20-21

Natural cornice fall nearly missed skiers, near Abiathar

Abiathar Peak
Out of Advisory Area
Code
C-N-R2-D2
Elevation
9500
Aspect
N
Latitude
44.97560
Longitude
-110.03100
Notes

From email: "My partners and I were booting up a couloir near abiathar and a large cornice fell and landed shortly below us in our bootpack. Spooked the hell out of us. We acknowledged the danger of those cornices before booting up, decided that it was probably safe due to relatively low winds and cool temps, and decided to go for it. In hindsight, we wonder if it was much warmer on the ridge near the cornice (we were in the shade), maybe we underestimated the ridgetop winds, or maybe we just got unlucky.

The cornice broke up a bit on some rocks before landing in our couloir, but there still vehicle sized chunks raining down. If we had been 5 minutes slower on the ascent we may have been killed."

Number of slides
1
Number caught
0
Number buried
0
Avalanche Type
Cornice fall
Trigger
Natural trigger
R size
2
D size
2
Problem Type
Cornice Fall
Slab Thickness units
centimeters
Single / Multiple / Red Flag
Single Avalanche
Advisory Year

Lewis creek

Date
Activity
Snowboarding

Went for a hike on a ridge line between Lewis creek and mill for hyalite creek. Saw the avalanche on a south/south east facing aspect around 9500’. I didn’t see how far it ran, but last year it broke loose and took out a lot of trees(video). Hard to tell how deep it broke but it broke pretty wide.

Region
Northern Gallatin
Observer Name
Elton

Alex Lowe Peak

Date
Activity
Skiing

We skied the Y Couloir on Alex Lowe Peak and gained the summit via the southwest ridge. The recent snow felt more consolidated but remained stable on both the ascent and descent. We were able to break off a small cornice onto a northern aspect (approximately 4ft long, 3ft high and 3ft in width) of the southwest ridge of Alex Lowe, and the resulting collapse did not trigger any significant sluff or failure of the slope below. The recent snow sluffed more readily as it was baked by the sun during the ascent, on the eastern aspect of the ridge. A ski cut in the couloir did not trigger significant sluff, but the snow was much more dense, throughout the entire couloir, than in days prior on similar aspects.

Region
Northern Gallatin
Location (from list)
Alex Lowe Peak
Observer Name
Erich Schreier

Small wet slides on Skyline Ridge

Skyline Ridge
Southern Madison
Code
WL-N-R1-D1
Elevation
9000
Aspect
S
Latitude
44.92050
Longitude
-111.23000
Notes

Three small wet slides on a south facing slope low on Skyline Ridge. Observed 3/13/21. Likely broke in the previous couple of days. Slides were 10-20 ft wide and ran less than 50 ft. Rocks and dirt visible on the slopes where they broke. 

 

Number of slides
3
Number caught
0
Number buried
0
Avalanche Type
Wet loose-snow avalanche
Trigger
Natural trigger
R size
1
D size
1
Slab Thickness units
centimeters
Single / Multiple / Red Flag
Multiple Avalanches
Advisory Year

Ross peak east meadows

Date
Activity
Skiing

Toured up to the east facing meadows below Ross peak. I dug a pit on an east aspect at 7750’. HS125cm. I did an extended column test and got the following results: ECTN22 @80cm, Q1. No propagation. 0-38 was faceted crystals, 39-92 pencil slab, 93-113 fist slab and 114-125 was soft dry snow. In the top 5cm of the snowpack there were near surface facets. I observed some surface hoar on wind/sun protected aspects but it is not widely distributed, and was not present where I dug my pit. It was windy up there and snow was being transported along ridgetops. I did not see any wet avalanches, but the snow down in the brackett creek drainage was very mushy on my way back to the car.

Region
Bridger Range
Location (from list)
Ross Peak
Observer Name
Nicholas Salsburg

GNFAC Avalanche Forecast for Sat Mar 13, 2021

Snowpack and Avalanche Discussion

<p>As temperatures warm and the snow melts in town, it’s a natural inclination to shift our focus towards spring and wet snow avalanches. But don’t forget, the lower snowpack on most slopes remains dry. The weak layers that formed last fall are still lurking down there <a href="https://www.youtube.com/watch?v=8Q4gTjESoq0"><u>(</u><strong><u>Teepee Basin video</u></strong></a>). While these weak layers haven’t gained much strength, without recent loading you are unlikely to trigger an avalanche on them. Use safe travel practices to minimize the consequences if you do: always carry rescue gear, go one at a time in avalanche terrain, and watch your partners from a safe spot (<a href="https://youtu.be/gPWSDAr-K1Q"><strong><u>travel advice video</u></strong></a>).</p>

<p>Although temperatures will be a few degrees warmer than yesterday, increasing wind will help keep wet snow problems in check on most slopes. Still, be on the lookout for wet snow on sunny slopes as the day heats up, particularly lower elevation slopes protected from the wind. As crusts break down, if you’re sinking more than ankle deep into wet snow, it’s time to move off steep slopes before you trigger a wet slide. These slides will generally be small, but on isolated slopes where the snowpack is saturated, wet slides could gouge to the ground or break as wet slabs (<a href="https://www.youtube.com/watch?v=l5LfdUsd0Wk"><strong><u>Specimen creek video</u></strong></a>).</p>

<p>Yesterday, skiers in the northern Bridger Range stopped during their ascent, dug, and got quite unstable test results (ECTP13). They backed off their objective and headed back to the car. This is an appropriate mindset during Low&nbsp;danger. Making more ambitious goals is reasonable, but keep searching for signs of instability and be ready to back off if you find them.&nbsp;</p>

<p>Large avalanches are unlikely and the avalanche danger LOW.</p>

<p>&nbsp;</p>

<p>While conditions are generally stable in the mountains around Cooke City, there are some small and/or isolated concerns. Several small slab avalanches were reported after the last snowfall and while they will mostly have stabilized, you might still be able to trigger a similar slide (<a href="https://www.mtavalanche.com/images/21/meridian-peak-avalanche"><strong>…;, <a href="https://www.mtavalanche.com/images/21/storm-slab-cooke-city"><strong><u…;). Triggering small loose wet avalanches will also be possible as the day warms up (<a href="https://www.mtavalanche.com/images/21/skier-triggered-loose-snow-slide-…;). We’ve had reports of small sluffs running long distances over firm crusts.</p>

<p>The avalanche danger is rated LOW.&nbsp;</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><u>websi…;, email (<a href="mailto:mtavalanche@gmail.com"><strong><u>mtavalanche@gmail.com</u></str…;), phone (406-587-6984), or Instagram (#gnfacobs).</p>

<p>&nbsp;</p>

Upcoming Avalanche Education and Events

See our education calendar for an up-to-date list of all local classes. Here are a few select upcoming events and opportunities to check out:

March 20, 5:30 p.m., Snowpack Update for Bozeman Splitfest, online Link to Join HERE

From email on 3/12/21: "...silver creek up to the saddle of Meridian in the NP yesterday. ... It was on the S aspect at 9,500ft of the shoulder that takes you up to the steep trees W of Meridian. It must have occurred in the last 24-48hrs due to not much snow had fallen since the avalanche occurred. It ran out down into the trees below. ... The crown looks to be over a foot deep, and the length must have been 50ft"

Photo: P. Whitmire

Cooke City, 2021-03-13