On 2/4/23 we saw evidence of a large avalanche that broke during the avalanche warning last weekend in Going Home Chute, R3-D2.5 (see photos). It appeared to have run to the end of the runout zone and tipped over small trees. Photo: GNFAC
On 2/4/23 we saw evidence of a large avalanche that broke during the avalanche warning last weekend in Going Home Chute, R3-D2.5 (see photos). It appeared to have run to the end of the runout zone and tipped over small trees. Photo: GNFAC
On 2/4/23 we saw a crown of a large avalanche from earlier in the week on the west side of Beehive Basin, on an east facing slope around 8,800'. R3-D2, 2-3 feet deep, 150' wide. Photo: GNFAC
We observed some crowns from recent slides just south of the Flanders Peak east glade while touring up Flanders today. The snow was wind affected and slabby especially towards the ridges. No other signs of instability observed. We opted to stay in the trees and minimize exposure on the ski descent.
Our group toured up into Beehive Basin yesterday with the goal of skiing Peru and returning via Middle Basin. Our ascents and descents on the day showed signs of small pockets of wind slab instability (cracking and small pockets pulling loose), but nothing significant. On our final ascent up the backside of middle peak, there was a large shooting crack, maybe 30 feet in length, but we adapted our ascent route and were able to avoid further significant instabilities. Hand pits showed a thin 2" wind slab on our final ascent slope. Throughout the day we noticed a few old crown lines varying from 1 to 2' in depth and up to about 150' wide. These crown lines were on E, NE, NW and W aspects. The debris appeared to not be recent as it was covered with new snow and eroded, and some of the crown lines were filling in.
2/4/23: We dug a pit near the top of our ascent on a west aspect at 9,100'. HS was 160cm and we found surface hoar buried 55cm deep (105cm above ground). It did not propagate or easily break in our tests, but it was a clear stripe in the wall and may have contributed to the adjacent large avalanche last weekend. Photo: GNFAC
<p><span><span><span><span><span><span>Today a person can trigger avalanches that break 1-2 feet deep below recently wind-drifted snow or deeper on buried persistent weak layers. Recent human-triggered avalanches show what is possible, and are evidence that the snowpack needs more time to adjust to last weekend’s heavy snowfall. On Thursday and Friday near Big Sky, skiers triggered slides 1-2 ft deep on wind loaded slopes (</span></span></span></span></span></span><a href="https://www.mtavalanche.com/node/27963"><span><span><span><strong><span… 1</span></span></u></span></strong></span></span></span></a><span><span><span><span><span><span>, </span></span></span></span></span></span><a href="https://www.mtavalanche.com/node/27980"><span><span><span><strong><span… 2</span></span></u></span></strong></span></span></span></a><span><span><span><span><span><span>). On Friday near Cooke City, a skier was buried up to their waist in a slide on Fisher Mountain (</span></span></span></span></span></span><a href="https://www.mtavalanche.com/node/27986"><span><span><span><strong><span…;), and a rider triggered a small slide near Mt. Abundance (</span></span></span></span></span></span><a href="https://www.mtavalanche.com/node/27978"><span><span><span><strong><span…;).</span></span></span></span></span></span></p>
<p><span><span><span><span><span><span>Over the past two days I found buried surface hoar in the northern Gallatin Range (</span></span></span></span></span></span><a href="https://www.youtube.com/watch?v=LZ9aWLM7J2A&list=PLXu5151nmAvTi1DBS…;) and near Big Sky (</span></span></span></span></span></span><a href="https://www.youtube.com/watch?v=6zNtBZuvEWw&list=PLXu5151nmAvTi1DBS…;). Finding this buried weak layer is enough evidence to back off steep slopes until the snowpack has more time to adjust or “heal” after being loaded by heavy snow last weekend. As time passes without snow or wind-loading, more slopes become stable and there are fewer obvious signs of instability like collapsing or unstable snowpack test scores. However, the consequences and size of potential avalanches are large, and you do not want to risk finding a slope that is unstable. </span></span></span></span></span></span></p>
<p><span><span><span><span><span><span>Be extra cautious of wind-loaded slopes and carefully assess the snowpack for the presence of buried weak layers before riding or crossing steep slopes. If you plan to ride slopes steeper than 30 degrees, dig down 3-4 feet to be sure there are no concerning buried weak layers. If snow accumulates this afternoon, watch for fresh drifts that may be unstable and add weight to buried weak layers. Today the avalanche danger is MODERATE. </span></span></span></span></span></span></p>
<p><span><span><span><span><span><span>Please share avalanche, snowpack or weather observations via our</span></span></span></span></span></span><a href="https://www.mtavalanche.com/node/add/snow_obs"><span><span><span><span>…; </span></span></span></span></span></span><span><span><span><strong><span><u><span><span>website</span></span></u></span></strong></span></span></span></a><span><span><span><span><span><span>, email (</span></span></span></span></span></span><span><span><span><strong><span><span>mtavalanche@gmail.com</span></span></strong></span></span></span><span><span><span><span><span><span>), phone (406-587-6984), or Instagram (#gnfacobs).</span></span></span></span></span></span></p>
<p>In Island park a person can trigger avalanches that break 1-2 feet deep below wind-drifted snow or deeper on buried persistent weak layers. Snow is expected during the day, and danger will rise this afternoon if snowfall is heavy. Watch for fresh drifts that may be unstable and add weight to buried weak layers. Avoid freshly wind-loaded slopes and carefully assess the snowpack for the presence of buried weak layers before riding or crossing steep slopes.</p>
Thank you and great work to everyone who participated in this year’s King and Queen of the Ridge event. This year we set a fund-raising record of $31,626! We greatly appreciate the support from everyone who hiked, donated, and raised money for The Friends of GNFAC.
We toured up the ridge between Going Home Chute and Tyler's (below prayer flags). We saw evidence of a large avalanche that broke during the avalanche warning last weekend in Going Home Chute, R3-D2.5 (see photos). It appeared to have run to the end of the runout zone and tipped over small trees. We dug a pit near the top of our ascent on a west aspect at 9,100'. HS was 160cm and we found surface hoar buried 55cm deep (105cm above ground). It did not propagate or easily break in our tests, but it was a clear stripe in the wall and may have contributed to the adjacent large avalanche last weekend.
We dug a second pit over the ridge in Middle Basin on an east aspect at 9,200'. HS was 175cm and buried surface hoar was 80 cm deep (95cm above ground). It did not break or propagate in standard ECT, but did propagate cleanly after 4-5 extra hard hits. Old faceted layers deeper in the snowpack were generally strong in both pits.
We also saw a crown of a large avalanche from earlier in the week on the west side of Beehive Basin, on an east facing slope around 8,800'. R3-D2, 2-3 feet deep, 150' wide.
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Thanks to everyone who came out and supported the Friends of the GNFAC at this year's King and Queen of the Ridge at Bridger Bowl! Photo: GNFAC
