23-24

Zimmer Creek Avalanche

Date

Sun, 01/21/2024 - 12:15

Activity

Skiing

Remote triggerd a D1 Avalanche from about 150' away. Crown was 1-2' deep. The debris ran onto an apron that was shared with a larger slope which subsequently triggered a larger D2 Avalanche that was about 100' wide with a 3'-4' crown. Lots of cracking and collapsing of the snow pack all day and remote triggered a few other smaller slopes during the day. The snowpack is very sensitive out there right now.

Region

Cooke City

Location (from list)

Zimmer Creek

Observer Name

Ben Zavora

Natural avalanches in Truman Gulch

Date

Sun, 01/21/2024 - 11:10

From BBSP:

They noted 2 or 3 natural slides that occurred last night on the backside of Bridger Bowl in Truman Gulch.

Region

Bridger Range

Location (from list)

Truman Gulch

Observer Name

Doug Chabot

Skier triggered on Saddle Peak

Date

Sun, 01/21/2024 - 10:45

Activity

Skiing

From GCSAR and Bridger Bowl Ski Patrol:

A skier triggered a slide descending the skyline/nose of Saddle Peak. No one was caught. It initially triggered at the first rock band, then pulled out much wider at the second rock band. The skier was on his second lap was the third set of tracks on the peak. All tracks were accounted for and a beacon search of the debris came up empty.

Depth was described as "full depth" (2-3') and running on the depth hoar.

Crown was 80' wide on the first horizontal band and 500+' on the second. The lower crown wrappped around the ridge out of view.

Region

Bridger Range

Location (from list)

Saddle Peak

Observer Name

Doug Chabot

New snow on top of loose snow

Date

Sun, 01/21/2024 - 10:30

Activity

Skiing

Quick skin up to the top of the far south Telemark Meadows point. Lots of thumping in the flat untracked areas up the the top. Cracks not easily seen as dense snow covered them as they spread. Quick Pit, 45cm depth. About 4" of new heavy snow on top of yesterdays sun drenched layer. Below lots of loose facets and 2 distinct frozen layers buried 15-20cm below surface to the ground. 0.3" SWE last night. 24 degree slope, south facing. Air and Snow 30F.

Region

Southern Madison

Location (from list)

Telemark Meadows

Observer Name

Jon Budreski

Remotely Triggered Avalanche Below Hyalite Peak

Date

Sun, 01/21/2024 - 10:05

Activity

Skiing

My partner and I remotely triggered a persistent slide on an East facing slope at 9350ft. The slide ran off the Evil Twin ridge, just below the large main summer trail bowl of Hyalite Peak. My partner and I were spaced out ~50ft when we both felt and heard a large whumpf. We looked up and saw the avalanche slide, but were both out of harms way from the path. The starting zone was ~400ft above us and the slide ran ~500ft in total length. The crown was just over 2ft deep at its max and 150ft+ wide. The were signs of recent wind loading as we approached the bowl prior to the slide. We did not observe any other avalanches while we were out. Got a couple nice turns in the approach meadows on our way out.

Region

Northern Gallatin

Location (from list)

Hyalite Peak

Observer Name

Tucker Hoefler

Poor Structure and Variable Depth/Conditions in Hellroaring

Date

Sat, 01/20/2024 - 04:10

Activity

Skiing

Spent a day digging out the Hut in the Centennial Saturday 1/20. Our hasty pit, 20 deg. SW aspect at 7,000’ about 1/2 way into the hut showed 75 cm snow depth and various sized facets to a depth of 45 cm from the ground overlain by new snow. The structure was poor, and weak but we did not observe propagation in an ECT. Snow surfaces were damp on all aspect that we touched below 8,000’, pin wheel rollers on many steep slopes could be seen near the creek. Plenty of collapsing and “whumfing” on the way in kept us wary. Snow depths below 7,000 feet were as shallow as I have seen in 10 years operating the hut.

Region

Island Park

Location (from list)

Centennials - Montana

Observer Name

Sam Hansen

Avalanche on SE bowl of Flanders

Date

Sat, 01/20/2024 - 14:42

Activity

Skiing

Snow was heavy and glopping on our way up to the basin. Our plan remained the same all day - ski the skiers left trees of the SE bowl in Flanders. Once in the Alpine, lack of snow in the area led to slow, rock hitting skiing, one of our partners took a turn a bit more right of original ski line. I was waiting up higher in a safe position, and watched as he turned into the bowl, a remote triggered avalanche ripped out above him. He was fast to reach a safe position in the trees by the time the avalanche finished its ride. The photo shows the 3 ski tracks, and the most left one is what remote triggered above.

Region

Northern Gallatin

Location (from list)

Flanders Creek

GNFAC Avalanche Forecast for Sun Jan 21, 2024

Snowpack and Avalanche Discussion

Avalanche conditions are very dangerous. Large avalanches are easy for a person to trigger, and almost certain on wind-loaded slopes. Steady moderate winds are drifting new and recent snow into thicker slabs on top of a snowpack that has been collapsing and avalanching for the past two weeks (<a href="https://www.mtavalanche.com/weather/wx-avalanche-log"><span… and avalanche log</a>, <a href="https://www.youtube.com/watch?v=74rb5HCvbsE">… City video</a>, <a href="https://www.mtavalanche.com/node/30037"><span… photos</a>, <a href="https://www.mtavalanche.com/node/30046"><span… Fork photos</a>). Yesterday, skiers near Cooke City described widespread instability with multiple large, loud 100’ wide collapses (<a href="https://www.mtavalanche.com/node/30098"><span…;), and one group triggered an avalanche from relatively flat terrain when they stepped off the skintrack (<a href="https://www.mtavalanche.com/node/30103"><span…;). In the southern Madison Range, riders saw natural and rider triggered slides (<a href="https://www.mtavalanche.com/node/30076"><span… and photos</a>), and skiers reported large collapses.

Avalanches have been triggered from flat terrain connected to steep slopes, breaking on weak layers of surface hoar and facets, 1-2 feet deep and up to hundreds of feet wide. Find safe terrain that is less than 30 degrees steep and not connected to steeper terrain above. The avalanche danger is HIGH on wind-loaded slopes and CONSIDERABLE on all other slopes in the mountains near Cooke City, West Yellowstone and Island Park.

Near Big Sky and in the Bridger Range human-triggered avalanches are likely on wind-loaded slopes. Since yesterday these mountains received 2-5” of new snow (0.3”-0.5” snow water equivalent), and moderate winds drifted this snow into thicker slabs on top of a very weak snowpack. Yesterday, in Beehive Basin skiers triggered a large cornice and hard slab avalanche from a flat ridge above (<a href="https://www.mtavalanche.com/node/30094"><span…;), and in the Bridger Range I found unstable hard wind slabs on small wind-loaded terrain (<a href="https://www.mtavalanche.com/node/30082"><span…;). Even just a few inches of snow and moderate wind will make avalanches more likely today. A remarkably wide avalanche on Buck Ridge (<a href="https://www.youtube.com/watch/IoM5zbOF5E4"><s…;) last Thursday is another example of what you could trigger today. Choose terrain carefully, and evaluate the snowpack for fresh wind-loading and older hard wind-slabs sitting on weak, sugary snow. Avalanche danger is CONSIDERABLE on wind-loaded slopes and MODERATE on other slopes.

In the northern Gallatin Range large avalanches are possible to trigger. It has become less likely to trigger a large slide without as much recent loading from new snow and wind as other areas, but the potential consequences of an avalanche require careful route-finding and snowpack evaluation. On Thursday skiers triggered slides from 150 ft away in <a href="https://www.mtavalanche.com/node/30026"><…;, and on Friday a skier triggered an avalanche on a windloaded slope just below the ridgeline on the E face of Mt. Blackmore (<a href="https://www.mtavalanche.com/node/30064"><span…;). Yesterday, skiers reported a recent natural avalanche on the same slope (<a href="https://www.mtavalanche.com/node/30087"><span…;). These are examples of the dangerous avalanches that you can trigger today. Carefully assess the snowpack for unstable slabs and recent wind-loading, and seek non-wind-loaded terrain or avoid steep slopes altogether. The avalanche danger is MODERATE in Hyalite.

Read more about GNFAC Avalanche Forecast for Sun Jan 21, 2024

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Wet Loose in Beehive Basin

Date

Sat, 01/20/2024 - 14:15

Activity

Skiing

While skiing into Beehive Basin from the ridge between Beehive and Middle basin we noticed some sizable natural wet loose avalanches. West facing, around 9000 feet, 10-12 inches deep, ran ~150 feet, observed at 2:15 pm. The new snow from last weeks storm had warmed and slid on the weak snow below.

Region

Northern Madison

Location (from list)

Beehive Basin

Observer Name

Spencer L

Avalanches, collapsing, cracking in Cooke

Republic Creek

Cooke City

1/20/2024

Code

Latitude

44.98550

Longitude

-109.94100

Notes

Ski toured to west Woody Ridge today, south of Cooke City.

We set a new skin track and I would estimate that 80%+ of the snow we touched created a large collapse/ whompf. Many of the collapses were large and loud (over 100' wide). It seemed like remotely triggering an avalanche would have been easy/ likely had we been connected to steeper slopes.

We noted widespread avalanche activity in a nearby gully (NW aspects) adjacent ski tracks from yesterday.

In our snowpit at 9700', on a westerly aspect, we had an ECTPV. On 2mm facets, 45cms down.

I've skied that area a lot over the last 15 years, commonly during big snowstorms and elevated avalanche hazard, but today seemed like one of the most hazardous, if not THe most hazardous days for avalanches I experienced there- given the widespread nature of the PWL and thickness and sensitivity of the slab.

The warm temperatures today likely had a significant influence on the instabilities. (35 deg F in town for much of the afternoon.) Lots of roof-a-lanches noted today as well.

Number of slides

Number caught

Number buried