20-21

Three sledder triggered slides off Buck Ridge

Buck Ridge
Northern Madison
Code
SS-AMu-R2-D1.5-O
Elevation
9000
Aspect
SE
Latitude
45.17190
Longitude
-111.38000
Notes

During our field work today (12/29) we noted 3 avalanches:

1. On the north of the ridge before the Yellowmule Weather Station. It was small sized, wind-loaded and broke on facets. Guessing R2, D1.5.

2. 3rd Yellowmule we saw another small slide (R1, D1.5) on a wind-loaded slope that broke on facets.

3. We saw our third slide as soon as we turned down the hill from 3rd YM to MacAtee Basin. It was small (R1, D1) and broke to the ground on facets. It was a steep hill.

All three slides were likely triggered from the bottom on Sunday (12/27), were small and did not propagate far.

Number of slides
3
Number caught
0
Number buried
0
Avalanche Type
Soft slab avalanche
Trigger
Snowmobile
Trigger Modifier
u-An unintentional release
R size
2
D size
1.5
Bed Surface
O - Old snow
Problem Type
Persistent Weak Layer
Slab Thickness
40.0 centimeters
Vertical Fall
100ft
Slab Width
100.00ft
Weak Layer Grain type
Depth Hoar
Weak Layer grain size
4.00mm
Weak Layer Hardness
F
Slab Layer Grain Type
Precipitation Particles
Slab Layer Grain Size
1.00mm
Slab Layer Hardness
4F
Slab Thickness units
centimeters
Single / Multiple / Red Flag
Multiple Avalanches
Advisory Year

Independence mine rd/ Boulder river

Date
Activity
Snowboarding
Snowmobiling

Took a snowmobile up towards independence mine along with split boards. On our way up we felt the snowpack structure was poor so we stayed of steep slopes. We dug a pit on a sw facing slope at 8300’ and found the same weak facet layer on the ground with a facet, melt freeze crust, facet sandwich. We got a ctv, and a ectp11

Region
Out of Advisory Area
Observer Name
Elton Burns

Hungry

Date
Activity
Skiing

Well, that's why I call it trial and error programming.

Region
Bridger Range
Observer Name
Still not

Hungryier still

Date
Activity
Skiing

Well, that last one didn't work. Trying again.

Region
Bridger Range
Observer Name
Jimbo late

Hungry Horse

Date
Activity
Skiing

this should be date of MST 08: 15

24 hour format

Region
Northern Gallatin
Observer Name
jimbo early

Hungry horse breakfast

Date
Activity
Skiing

this should show the date in MST format. It should be for 8:15 this morning in this email.

Region
Out of Advisory Area
Observer Name
Jimbo date early

GNFAC Avalanche Forecast for Tue Dec 29, 2020

Snowpack and Avalanche Discussion

Moderate avalanche danger does not signify safe avalanche conditions and it is not a green light to enter steep terrain (</a><a href="https://avalanche.org/avalanche-encyclopedia/danger-scale/"><strong>ava… danger scale</strong></a>). This is especially true with weak snowpack structures like the one existing in the mountains from Lionhead through the Bridger Range. Yesterday, a skier triggered a small avalanche at base of the cliffs on the east face of Mount Blackmore, I triggered numerous collapses or “whumphs” with associated cracking in the Taylor Fork and others reported “monster whumphs” that shook the snow out of small trees at Bacon Rind (<strong><a href="https://mtavalanche.com/node/23439">avalanche details</a>, <a href="https://mtavalanche.com/node/23442">photo</a></strong&gt;). This adds to a growing list of avalanche activity and red flags since Christmas Day that includes several large avalanches triggered by ski patrols during avalanche mitigation work, small natural avalanches, whumphs and a large, skier triggered avalanche on Saddle Peak (<strong><a href="https://mtavalanche.com/avalanche-activity">avalanche activity log,</a></strong> <strong><a href="https://mtavalanche.com/node/23396">details</a></strong&gt;).</p>
Without new snow or wind-loading, the chances of triggering avalanches go down. People could ride and ski in steep terrain today and “get away with it” but this is not an advisable path to follow where persistent weak layers exist. </a>Watch our video from Lionhead to learn more about how we are thinking about the avalanche problem that exists in the mountains from West Yellowstone to Bozeman (<a href="https://www.youtube.com/watch?v=rWeNgK6_PTs&amp;feature=emb_title"><str…;

<p>Recent avalanche activity, cracking, “whumphing” and <a href="https://www.youtube.com/watch?v=Gk8W8nlUMpw">extended column tests</a> that propagate failure are all indicators to avoid steep terrain. Heed the signals mother nature provides. Today, human triggered avalanches are possible and the danger is rated MODERATE. </a>

<p>The foundation of the snowpack in Cooke City is generally strong. Human triggered avalanches are possible in steep terrain within recent and wind-drifted snow</a>. Numerous human and natural avalanches occurred during and immediately following last week’s snow and wind, but without widespread weak layers in the snowpack, these storm layers are stabilizing (<a href="https://youtu.be/Ava7FSUx9kY"><strong>video</strong></a&gt;, <strong><a href="https://mtavalanche.com/images/20/natural-avalanche-republic-crk">photo…;, <a href="https://mtavalanche.com/avalanche-activity">avalanche activity</a><a href="https://mtavalanche.com/avalanche-activity"&gt; log</a></strong>). We are not out of the woods yet as climbers outside Cooke City triggered a collapse yesterday, but we are on a good trend until the next storm arrives.</p>

<p>Search for instabilities within the upper few feet of the snowpack before entering steep terrain (<strong><a href="https://www.youtube.com/watch?v=Gk8W8nlUMpw">video</a></strong&gt;). If you find them, move to a different slope. Human triggered avalanches are possible and the avalanche danger in Cooke City is MODERATE.</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>website<…;, email (<a href="mailto:mtavalanche@gmail.com"><strong>mtavalanche@gmail.com</strong></a…;), phone (406-587-6984), or Instagram (#gnfacobs).</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: