22-23

Storm obs near Big Sky

Date

Sun, 03/26/2023 - 16:40

Activity

Skiing

Near Big Sky today we found 8-14" of right side up storm snow from 7500' to 9400' on a south southeast aspect. We observed very minimal and isolated cracking on the occasional wind pillow, but by and large the snow was non-reactive, unconsolidated, and very well bonded to the stout crust below.

Winds were light and variable and it snowed lightly all day, accumulating about 3" by the late afternoon.

Region

Northern Madison

Observer Name

Josh Lipkowitz

Wet slide in Lower Middle Cottonwood Canyon

BRIDGER RANGE

Bridger Range

3/19/2023

Code

WS-N-R3-D2-O

Elevation

5900

Aspect

Latitude

45.85120

Longitude

-110.94800

Notes

I observed the results of a wet slide avalanche within the first mile of Middle Cottonwood Creek Trail. The slide came down from the south side of the canyon (north facing), and crossed the trail at about 4-5' deep and 10' across at the trail with debris and into the creek at the creek crossing about .75 mile from the trailhead. The crown was only about 100' up the side of the canyon. The avalanche would've occurred earlier in the week, there was just the skiff of snow on it from the previous light snow (22nd?). In the rest of that section there are pinwheels all along that south canyon slope (north facing).

This is the 3rd wet slide I've seen in the last 3-4 weeks on Middle Cottonwood in the same region where the trail is on the south side of the creek (mile .4-.80 from summer trailhead). This area is easily accessible by hikers (I was running) and I've seen wet slides in that area 3 of the last 4 years once the sun hammers that south slope in the afternoon. I would expect more at the next warm spell after this current storm cycle.

Number of slides

Number caught

Number buried

Avalanche Type

Wet slab avalanche

Trigger

Natural trigger

R size

D size

Bed Surface

O - Old snow

Problem Type

Wet Snow

Read more about Wet slide in Lower Middle Cottonwood Canyon

Slab Thickness

12.0 inches

Vertical Fall

100ft

Slab Width

35.00ft

Images

Wet slide in Middle Cottonwood

Slide crossing trail at creek crossing, Middle Cottonwood

Snow Observation Source

Wet slide in Lower Middle Cottonwood Canyon

Slab Thickness units

inches

Single / Multiple / Red Flag

Single Avalanche

Advisory Year

22-23

Small skier triggered slide near Little Ellis, partial buried

Mt Ellis

Northern Gallatin

3/25/2023

Code

SS-AS-R3-D2-I

Elevation

7500

Aspect

Latitude

45.59710

Longitude

-110.96100

Notes

Came across debris of a recent skier-triggered slide near the top of Little Ellis in a small, protected, eastern facing gully around 7,500'. Crown was ~3.5-1.5' deep, ~35' wide and it ran ~150'. Ski tracks were observed near the top of the crown and next to a small hole near the surface ~70' from the crown where it looks like someone self extracted. No signal was found with a beacon search and my group felt that the one track from the hole must have been from the same skier as the track near the crown.

There was around 2-3' of heavy new snow at that location.

Number of slides

Number caught

Number buried

Avalanche Type

Soft slab avalanche

Trigger

Skier

R size

D size

Bed Surface

I - Interface between new and old snow

Problem Type

New Snow

Read more about Small skier triggered slide near Little Ellis, partial buried

Slab Thickness

30.0 inches

Vertical Fall

150ft

Slab Width

35.00ft

Images

Crown and hole of skier triggered avy, Little Ellis 2

Crown and hole of skier triggered avy, Little Ellis

Snow Observation Source

Small slide near Little Ellis

Slab Thickness units

inches

Single / Multiple / Red Flag

Single Avalanche

Advisory Year

22-23

Read more about Crown and hole of skier triggered avy, Little Ellis 2

[On 3/25/23]: Skier reported, "Came across debris of a recent skier-triggered slide near the top of Little Ellis in a small, protected, eastern facing gully around 7,500'. Crown was ~3.5-1.5' deep, ~35' wide and it ran ~150'. Ski tracks were observed near the top of the crown and next to a small hole near the surface ~70' from the crown where it looks like someone self extracted. No signal was found with a beacon search and my group felt that the one track from the hole must have been from the same skier as the track near the crown." Photo: R. Beck

Avalanche Details: Small skier triggered slide near Little Ellis, partial buried

Northern Gallatin, 2023-03-26

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Read more about Crown and hole of skier triggered avy, Little Ellis

Avalanche Details: Small skier triggered slide near Little Ellis, partial buried
Forecast link: GNFAC Avalanche Forecast for Mon Mar 27, 2023

Northern Gallatin, 2023-03-26

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Terrain, Terrain, Terrain - 26 March 2023

Read more about Terrain, Terrain, Terrain - 26 March 2023

Small slide near Little Ellis

Date

Sat, 03/25/2023 - 18:00

Activity

Skiing

There was around 2-3' of heavy new snow at that location.

Region

Northern Gallatin

Location (from list)

Mt Ellis

Observer Name

Reid Beck

GNFAC Avalanche Forecast for Sun Mar 26, 2023

Snowpack and Avalanche Discussion

Dangerous avalanche conditions exist and human-triggered avalanches are likely in the mountains near Bozeman, Big Sky and West Yellowstone. Since Friday night these mountains received 8-20” of new snow equal to 0.6-1.5” snow water equivalent (SWE). New snow amounts have been highly variable, and we received reports of 2-4 feet of low density snow in parts of Hyalite and the Bridger Range. Today a person can trigger large avalanches that involve the new snow. Avalanches will be larger and more likely where more snow fell, especially on slopes that have a hard crust below the new snow or where snow was drifted into thicker slabs. Yesterday, skiers in Beehive Basin saw a natural avalanche that was more than a foot deep and 75’ wide which shows what is possible today (<a href="https://www.mtavalanche.com/node/28817"><span…;). More snow through today will make natural avalanches possible and increase the potential size of human-triggered avalanches.

Additionally, there is a possibility avalanches could break several feet deep on old buried weak layers which would create a massive, likely unsurvivable avalanche (<a href="https://www.youtube.com/watch?v=xMbg_YQfgmw&list=PLXu5151nmAvTi1DBS…; from Mt. Blackmore). A slide that broke 8-10 ft deep earlier this week on Elephant Mtn. is the latest example of huge avalanches that could be triggered or break naturally today (<a href="https://www.mtavalanche.com/node/28785"><span… and photos</a>). See our <a href="https://www.mtavalanche.com/avalanche-activity"><stro… activity list</a> and <a href="https://www.youtube.com/playlist?list=PLXu5151nmAvTi1DBS5B4DBCruL1ULhkt… videos</a> for more examples of recent big slides. A good reason to choose objectives that avoid avalanche terrain.

Plan to avoid slopes steeper than 30 degrees altogether, or very carefully assess the stability of new and wind-drifted snow and potential for deep buried weak layers before traveling across or below steep slopes. Conservative decision making and cautious route finding are essential today. Human-triggered large avalanches are likely and avalanche danger is CONSIDERABLE.

In the mountains near Cooke City the main avalanche concern is a person triggering avalanches that break several feet deep on weak layers buried two months ago. On Thursday near Daisy Pass a snowmobiler triggered avalanche broke 4 feet deep, caught two riders, and one of them suffered a broken femur (<a href="https://www.mtavalanche.com/node/28785"><span… and photos</a>, <a href="https://www.facebook.com/100004284780258/videos/1424658804963632?idorva…;). Additionally, 3-5” inches of new snow from the last couple days will be drifted into thicker slabs that a person can trigger. If you plan to travel on or below steep slopes, choose smaller slopes that have not been recently wind-loaded and without large consequences such as trees, gullies or cliffs below. Human-triggered avalanches are possible and the avalanche danger is MODERATE.

Please share avalanche, snowpack or weather observations via our website, email (mtavalanche@gmail.com), phone (406-587-6984), or Instagram (#gnfacobs).

Dangerous avalanche conditions exist and human-triggered avalanches are likely. Today a person can trigger large avalanches that involve the new snow. Additionally, there is a possibility avalanches could break several feet deep on old buried weak layers which would create a massive, likely unsurvivable avalanche. Conservative decision making and cautious route finding are essential today.