21-22

Identifying snow crystals in the layer that failed at the crown of the avalanche on Ski Hill. The avalanche broke on weak, faceted crystals near the surface. Photo: GNFAC

Lionhead Range, 2022-02-08

GNFAC Avalanche Forecast for Tue Feb 8, 2022

Snowpack and Avalanche Discussion

<p>Heavy snowfall last weekend resulted in both human-triggered and natural avalanches in the mountains around Cooke City. This instability will be slow to stabilize because of a persistent weak layer of sugary facets and feathery surface hoar buried 18-24” deep (<a href="https://www.mtavalanche.com/images/22/buried-surface-hoar-layer-ynp-nea…;). On Sunday, a small avalanche remotely triggered by a group of riders broke on the opposite side of the small hill they were playing on, showing the weak layer’s dangerous ability to communicate failure widely (<a href="https://mtavalanche.com/images/22/remote-triggered-avalanche-near-goose…;). Yesterday, Alex rode around Cooke City and continued to get unstable test results, warning that conditions are going to stay unstable for a while (<a href="https://www.youtube.com/watch?v=MnPzHXhqay0&amp;list=PLXu5151nmAvT1nrM2…;). Look at the <a href="https://mtavalanche.com/photos"><strong>photos page</strong></a><strong> </strong>on our website to see many images of avalanches in Cooke City from the last several days.</p>

<p>Dangerous, human-triggered slides remain possible and the danger is MODERATE. The danger will rise to CONSIDERABLE on wind-loaded slopes if forecasted winds begin loading snow into fresh drifts. Keep it simple by employing careful route finding and conservative decision-making to avoid avalanches today.</p>

<p>The snowpack in the Bridger, Madison and Gallatin Ranges and in the Lionhead Ridge area is mostly stable. While large avalanches are unlikely, there are two isolated problems. The first is a layer of weak snow buried 6-18” deep and the second is recent drifts created by strong winds. Two relatively small, snowmobile-triggered avalanches on Sunday show that isolated pockets of instability remain (<a href="https://mtavalanche.com/node/25767"><strong>details and photos</strong></a>). Unfortunately, one of these relatively small avalanches ended in tragedy when a rider was partially buried against a terrain trap of trees (<a href="https://mtavalanche.com/node/25766"><strong>limited details and photos</strong></a>). While this weak layer is widespread across the Lionhead area and in the Gallatin, Madison and Bridger Ranges, there is generally not enough of a slab on top of it to avalanche.</p>

<p>The wind has blasted the Northern Madison, Northern Gallatin and Bridger Ranges for days. Recent wind drifts are small and mostly stable but look for signs that small slabs could still break on underlying weak layers and consider terrain features that would make small slides unforgiving (<a href="https://www.mtavalanche.com/images/22/northern-bridger-unstable-pit-res…;).</p>

<p>Be on the lookout for these localized problems and hedge your bets by following safe travel protocols. Avalanches are unlikely and the danger is LOW.</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>

Upcoming Education Opportunities

See our education calendar for an up-to-date list of all local classes. Here are a few select upcoming

February 10th, Forecaster Chat at Uphill Pursuits, “Beyond the Beacon” with GNFAC Forecaster Dave Zinn

Every Saturday near Cooke City, 10 a.m.-3 p.m. FREE snowpack update and transceiver/rescue training. Stop by for 20 minutes or more at the Round Lake Warming Hut.

A group of riders snapped a photo of this avalanche on Sunday. The slide isn't huge but it would be highly consequential in the treed terrain were trauma is a real possibility. Photo: A. Bertolino

Cooke City, 2022-02-08

A group of snowmobilers reported triggering this small avalanche from the backside of the rollover on Sunday. Triggering an avalanche from a long distance away is a clear sign of an unstable snowpack. Photo: A. Bertolino

Cooke City, 2022-02-08