19-20

Skier triggered small wind slabs in Beehive

Beehive Basin
Northern Madison
Code
SS-ASc-R1-D1.5-S
Elevation
9500
Aspect Range
NE-E-SE
Latitude
45.34070
Longitude
-111.39100
Notes

From e-mail: "Skied in the the beehive area today. Triggered some small wind slabs that were sliding on a crust. 

E aspect 9,100': Triggered from a stomping a small cornice, which landed on a steep slope below and popped a small wind slab.

NE aspect 10,000': Triggered while skiing through a choke point. This one was thin but ran down slope quite a ways because the terrain was steeper. It was easy to avoid by skiing off to the right, since the gully was just cross loaded a bit on the left.

SE aspect 9,800': The third was just some propagating cracks. The slope angle wasn't quite steep enough to slide here.

These instabilities appeared to be confined to areas of dense wind drifted snow on top of a crust layer and did not appear to be wide spread."

Number of slides
2
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
R size
1
D size
1.5
Bed Surface
S - Avalanche released within new snow
Problem Type
Wind-Drifted Snow
Slab Thickness units
centimeters
Single / Multiple / Red Flag
Multiple Avalanches
Advisory Year

Collapsing of a wind slab in Hyalite

Hyalite - main fork
Northern Gallatin
Code
Aspect
W
Latitude
45.44720
Longitude
-110.96200
Notes

"I postholed up to Zach Attack today and dug a pit in the gully a few hundred feet below the route. We found about a meter of snow on the ground, the upper 65 cm being generally unconsolidated (fist-4F hardness) snow largely transported by the wind. Below that was a 5-10 cm MFcr on top of small (1-2 mm) basal facets. Higher up in the gully we found a few isolated winds slabs, and on the way my back down one of my partners felt a wumph as we crossed above a leeward convexity."

Number of slides
0
Number caught
0
Number buried
0
Slab Thickness units
centimeters
Single / Multiple / Red Flag
Red Flag
Advisory Year

Natural wind slabs and dry loose avalanches Mt. Blackmore

Mt Blackmore
Northern Gallatin
Code
SS-N-R1-D1-S
Elevation
9500
Aspect Range
E-NE
Latitude
45.44440
Longitude
-111.00400
Notes

From obs., "Activity I observed was restricted to the new snow. A fair bit of loose snow....  Skiers on the E bowl of Blackmore triggered some D1 dry sluffage, running on a crust beneath the new snow.... No slab activity observed until the wind started pushing more snow around this afternoon. I watched a small (D1) wind slab build and fail as the wind picked up near the Blackmore/Elephant saddle (happened just before 2pm). Slab couldn't have been much thicker than 15cm, broke 30-40m wide. These slabs were building rapidly..."

Number caught
0
Number buried
0
Avalanche Type
Soft slab avalanche
Trigger
Natural trigger
R size
1
D size
1
Bed Surface
S - Avalanche released within new snow
Problem Type
New Snow
Slab Thickness
6.0 inches
Slab Width
100.00ft
Slab Thickness units
inches
Single / Multiple / Red Flag
Multiple Avalanches
Advisory Year