23-24

Weak Snow on Saddle Peak

Date
Activity
Skiing

Alex and I began to dip our toes into a Saddle Peak stability assessment. Given the new snow and HIGH danger on wind-loaded terrain in the Bridger Range, we decided early to skip the summit and cross onto the edge of the Football Field from the Bridger Bowl boundary. Upper slopes had fresh drifts of wind-loaded snow and new cornice growth, but there was not as much loading as we feared there might be. We stuck to our conservative plan and skied the "Bitter End" (the closest run to the south boundary of the ski area) down to 8400' elevation before ducking out across the boundary. 

The snowpack is thin and weak, with advanced facets making up most of it. Our test results did not reveal obvious instability, just weakness (ECTX). It is unreasonable to apply that same assessment across the Peak. Human-triggered avalanches are certainly possible, especially in areas with thicker slabs of wind-drifted snow (something that is quite common to find on Saddle Peak). Given the very high-consequence nature of the area, we advise patience and conservative terrain choices and decision-making. 

Region
Bridger Range
Location (from list)
Saddle Peak
Observer Name
David Zinn

Remote Trigger Near Hyalite Peak

Date
Activity
Skiing

We skinned up towards Hyalite peak today to see how the snowpack was adjusting to this new load. While we did see some point release on the canyon walls during our approach, there was no collapsing and minimal wind effect below 9000 feet. As soon as we topped out into the hyalite lake basin, a northerly wind picked up and there were supportable wind drifts scatted about. Got an ECTx on a northern aspect at 9200' before deciding to ascend a 25 degree adjacent slope. About 50' from our pit we remotely triggered two D1 slab avalanches which broke on the roll over 150' above us. Crowns looked between 1-2' and 20-30' wide. The larger of the two ran 100' more or less. Yikes, time to bail! The low angle tree skiing along the skinner was quite nice.

Region
Northern Gallatin
Location (from list)
Hyalite Peak
Observer Name
Sam Lowe

Pebble Creek

Date
Activity
Skiing

115-120 cm HS @ 8250'

Temp in the low 20's.  Overcast until at least 3 p.m. 

West side of tree trunks snowblasted by wind, both on the south and north sides of the ridge into Pebble Creek.  

Experienced whoomphing starting at 8000', midway up the gully, south side of the ridge, where there was some wind deposition.  Parallel cracks 10' apart - looked like "stretch" marks.  Extensive whoomphing in the saddle and down in Pebble Creek Valley.  Ski penetration = knee deep, and trail breaking was a bit of work today.  18" new snow at 8250' and in Pebble Creek.  Snow was too deep for turns on mellow slopes, and too much collapsing to go steeper.  Occasionally broke through the hard layer, into the hollow below.  

Still windy in Pebble Creek (less than 10 mph), but definitely wind scoured.  Looked like a natural avalanche on SE facing slope of the ridge to the N of Pebble Creek.  

Coverage still slim down towards the highway.  

Region
Out of Advisory Area
Location (from list)
Pebble Creek - YNP
Observer Name
Traute Parrie, D Carroll

Remotely Triggered Avalanche on Henderson Mountain, Cooke City

Henderson Mountain
Cooke City
Code
SS-ASr-R3-D2-O
Elevation
9500
Aspect
SW
Latitude
45.05240
Longitude
-109.94500
Notes

On the west side of Henderson Moutain, while ascending a low-angle slope toward a known avalanche path, we experienced several collapses. Halfway up the slope, Ian noted snowballs rolling down the hill and around the corner, we could see the debris that had come from the steep terrain above. We had a clear view of this slope near the snowmobiles and it had not avalanched when we began ascending. At some point from several hundred feet away, we remotely triggered the slope. The avalanche was ~150' wide, 2' deep and ran almost to the road. Across the gully, we could see large cracks but the slope did not avalanche. Above, cracking and collapsing continued and we got a view into the upper part of the gully and saw another crown of an avalanche that likely happened at the same time as the slope below. 

 

 

Number of slides
1
Number caught
0
Number buried
0
Avalanche Type
Soft slab avalanche
Trigger
Skier
Trigger Modifier
r-A remote avalanche released by the indicated trigger
R size
3
D size
2
Bed Surface
O - Old snow
Problem Type
Persistent Weak Layer
Slab Thickness
18.0 inches
Vertical Fall
350ft
Slab Width
150.00ft
Weak Layer Grain type
Near surface faceted particles
Weak Layer grain size
2.00mm
Weak Layer Hardness
F
Snow Observation Source
Slab Thickness units
inches
Single / Multiple / Red Flag
Single Avalanche
Advisory Year

Natural Avalanches north of Cooke City

Multiple locations
Cooke City
Code
SS-N
Aspect Range
E,W,S
Latitude
45.67910
Longitude
-111.04200
Notes

While riding north of Cooke City we noted many natural avalanches on east, west, and south-facing slopes at all elevations. Crowns ranged in depth from 1-2'. Most of these avalanches were not side very wide but several were including, Crown Butte, Henderson Mountain, and Miller Ridge. All of these avalanches happened near the end of yesterday's storm. 

 

Number caught
0
Number buried
0
Avalanche Type
Soft slab avalanche
Trigger
Natural trigger
Problem Type
Persistent Weak Layer
Slab Thickness
18.0 inches
Slab Thickness units
inches
Single / Multiple / Red Flag
Multiple Avalanches
Advisory Year

Small Rider Triggered Avalanche in Cooke City

Sheep Mountain
Cooke City
Code
AMr
Elevation
9600
Aspect
S
Latitude
45.07220
Longitude
-109.92800
Notes

A small avalanche was triggered from the flats 100' away by a rider as they were getting their snowmobile unstuck. 

Number of slides
1
Number caught
0
Number buried
0
Trigger
Snowmobile
Trigger Modifier
r-A remote avalanche released by the indicated trigger
Snow Observation Source
Slab Thickness units
centimeters
Single / Multiple / Red Flag
Single Avalanche
Advisory Year