24-25

Natural storm slabs northern Bridgers

The Throne
Bridger Range
Code
R2-D2-S
Elevation
8500
Aspect
E
Latitude
45.88220
Longitude
-110.95200
Notes

From IG: 3 separate natural slides viewed south of the throne today. All east facing. This was the biggest. 
If this is R3 others were more R2

Number of slides
3
Number caught
0
Number buried
0
R size
2
D size
2
Bed Surface
S - Avalanche released within new snow
Problem Type
Storm Slab
Snow Observation Source
Slab Thickness units
centimeters
Single / Multiple / Red Flag
Multiple Avalanches
Advisory Year

Small Wind Slab Avalanche On Middle Peak

Date
Activity
Skiing

Cohesive wind slabs roughly 1 foot deep were triggered between middle peak and the going home chute on the northeast aspect. Upon skiers weight shooting cracks traveled roughly 100 feet to trigger a small avalanche. The size was small as only the top 50 feet of the slope slid but the snow from the avalanche carried down the entire face.

Region
Northern Madison
Location (from list)
Middle Basin

Natural wind slabs on Peets Hill

Date

On the summit of Peets Hill we saw a fresh natural wind slab avalanche, around 1130 this morning. West aspect, 5055’ elevation. Relatively harmless to a cat or small dog C1, R2. We also saw similar slides on a slope lower on the hill. Photos attached.

Cold east winds were forming drifts on top of old drifts from previous east wind events. In some spots these old drifts have made the slope steeper than the usual slope of the ground below, essentially creating new/temporary avalanche start zones. The avalanche potential size is currently small, but with the right amount of snow, and probably east wind, there is potential for avalanches that could be large enough to bury or injure a cat (C2) or even a large dog (C3). 

In some places my paws punched through into weak sugary snow below, so with big storm or loading event there might be potential for a persistent slab that could hurt a human in a few areas where slopes are steeper than 30 degrees. 

HS was shoulder deep on a small border collie where not drifted. There were some old ski tracks as well which looked like more fun to trench through than just walking on the trail.

Location (from list)
Other place
Observer Name
Coco-Nut

Natural storm slabs northern Bridgers

Date

From IG: 3 separate natural slides viewed south of the throne today. All east facing. This was the biggest. 
If this is R3 others were more R2

Region
Bridger Range
Location (from list)
The Throne
Observer Name
Isaac Freeland

Wind Slab and Storm Slab on S.Face of Ellis

Date
Activity
Skiing

At 16:10 I arrive at the sumit of Ellis. The wind was Westerly 0-5mph. I planned to ski the South Face of Ellis and then come up and ski the typical East face slides back to the car. The south face was skied on Saturday and I was told there was a stout melt freeze crust with roughly 6 inches of new snow. I was also told it was skied out after 4 skier had skied the face.
 

From the summit I make 2 ski cuts to safe spots. The snow was unreactive, but it was wetter/ denser than expected. There was 6-8 inches of new snow. Roughly 150-200 vertical feet down the face I bailed. Wind affected snow was becoming widespread and I noticed the new snow falling at the apex of my turns (storm slabs). The new snow was thinner, 4-6 inches and the crust was very noticeable. In tight trees I transitioned and skinned over to east face. Skiing through newly formed wind slabs there were small shooting cracks (not particularly energetic) that extended roughly 10 feet. Wind slabs were up to 2 feet deep. The melt freeze crust was easily breakable in some places and unbreakable in others. 
 

Long winded, but the new snow and wind loading  lined up exactly with the forecast. 

Region
Northern Gallatin

Intentionally Triggered Avalanche on Ramp

The Ramp
Bridger Range
Code
SS-ASc-S
Latitude
45.82880
Longitude
-110.93100
Notes

While skiing a SE-facing slope, we found cracking and some cohesion in the new snow. This was mostly on very steep and rocky terrain features. The most notable of these was about 20’ wide, the bottom part of the new slab only moved about 6” before stopping, while the upper foot of the slab ran the full face. 

Number of slides
1
Number caught
0
Number buried
0
Avalanche Type
Soft slab avalanche
Trigger
Skier
Trigger Modifier
c-A controlled or intentional release by the indicated trigger
Bed Surface
S - Avalanche released within new snow
Problem Type
Storm Slab
Slab Thickness
12.0 inches
Slab Width
20.00ft
Snow Observation Source
Slab Thickness units
inches
Single / Multiple / Red Flag
Single Avalanche
Advisory Year

Storm snow instabilities

The Ramp
Bridger Range
Code
SS-N-R2-D2-S
Latitude
45.82880
Longitude
-110.93100
Notes

Most steep chutes we skinned near had a debris pile at the bottom (running full path). 

Number caught
0
Number buried
0
Avalanche Type
Soft slab avalanche
Trigger
Natural trigger
R size
2
D size
2
Bed Surface
S - Avalanche released within new snow
Problem Type
Storm Slab
Snow Observation Source
Slab Thickness units
centimeters
Single / Multiple / Red Flag
Multiple Avalanches
Advisory Year