24-25

On this first day of spring, Ian and I toured up the northern ridge above Hebgen Lake today looking for weak snow near the base of the snowpack. Throughout the day, it snowed a little over an inch with bursts of sunshine in and out.

From the storm over the weekend, we noted about 1.5" of new and settled snow. We saw no cracking or collapsing or any other signs of instability.

We dug a snowpit at 8900' on a NE aspect (HS: 163), and while we found faceted snow at the bottom of the snowpit, beneath the dirt layer, we were only able to get propagation on this layer after extra hits. We got a few ECTN's (7, 17) higher up in the snowpack.

While we were encouraged by how few signs of instability we saw today, we are not ready to discount the possibility that avalanches could break on these weak layers, especially after seeing the persistent weak layer avalanche yesterday in the Taylor Fork. As always, if choosing to travel in steep terrain, use safe travel practices: one at a time on steep slopes, carry rescue gear, and regroup in safe zones.

Region

Lionhead Range

Location (from list)

Hebgen Lake

Observer Name

H. Darby

Still Weak Layers, Hebgen Lake - 20 March 2025

Read more about Still Weak Layers, Hebgen Lake - 20 March 2025

Blowing and drifting snow mid elevation Island Park

Date

Thu, 03/20/2025 - 14:35

Activity

Snowmobiling

All elevations in Island Park experienced heavy snowfall combined with high winds,this made for unstable wind slabs and cornices.

Region

Island Park

Location (from list)

Two Top

Observer Name

Kevin Allred

Great skiing. Dry loose. No concerning ECT results

Date

Thu, 03/20/2025 - 11:05

Activity

Skiing

Dug a pit and did a ECT. Stayed off of wind-loaded slopes and found phenomenal skiing. On very steep pitches we found some dry loose activity.

We found 175cm of snow

ECTX4@ 168cm

ECTX24@105cm

35 degree slope. 7150 ft

North facing - 10 degrees

Region

Northern Gallatin

Location (from list)

Storm Castle

Observer Name

T. Goodman

Skier Caught and carried in Bridgers pinnacle’s

Date

Wed, 03/19/2025 - 11:30

Activity

Skiing

Skier caught and carried approx 100 yards thru pinch of main pinnacle chute. Skier was not buried but did lose ski. Suspected culprit of avalanche was cornice drop or skier above sliding down into us. We observed little to no movement or activity before dropping into line besides prior day cornice drop slides. Slide footage can be found @0:55 mark of linked video

https://www.instagram.com/reel/DHZhI6DMGse/?igsh=YWgxd3cyaGpzY3F5

Region

Bridger Range

Location (from list)

BRIDGER RANGE

Observer Name

Noah B

Small wind slab avalanches on Saddle Peak

Saddle Peak

Bridger Range

3/19/2025

Code

SS-N-R1-D1-I

Elevation

9000

Aspect

Latitude

45.79430

Longitude

-110.93600

Notes

It looked like there were several small wind slabs triggered on Saddle Peak. I was skiing with my family and didnt get a good look or a photo. One appeared to be just off the summit maybe 12" deep and not running very far at all. The other appeared to be near the going home chute even with the cliffs, and this one ran a bit further. These wind slabs looked like something to be looking for but also easy to avoid.

Number caught

Number buried

Avalanche Type

Soft slab avalanche

Trigger

Natural trigger

R size

D size

Bed Surface

I - Interface between new and old snow

Problem Type

Wind-Drifted Snow

Read more about Small wind slab avalanches on Saddle Peak

Slab Thickness

12.0 inches

Snow Observation Source

Wind slabs on Saddle

Slab Thickness units

inches

Single / Multiple / Red Flag

Multiple Avalanches

Advisory Year

24-25

Old Wind Slab Avalanche South of Cooke

COOKE CITY

Cooke City

3/14/2025

Code

SS-N-R2-D2-U

Elevation

9600

Aspect

Latitude

45.02020

Longitude

-109.93800

Notes

We were split boarding south of Cooke City today, up to terrain around 10'000', and finding good snow stability.

Weather was mostly cloudy in the am, partly cloudy in pm. Light winds from the SW.

No fresh avalanche activity observed. Attached is a photo of the only sign of a recent avalanche we could find. (an old crown on an East aspect at 9600').

Number of slides

Number caught

Number buried

Avalanche Type

Soft slab avalanche

Trigger

Natural trigger

R size

D size

Bed Surface

U - Unknown

Problem Type

Wind-Drifted Snow

Read more about Old Wind Slab Avalanche South of Cooke

Images

Old avalanche crown south of Cooke City. East aspect, 9600'.

Snow Observation Source

Cooke City, finding good stability

Slab Thickness units

centimeters

Single / Multiple / Red Flag

Single Avalanche

Advisory Year

24-25

GNFAC Avalanche Forecast for Thu Mar 20, 2025

Snowpack and Avalanche Discussion

Snow totals from the weekend storm range from 24-46 inches of snow containing 2.3-4.8 inches of water. Many slopes have a deep, <a href="https://www.mtavalanche.com/node/34679"><… snowpack and good stability</a>, BUT not all. There are two main avalanche problems, one is easy to avoid while the other is more tricky.

Heavy snowfall and ferocious winds formed large wind slabs last weekend and early this week. While these wind slabs may have stabilized some the last two days, more wind and snow will load the same slopes today keeping them on edge. These wind slabs can be quite large and mostly an issue at upper elevations above treeline. Several great examples of this problem were avalanches spotted yesterday north of Cooke City <a href="https://www.mtavalanche.com/node/34685"><… Wolverine Peak and Scotch Bonnet</a> and <a href="https://www.mtavalanche.com/node/34690"><… Goose Lake</a>.

The load of such heavy snowfall has also awakened a persistent slab avalanche problem, but this one is really tricky. Slopes with a relatively thinner snowpack still harbor weak, faceted snow and can produce avalanches like <a href="https://www.mtavalanche.com/node/34684"><… in Sunlight Basin</a> in the southern Madison Range yesterday. Some areas may have a thinner snowpack overall and will be easy to identify by digging a snowpit. Other areas will have isolated slopes with a thinner snowpack because they either previously avalanched or were scoured by winds at another time.

Today wind loaded slopes (loaded last weekend and being loaded again today) have a CONSIDERABLE avalanche danger. Slopes not loaded by winds have a MODERATE danger, but this is tricky. Riding slopes less than 30 degrees in steepness that aren’t steep enough to slide is always a great option.

The mountains near Bozeman and Big Sky have a strong deep snowpack, and the single avalanche problem is wind slab avalanches. Ski patrols triggered wind slabs 6-12 inches deep yesterday. While skiing at Bridger Bowl yesterday, I thought I could see several small wind <a href="https://www.mtavalanche.com/node/34696"><… triggered on Saddle Peak</a>, one at the top and one maybe halfway down.

Winds increased again this morning from the W and SW. They should be moving more snow today, building new wind slabs and keeping older ones on edge. As Ian found <a href="https://www.mtavalanche.com/node/34666"><… the Throne in the Bridgers on Tuesday</a>, the simplest option for good skiing and riding as well as good stability is to ride slopes sheltered from the wind.

Today with a little bit of snow falling and strong winds blowing, the avalanche danger will be CONSIDERABLE on wind loaded slopes. Getting out of the wind will be a challenge, but slopes sheltered from the wind with no wind deposited snow will have good stability and a LOW danger.

Read more about GNFAC Avalanche Forecast for Thu Mar 20, 2025

Subscribe to 24-25