23-24

Cornice Collapse on the Sphinx

Sphinx Mountain
Southern Madison
Code
C-ASu
Latitude
45.15820
Longitude
-111.47700
Notes

From obs: " Unintentionally triggered a large cornice collapse on the south face of the Sphinx. " 

Number of slides
1
Number caught
0
Number buried
0
Avalanche Type
Cornice fall
Trigger
Skier
Trigger Modifier
u-An unintentional release
Snow Observation Source
Slab Thickness units
centimeters
Single / Multiple / Red Flag
Single Avalanche
Advisory Year

Natural Wet Snow Avalanches Crazy Mtns.

Crazy Peak
Out of Advisory Area
Code
WL-N-R2-D2
Aspect Range
E-S
Latitude
46.01870
Longitude
-110.27600
Notes

Riders saw several natural wet snow avalanches while riding on the west side of the Crazy Mountains. The largest of these was 500' wide, D2. All these avalanches happened in the upper 40cm of the snowpack. 

Number caught
0
Number buried
0
Avalanche Type
Wet loose-snow avalanche
Trigger
Natural trigger
R size
2
D size
2
Problem Type
Wet Snow
Snow Observation Source
Slab Thickness units
centimeters
Single / Multiple / Red Flag
Multiple Avalanches
Advisory Year

good stability on N aspects at 9000 ft in N. Gallatins

Date
Activity
Skiing

We skied two North-facing lines in the Northern Gallatin range on Wednesday ranging in elevation from 8500 - 9700 ft with some slight West and East flavor. We saw no signs of instability and set off a couple large sluffs in the top 8-12" of snow and some wind-loaded pockets breaking 6-8" deep. I dug a pit and did a CT and ECT and got CT15 on new snow 30cm deep and CT28 on a layer 45 cm deep. Got ECTN16 on same 30-35 cm deep new snow layer. The interface with the old freeze-thaw layer below the new snow did not show a very high quality fracture plane / bed surface for the upper new snow to slide on. the freeze-thaw layer was about 1-2cm thick but did not feel it while skiing. Upon pulling on ECT column with shovel, broke on 45-cm layer with poor quality and also on basal facet layer at ground. Overall right-side-up snowpack density going from fist to pencil hardness pretty linearly. Total depth of snow 210cm. Depth of new snow from last storm approx. 12-16". 9600 ft NNE aspect. 

Region
Northern Gallatin
Location (from list)
Alex Lowe Peak

Cornice Collapse on the Sphinx

Date
Activity
Skiing

Unintentionally triggered a large cornice collapse on the south face of the Sphinx.  I should have expected it, but it was certainly touchier than I was anticipating. Intermittent wind gusts kept upper elevations cooler and we found somewhat cold snow up high. At treeline and below it was hot and crusty! Photos show cornice before and after. 

Region
Southern Madison
Location (from list)
Sphinx Mountain
Observer Name
Haylee Darby

Crazy mtns

Date
Activity
Snowboarding
Snowmobiling

Rode up cottonwood creek on the west side of the crazies. Saw several recent wet loose slides on southern aspects as well as some isolated slides on north/west aspects. Only saw one larger slide that had a wide crown(500ft) D2 on an east aspect.  All slides were breaking in the upper 40cm in new/old snow.

 

Dug a pit north east aspect HS270cm ECTN24 @40cm down from surface. Melt freeze down 70cm might start reacting when water penetrates through upper snow pack, dry snow in upper 60cm but becoming more moist on solars.

Region
Out of Advisory Area

Good test scores on Henderson

Date
Activity
Snowboarding

Dug a pit on our way up the west side of Henderson Mountain. Incline 26 degrees, elevation 9545. Surface depth at 165cm, dug down to about 65cm. Performed extended column test and yielded ECTN17 along melt freeze crust at 135cm above ground. 

Region
Cooke City
Location (from list)
Henderson Mountain
Observer Name
Greg Krumel

Wet Loose Avalanches in Argentina Bowl

Argentina Bowl
Bridger Range
Code
N-R2-D2
Elevation
9000
Aspect
E
Latitude
45.78690
Longitude
-110.93500
Notes

Driving home from Bridger Bowl I spotted a number of wet loose avalanches in Argentina bowl. It was 1:30 PM when I saw them and the sun was still blazing. I would expect there was more activity as the afternoon progressed.

Number caught
0
Number buried
0
Trigger
Natural trigger
R size
2
D size
2
Problem Type
Wet Snow
Snow Observation Source
Slab Thickness units
centimeters
Single / Multiple / Red Flag
Multiple Avalanches
Advisory Year