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skier triggered large slide near Daisy

Daisy Pass

Cooke City

3/2/2023

Code

HS-ASc-R3-D2.5-O

Elevation

10000

Aspect

Latitude

45.05280

Longitude

-109.95000

Notes

From IG message 3/3/23: "Yesterday on March 2nd we were on the trail to daisy pass just before the bowl in cooke city. There were 12 of us of us no total. Just behind us a large avalanche came down covering the trail and clearing trees on the way. We went to investigate to make sure there were no burials when 2 skiers came down and said they were stomping on the facet layer and triggered it intentionally. The slide swept the skier’s parked snowmobile off trail and carried it about 100 feet."

From email 3/3/23: "We rode over [Daisy Pass] in the afternoon around 5pm and it hadn't been there when we went over the pass early that morning. We heard from a couple of other snowmobilers that some folks had been skiing up there, parked a sled at the bottom for their lap, then triggered the slide by ski cut before they dropped in. The slide buried their sled and they had to dig it out. Here's a few photos that I took that afternoon."

From email 3/3/23: "... Crown looks 5-6' deep, 150'+ wide and SW aspect. Here is a picture."

Number of slides

Number caught

Number buried

Avalanche Type

Hard slab avalanche

Trigger

Skier

Trigger Modifier

c-A controlled or intentional release by the indicated trigger

R size

D size

2.5

Bed Surface

O - Old snow

Problem Type

Persistent Weak Layer

Read more about skier triggered large slide near Daisy

Slab Thickness

48.0 inches

Vertical Fall

500ft

Slab Width

200.00ft

Weak Layer Grain type

Surface Hoar

Weak Layer grain size

3.00mm

Slab Layer Hardness

Images

Daisy Pass Snowpit Profile

Skier triggered avalanche near Daisy Pass, crown and debris

Skier triggered avalanche near Daisy Pass 4

Skier triggered avalanche near Daisy Pass 3

Skier triggered avalanche near Daisy Pass 2

Skier triggered avalanche near Daisy Pass

Skier triggered avalanche across road near Daisy Pass

Attached Videos

Deep Slab Avalanches in Cooke - 3 March

Snow Observation Source

skier triggered slide near Daisy

Slab Thickness units

inches

Single / Multiple / Red Flag

Single Avalanche

Advisory Year

22-23

Read more about Skier triggered avalanche across road near Daisy Pass

From email 3/3/23: "Another natural avalanche that ran across the road near Daisy pass last night. Our groomer took this picture. I was also informed that some skiers triggered an avalanche near Daisy yesterday afternoon. No other details on that. This would be a w/SW facing slope." Photo: UYSC Groomer

Avalanche Details: skier triggered large slide near Daisy
Forecast link: GNFAC Avalanche Forecast for Fri Mar 3, 2023

Cooke City, 2023-03-03

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skier triggered slide near Daisy

Date

Thu, 03/02/2023 - 03:55

After further investigation: "It is the same avalanche that the skiers triggered. Crown looks 5-6' deep, 150'+ wide and SW aspect."

Region

Cooke City

Location (from list)

Daisy Pass

Observer Name

Ben Zavora

GNFAC Avalanche Forecast for Fri Mar 3, 2023

Snowpack and Avalanche Discussion

The mountains south of Big Sky to West Yellowstone and Cooke City harbor weak layers which are a concern. Yesterday's 1-3” of snow and southwest wind are not helping the stability. It has snowed 11 of the last 12 days and the snowpack has not gotten a restful break. Incremental loading is on our mind (<a href="https://www.mtavalanche.com/weather/wx-avalanche-log"><span… and Avalanche Log</a>) as are recent signs of instability. <a href="https://www.mtavalanche.com/node/28386"><span… City had many large avalanches</a> break into Tuesday. Dave looked at a <a href="https://youtu.be/K9abJNvfWOs">… slide in Taylor Fork</a>, I found <a href="https://www.youtube.com/watch?v=tyvsM8r40S4">… snow at Lionhead</a>, skiers had a <a href="https://www.mtavalanche.com/node/28384"><span… at Quake Lake</a> and <a href="https://www.mtavalanche.com/node/28397"><span… pit scores at Bacon Rind</a>. Although avalanches are not imminent, they could still be triggered by a sledder or skier. We have useful links to <a href="https://www.mtavalanche.com/snow-observations-list"><…, photos and observations </a>that give color and depth to the recent slides and red flag activity.

Wind and snow can be a dangerous combination.  We need to be careful to not trigger slides on wind-drifted slopes. Stay clear of these thicker, smooth slabs of drifted snow, dig and test the layers under your feet and be wary on steep slopes, wind-loaded or not.

The avalanche danger is rated MODERATE.

The mountains around Bozeman and Big Sky have been windy with 6-12” of new snow since Sunday. Wind has blown the new snow into drifts, with each day's snowfall creating a new, dense layer in the snowpack. Overall these layers are bonding well, but last night's wind coupled with loose snow (<a href="https://www.mtavalanche.com/images/23/mt-blackmore-snowpit-profile"><sp…” at Mt. Blackmore yesterday</a>) will keep our avalanche eyeballs wide open. Shooting cracks in wind drifts are a red flag of instability. Yesterday, in my snowpit video in Hyalite, I mentioned staying off of wind-loaded slopes, advice that applies today. Last Friday and Monday there were large slides in Hyalite on the east face of <a href="https://www.mtavalanche.com/node/28286"><span…. Blackmore</a> and <a href="https://www.mtavalanche.com/node/28358"><span…. Bole</a>, which indicates deeper instabilities on a few, isolated slopes.

Given the possibility of avalanches and the need to investigate the snowpack for instabilities, the danger is rated MODERATE.

Please share avalanche, snowpack or weather observations via our<a href="https://www.mtavalanche.com/node/add/snow_obs">…; website</a>, email (mtavalanche@gmail.com), phone (406-587-6984), or Instagram (#gnfacobs).

The mountains have gotten snow 11 of the last 12 days totaling almost 25”. Buried weak layers which are a concern. We also need to be careful to not trigger slides on wind-drifted slopes. Stay clear of these thicker, smooth slabs of drifted snow, dig and test the layers under your feet and be wary on steep slopes, wind-loaded or not.

Read more about GNFAC Avalanche Forecast for Fri Mar 3, 2023

Upcoming Avalanche Education and Events

Our education calendar is full of awareness lectures and field courses. Check it out: Events and Education Calendar.

Weather and Avalanche Log for Fri Mar 3, 2023

Read more about Weather and Avalanche Log for Fri Mar 3, 2023

South Fork Deep Creek- Town Hill

Date

Thu, 03/02/2023 - 11:45

Activity

Skiing

Hi,

My partner and I toured up the south fork of deep creek and skied the lawnmower on town hill. Conditions were variable, we found good snow in the upper portion of the lawnmower but the mid to low elevations were extremely scoured and/or icy. Snow along ridgelines had been drifted into thick, very hard slabs. We dug a pit at 9000', NW aspect. HS170, ECTPX. The snowpack above the weak, sugary facets near the ground seemed generally right side up and stable. No cracking or collapsing except for a thin layer of what looked like near surface facets or surface hoar in the top two inches. We kicked off many small, inch to half-inch thick wind slabs on our way down, that only propagated a few feet out while skiing down. We weren't concerned given this weak snow was confined to the very top of the snowpack, but it could be an issue in the future. Near the bottom of the slide path we saw one small wind slab avalanche that was likely skier triggered, but that was the only avalanche activity we observed. Hopefully this info is useful.

Region

Out of Advisory Area

Observer Name

Nicholas Salsburg

Read more about Mt. Blackmore Snowpit Profile

Northern Gallatin, 2023-03-02

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Layers of Wind Slabs

Date

Thu, 03/02/2023 - 11:30

Activity

Skiing

We skied to the east face in mostly calm conditions. Last night's 2" of new snow was not blown around. We could still see the crown of the natural avalanche that broke on Friday, 24 February. Skiing across wind drifts produced no cracking. We dug off the ridge on the east face near the first line down. HS was 215 and we got an ECTN 11 at 195 cm. With a load of new or windblown snow this layer could propagate, but not today. The snowpack consisted of multiple layers of wind slab which was not surprising given the location.

Region

Northern Gallatin

Location (from list)

Mt Blackmore

Observer Name

Doug Chabot

Layers of Wind Slab, Hyalite - 2 March

Read more about Layers of Wind Slab, Hyalite - 2 March

GNFAC Avalanche Forecast for Thu Mar 2, 2023

Snowpack and Avalanche Discussion

I’m beginning to lose sleep over Cooke City. Alex saw a large avalanche on Henderson Bench yesterday that was released the night before, possibly from wind-loading (<a href="http://www.mtavalanche.com/node/28386">… and photo</a>). Another slide on Miller Ridge might have similar timing (<a href="http://www.mtavalanche.com/node/28400">…;). These mountains had snow on 10 of the last 11 days along with strong wind. On Saturday and Sunday, 4 people were caught and partially buried in 3 separate slides (<a href="https://www.mtavalanche.com/node/28338"><span… Hill</a>, <a href="https://www.mtavalanche.com/node/28331"><span…. Abundance</a>, <a href="https://www.mtavalanche.com/images/23/skier-triggered-slide-near-round-… Lake</a>). Large, recent avalanches are sprinkled over the range. The wind has died down and the chances of triggering slides has lessened, but is not gone. Tread gently in avalanche terrain, especially on slopes which are wind-loaded. These might not be obvious given the few inches of fresh snow covering layers of wind slab.

The avalanche danger is rated a serious MODERATE.

The mountains south of Big Sky to Lionhead have also gotten snow 10 of the last 11 days. Dave was in Taylor Fork yesterday and found an avalanche in Sage Basin that was triggered by a cornice fall (<a href="https://youtu.be/K9abJNvfWOs">…;). It broke 150 feet wide and 3 feet deep on a weak layer of surface hoar that was buried January 10th, which puts the word “persistent” into the term persistent weak layer. Yesterday, skiers on Bacon Rind had poor stability test scores on a layer of weak facets almost 2 feet deep (<a href="http://www.mtavalanche.com/node/28397">…;), and I found a weak interface at the same depth at Lionhead on Tuesday (<a href="https://www.youtube.com/watch?v=tyvsM8r40S4">…;). With weak layers being found and avalanches breaking early in the week, it is entirely possible to trigger an avalanche today. As Dave advises in his video, be especially wary around wind-loaded terrain and dig, test and only put one person at a time on a slope.

The avalanche danger is rated MODERATE.

The northern mountains around Big Sky and Bozeman had avalanche activity on Friday and Saturday from a large snowstorm, but the mountains have been quiet since then (<a href="http://www.mtavalanche.com/weather/wx-avalanche-log">… and Avalanche Log</a>). Last night's wind will blow snow into drifts which are our primary avalanche concern. Instabilities will be found near the ridgeline. We are not consistently finding buried weak layers which is a good sign, however, it remains prudent to dig and check the upper three feet of the snowpack just to be sure. Coming across a recent avalanche, no matter how small, is a sign of instability.

For today, the avalanche danger is rated MODERATE.

Please share avalanche, snowpack or weather observations via our<a href="https://www.mtavalanche.com/node/add/snow_obs">…; website</a>, email (mtavalanche@gmail.com), phone (406-587-6984), or Instagram (#gnfacobs).

The mountains have gotten snow 10 of the last 11 days totaling almost 20”. With weak layers being found and avalanches breaking early in the week, it is entirely possible to trigger an avalanche today. Be especially wary around wind-loaded terrain and dig, test and only put one person at a time on a slope. Triggering avalanches, especially in wind loaded slopes, is expected today.

Read more about GNFAC Avalanche Forecast for Thu Mar 2, 2023

Upcoming Avalanche Education and Events

Our education calendar is full of awareness lectures and field courses. Check it out: Events and Education Calendar.

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