From obs: "Southerly aspects had significant sluffing on the crust interface" Photo: M. Zia
21-22
From obs: "Observed a D1.5 natural on the N side of Maid of the Mist, photo attached. Looked like the upper pocket slid, then triggered the lower slope. ~75m crown line on the lower slope, depth looked like between 20-40cm. Upper pocket, hard to tell with limited viz." Photo credit: M. Zia
Avalanche Details: Natural Avalanche in Maid of the Mist
Forecast link: GNFAC Avalanche Forecast for Mon Mar 21, 2022
Northern Gallatin, 2022-03-20
Forecast link: GNFAC Avalanche Forecast for Mon Mar 21, 2022
Cornice Triggered Avalanche Republic Creek
Republic Creek
Cooke City
Code
SS-NC-R2-D2-O
Aspect
N
Latitude
44.98550
Longitude
-109.94100
Notes
Skiers spotted this natural avalanche on a north-facing slope in Republic Creek
Number caught
0
Number buried
0
Avalanche Type
Soft slab avalanche
Trigger
Cornice fall
R size
2
D size
2
Bed Surface
O - Old snow
Slab Thickness units
centimeters
Single / Multiple / Red Flag
Single Avalanche
Advisory Year
Collapsing on NE aspect in Bear Basin
Bear Basin
Northern Madison
Code
Latitude
45.34530
Longitude
-111.37500
Notes
From obs: "We were one basin north of Bear basin on the NE ramp of Bear Peak (10400'). We were on an NNE aspect of the ramp taking off our skis to dig a pit when we noticed how rotten the snow was, boot pen was immediately up to our waste. My partner noticed a subtle collapse and a couple of seconds later we both felt and audibly heard a larger collapse. There were a few shooting cracks about 5-8 feet up the slope from us and arcing about 10 feet across the slope. We gingerly put our skis back on and traversed down and away from to a low-angle bench.
Digging hasty hand pits and probing with our poles we continued to notice hard crusts and slabs with weak snow beneath them on E and NE aspects protected from the sun but less so on anything slightly south-facing or west. During a quick column test on a SE aspect at about 10,200', the result was CT14."
Number caught
0
Number buried
0
Slab Thickness units
centimeters
Single / Multiple / Red Flag
Red Flag
Advisory Year
GNFAC Avalanche Forecast for Sun Mar 20, 2022
Snowpack and Avalanche Discussion
<p>Heavy snowfall this morning followed by moderate northwest wind will make human triggered avalanches likely on wind-loaded slopes and possible on non-wind loaded slopes today. A person can trigger large, dangerous avalanches that break 1-3 feet deep on buried weak layers, or fresh drifts of snow up to a foot deep.</p>
<p>Over the last week avalanches were triggered by skiers near Cooke City (<a href="https://www.mtavalanche.com/images/22/skier-triggered-slide-mount-abund…;), Big Sky and in Hyalite (<a href="https://youtu.be/f6wLR3tLNa8"><strong>Wyoming Bowl video</strong></a>, <a href="https://www.mtavalanche.com/node/26199"><strong>Mt. Blackmore slide details</strong></a>), by snowmobilers near Buck Ridge (<strong><a href="https://www.mtavalanche.com/images/22/rider-triggered-avalanche-near-mu…;) and broke naturally throughout the forecast area (<strong><a href="https://www.mtavalanche.com/avalanche-activity">activity log</a></strong>). Yesterday Ian and I rode around Lionhead near West Yellowstone and noted very weak snow buried about a foot deep that was not yet unstable, but today’s snow could create a widespread instability (<strong><a href="https://www.youtube.com/watch?v=xc770oqXMsE&list=PLXu5151nmAvT1nrM2…;). We have already seen these weak layers become unstable with snow earlier in the week and cause avalanches near Cooke City, the Bridgers, Hyalite and Big Sky, and today’s snow will cause more.</p>
<p>Avoid slopes with fresh drifts of snow. If you plan to ride or travel in steep terrain, first carefully assess the snowpack on safe, low-angle slopes similar to those you plan to ride. Dig down a couple feet to look for and test buried weak layers. Stay off steep slopes if you see natural avalanches or experience cracking and collapsing of the snowpack under your feet, skis or snowmobile. Avalanches breaking on persistent weak layers can be triggered from flatter terrain near or below steep slopes, so pay attention to what is above you and be cautious crossing underneath steep slopes.</p>
<p>Today, avalanche danger is rated CONSIDERABLE on wind-loaded slopes and MODERATE on non-wind loaded slopes.</p>
<p>If you get out, please send us your observations no matter how brief. You can submit them via our website, email (mtavalanche@gmail.com), phone (406-587-6984), or Instagram (#gnfacobs).</p>
From email 3/20/22: "Visible from ridge dividing Republic and Wyo Creeks. N facing. Cornice drop with a step down 1/2way down?" Photo: N. Stayner