17-18
Reas Peak Avalanche Fatality _2
On the afternoon of Saturday, January 20, four snow bikers (motorized) were riding southeast of Reas Peak (9,298’) in the Centennial Range in Idaho. The group was riding along a trail near a creek bed below 500-700’ high slopes that were greater than 35 degrees steepness. Two bikers rode up 15’ from the bottom of the slope when it released, catching and burying one. The group had rescue gear and located the victim quickly. The victim’s head was 6’ from the surface and CPR was initiated but unsuccessful.
GNFAC Avalanche Advisory for Wed Jan 24, 2018
Snowpack and Avalanche Discussion
<p>Eric and I rode into Lionhead yesterday to check on snow stability and were pleased at the strengthening that’s been taking place (<strong><a href="https://youtu.be/nQ5ZZBJLC-4">video</a></strong>) since Alex’s visit on Saturday during the avalanche warning (<a href="https://youtu.be/y8O0iWplhS0"><strong>video</strong></a>). The snowpack is getting stronger and we saw no recent avalanches nor collapses, and our snowpits revealed 5’ of snow depth with improving stability test scores. However, this area has a poor snow structure (weak layers underlying denser slabs) and it’s possible to trigger an avalanche 2-4’ deep on weak, sugary facets near the ground, which is why Eric and I gave runout zones a wide berth. Additionally, it snowed 3’ since Friday and strong southwest winds are currently loading slopes that could avalanche naturally. For today, the avalanche danger is <strong>CONSIDERABLE</strong> on wind-loaded slopes and <strong>MODERATE</strong> on all other terrain.</p>
<p>Throughout our advisory area southwest winds are blowing strong at all elevations, not just the ridgelines and loading will occur in gullies and other fetches mid-slope. Yesterday, drifts were reported to be 1-2’ thick and today they’ll be even meatier and easily triggered. Over the weekend we had two skiers caught in the Bridger Range when they triggered wind-loaded slopes, one on Naya Nuki after a failed ski cut resulted in an 800’ ride, and another smaller avalanche on the Throne (<a href="https://www.mtavalanche.com/images/18/skier-triggered-wind-slab-throne"…;). Wind-loaded slopes were also triggered in Taylor Fork (<a href="https://www.mtavalanche.com/images/18/small-avalanche-wind-loaded-slope…;) and natural avalanches were seen outside Cooke City (<a href="https://www.mtavalanche.com/images/18/natural-avalanche-mt-abundance"><…;, <strong><a href="https://www.mtavalanche.com/images/18/avalanches-mt-hornaday-ynp">photo…;).</p>
<p>In addition to wind slabs, weak, sugary snow 1-2’ off the ground is a concern. This layer broke in one of my snowpits in Taylor Fork on Sunday (<a href="https://www.youtube.com/playlist?list=PLXu5151nmAvQSYtIfyQP-gMYrlfja6Ls…;), but not in others. The spatial variability between weak and strong slopes in close proximity to one another can be confusing. This is why we recommend digging and testing before getting into avalanche terrain. </p>
<p>For today, strong wind is creating a <strong>CONSIDERABLE</strong> avalanche danger on wind-loaded slopes. All other slopes have a <strong>MODERATE</strong> avalanche danger.</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>, email (<a href="mailto:mtavalanche@gmail.com">mtavalanche@gmail.com</a>), phone (406-587-6984), or Instagram (#gnfacobs).</p>
AVALANCHE FATALITY REPORT: Reas Peak, Centennial Range, 20 January
On the afternoon of Saturday, January 20, four snow bikers (motorized) were riding southeast of Reas Peak (9,298’) in the Centennial Range in Idaho. The group was riding along a trail near a creek bed below 500-700’ high slopes that were greater than 35 degrees steepness. Two bikers rode up 15’ from the bottom of the slope when it released, catching and burying one. The group had rescue gear and located the victim quickly. The victim’s head was 6’ from the surface and CPR was initiated but unsuccessful.
A couple of big avalanches observed on Mt. Hornaday (in Yellowstone Park). These avalanches occurred on S, SE aspects around 9,100', most likely last Friday (1/19). Photo: B. Fredlund
GNFAC Avalanche Advisory for Tue Jan 23, 2018
Snowpack and Avalanche Discussion
<p>Anywhere from 5-10” of low density snow fell around West Yellowstone. Winds are gusty and strong enough to form wind slabs. The snowpack in this area is weak and unstable. The new snow does not weigh much (.3” <a href="https://www.nrcs.usda.gov/wps/portal/nrcs/detail/or/snow/?cid=nrcs142p2… water equivalent</a>), but it’s enough to discount any gains in strength that were made in the last couple days. Alex had collapsing and cracking on Saturday, the same day a motorized snow biker was killed 15 miles to the west, near Island Park, on Reas Peak (a synopsis is at the end of the advisory).</p>
<p>Avalanches may break 2-4’ deep on sugary facets. Alex explains the snowpack structure in his <a href="https://youtu.be/y8O0iWplhS0"><strong>video</strong></a>. To sum up, cracking, collapsing, new snow and wind, avalanches and deaths, are evidence of dangerous conditions. If three avalanche fatalities in three weeks doesn’t get your attention, I’m not sure what will. Human triggered avalanches are likely today and the danger is rated <strong>CONSIDERABLE</strong>.</p>
<p>In the last 24 hours the mountains picked up low density, cold smoke powder (3-5%; .2-.4” of <a href="https://www.nrcs.usda.gov/wps/portal/nrcs/detail/or/snow/?cid=nrcs142p2…;), that will blow into 1-2’ thick drifts at the slightest breeze. On Saturday, in the Bridger Range, a skier was carried 800’ when he triggered a wind-loaded slope on the southeast face of Naya Nuki. On Sunday, a skier and his dog were caught (yes, the dog is ok) in a small 50’ wide wind-loaded zone on the Throne (<a href="https://www.mtavalanche.com/images/18/skier-triggered-wind-slab-throne"…;). Other reports also involved wind-loaded slopes being triggered at Fairy Lake (<a href="https://www.mtavalanche.com/images/18/fairy-lake-wind-slab"><strong>pho…;) and Taylor Fork (<a href="https://www.mtavalanche.com/images/18/small-avalanche-wind-loaded-slope…;), and a large natural slide on the east face of Mt. Abundance near Cooke City (<a href="https://www.mtavalanche.com/images/18/natural-avalanche-mt-abundance"><…;) and other naturals on Barronette (<strong><a href="https://www.mtavalanche.com/images/18/west-barronette-slide">photo</a><…;). Today, new snow and wind are building wind slabs which will be sensitive to triggering.</p>
<p>Deeper in the snowpack is a layer of weak, sugary snow located 1-2’ off the ground. I found this layer in Taylor Fork on Sunday (<a href="https://www.youtube.com/playlist?list=PLXu5151nmAvQSYtIfyQP-gMYrlfja6Ls…;) when it broke in my stability test (ECTP 24). Conditions are variable and some slopes are stable while others are not, a common occurrence since the snowpack does not strengthen equally. This is why we do stability tests.</p>
<p>New snow and wind are creating a <strong>CONSIDERABLE</strong> avalanche danger on wind-loaded slopes. All other slopes have a <strong>MODERATE</strong> avalanche danger.</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>, email (<a href="mailto:mtavalanche@gmail.com">mtavalanche@gmail.com</a>), phone (406-587-6984), or Instagram (#gnfacobs).</p>
AVALANCHE FATALITY REPORT: Reas Peak, Centennial Range, 20 January
On the afternoon of Saturday, January 20, four snow bikers (motorized) were riding southeast of Reas Peak (9,298’) in the Centennial Range in Idaho. The group was riding along a trail near a creek bed below 500-700’ high slopes that were greater than 35 degrees steepness. Two bikers rode up 15’ from the bottom of the slope when it released, catching and burying one. The group had rescue gear and located the victim quickly. The victim’s head was 6’ from the surface and CPR was initiated but unsuccessful.