avalanche danger is rated <strong>LOW</strong> provided it does not rain, which would spike the danger quickly.</p>

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

Upcoming Avalanche Education and Events

Events and Education Calendar

LIVINGSTON

March 20, Beer for a Cause Night at Katabatic Brewing, 4-8p.m. A dollar from every pint will be donated to The Friends of the Avalanche Center.

Large cornices are the main avalanche concern around Cooke City. Give these bus sized chunks of snow a wide berth along the ridgelines and avoid spending time on slopes below. Photo: GNFAC 

Cooke City, 2018-03-13