GNFAC Avalanche Forecast for Sun Jan 19, 2020
<p>Although not in our advisory area there were two people killed by avalanches yesterday, <a href="https://avalanche.state.co.us/caic/acc/acc_report.php?acc_id=736&ac… snowmobiler in Utah</a> and an <a href="https://avalanche.state.co.us/caic/acc/acc_report.php?acc_id=735&ac… climber in Colorado</a>. These were the ninth and tenth fatalities this month (<a href="https://avalanche.org/avalanche-accidents/">12 this season</a>). We are deeply saddened by each of these events. Incidents are frequent this time of year and we lose sleep over preventing more. Throughout the western U.S. the snowpack has buried weak layers that have been overloaded by storms since the start of 2020. Head out and have fun, but ride safe. Keep objectives mellow, constantly evaluate your exposure to avalanche terrain and commit to come home alive.</p>
<p>In southwest Montana we have seen natural and human triggered avalanches 15 of the last 18 days (<strong><a href="https://www.mtavalanche.com/avalanche-activity">activity log</a></strong>). Yesterday Doug visited a massive avalanche on Mt. Henderson near Cooke City. It was up to 15 feet deep and triggered by a snowmobiler on Thursday (<strong><a href="https://www.youtube.com/watch?v=VXVEIqSWvdY&list=PLXu5151nmAvSbcbVf…;). This and an avalanche on Buck Ridge a couple weeks ago (<strong><a href="https://www.mtavalanche.com/node/21453">details</a></strong>) are two of the three largest crowns Doug has seen in person (he’s been around for years, at least 25). Both were triggered by snowmobilers, and on Buck Ridge three people were caught and luckily uninjured.</p>
<p>Yesterday a snowmobiler triggered an avalanche in the Taylor Fork (<strong><a href="https://www.mtavalanche.com/images/20/snowmobile-triggered-slide-taylor…;), and a large natural avalanche broke from a cornice fall south of Saddle Peak (<strong><a href="https://www.mtavalanche.com/images/20/natural-cornice-triggered-deep-sl…;). Near West Yellowstone two separate groups were surprised that they could get stability tests to propagate on sugary snow deep in the snowpack.</p>
<p>Avalanche conditions are heightened and large avalanches can be triggered with severe consequences. These big slides are getting more difficult to trigger as weak layers get buried deeper, but as Doug says in his <strong><a href="https://www.youtube.com/watch?v=VXVEIqSWvdY&list=PLXu5151nmAvSbcbVf…;, “they will kill you”. If you go into avalanche terrain you have to collect a lot of data and be 99.9% sure of good stability. Large avalanches are possible to trigger and avalanche danger is MODERATE.</p>
<p>Yesterday there were three skier triggered avalanches reported in the northern Gallatin Range (<strong><a href="https://www.mtavalanche.com/node/21638">details</a></strong>, <strong><a href="https://www.mtavalanche.com/node/21655">details</a></strong>). One on Flanders Mountain was very large and took out the skin track of another group (<strong><a href="https://www.mtavalanche.com/node/21650">details</a></strong>). The snowpack in and near Hyalite was generally stable, but yesterday’s activity is a sign that recent wind-drifted snow has activated buried weak layers. Avalanches are possible to trigger on wind loaded slopes and they can break wide on buried persistent weak layers. On non-wind loaded slopes avalanches are less likely. Carefully evaluate the snowpack and terrain. Danger is MODERATE on wind loaded slopes and LOW on other slopes.</p>
<p>If you get out, please send us your observations no matter how brief. You can fill out an <u><strong><a href="https://www.mtavalanche.com/node/add/snow_observation">observation form</a></strong></u>, email us (<u><strong><a href="mailto:mtavalanche@gmail.com">mtavalanche@gmail.com</a></strong></u>), leave a VM at 406-587-6984, or Instagram (#gnfacobs).</p>
Upcoming Avalanche Education and Events
Our education calendar is full of awareness lectures and field courses. Check it out and plan to attend one or two: Events and Education Calendar.
COOKE CITY
Every Friday and Saturday, Snowpack Update and Rescue Training. Friday, 6:30-7:30 p.m. at the Soda Butte Lodge. Saturday anytime between 10-2 @ Round Lake.
BOZEMAN
January 20th from 4-8pm at Beehive Basin Brewery, join the YC and Big Sky Ski Patrols to support the Darren Johnson memorial fund. Darren was a ski patroller at the Yellowstone Club who was killed in an avalanche on January 19th, 2016. The memorial fund gives scholarships to send patrollers to the National Avalanche School.
Skier triggered small slide Mount Wheeler
From obs: "Skied into to a pillow of snow. I think it started as just sluff but then broke off an avalanche. It was not wide but the crown is estimated at 2 feet. It was not moving fast and I just dug into the bed surface and slowly moved out of it. I was the second skier. The first skiers track did not go as deep as mine. failed on weak facets at the base of a steep roll over."
Avalanche triggered by skiers on Flander's peak in Hyalite on 1/18/20. Nobody caught or buried, but they were surprised and it covered another groups skin track. Photo: J. Riedel
Avalanche triggered by skiers on Flander's peak in Hyalite on 1/18/20. Nobody caught or buried, but they were surprised and it covered another groups skin track. Photo: J. Riedel
Forecast link: GNFAC Avalanche Forecast for Sun Jan 19, 2020GNFAC Avalanche Forecast for Wed Jan 22, 2020
Snowmobile triggered in Taylor Fork
From obs: "2nd hand observation arrived at site about 5 minutes after slide. Triggered by sidehilling snowmobiler but was not caught up in it. looked approximately 50 ft wide 150 ft vertical. Did not appeared to be very deep."
From e-mail: "2nd hand observation arrived at site about 5 minutes after slide. Triggered by sidehilling snowmobiler but was not caught up in it... looked approximately 50 ft wide 150 ft vertical. Did not appeared to be very deep" Photo: P. Gish
Forecast link: GNFAC Avalanche Forecast for Sun Jan 19, 2020
Skiers triggered 2 large slides Flanders Mtn.
From Obs: "... Our party of two was ascending southwest on a rib with the intention of reaching the ridgeline. At 9800', the upper member of our party triggered a D2.5 with an approximately 100' crown immediately to our south. Crown height appeared 2-3' and the slide traveled approximately a distance of 2,000' and 500 vertical feet down mountain. Within a few seconds, we remote triggered to the north a D3 with an approximately 200' crown. Crown height appeared up to 7' at highest point and slide traveled approximately 300 vertical feet down mountain. The remote triggered slide started approximately 15-20 feet to the north of the location of the lower member of our party, who was approximately 30 vertical feet below the upper member of our party. After the slide the upper member of our party noticed a shooting crack at his elevation. Two skiers and one dog were ascending below us. They observed the avalanche and later mentioned that they were approximately 150 feet in distance from the toe of the remote triggered slide, which completely covered their skintrack. Nobody caught or buried."
From group that was below: "Finished a snow pit at 45.434589, -110.940957. Results were ECT-X, Aspect: 110 deg, Angle: 27 degrees, Depth: 90 cm, Weak layer was above melt/freeze at 60 cm, fist hardness above 62 - 67 cm. Then fairly cohesive newer snow 70 - 90 cm. Weak layer did not budge, even when levered with the shovel.
Knowing there was one party of two ahead of us, we continued to 45.434716, -110.94124 when they triggered slide above. It ran through one of the avalanche paths behind us, that we had crossed. We whooped to see if someone was the trigger and if they were ok, they yelled back all was ok. Our mistake was assuming the party ahead was taking, what we consider to be, the standard route up Flanders, not the subtle ridge that we figured was loaded by the month of west/sw winds We were wrong and were traveling below them but still were traveling in the older trees and not in slide paths, yet another example of why you follow protocol. Anyways I took a bunch of pics. Pin on map is about where they triggered it."
The crown of this snowmobiler triggered avalanche tapered to a thin slab. These thin areas of the slope are prime zones to trigger a slide from. Photo: GNFAC