Sawtooth Avalanche Center

Avalanche Occurrence

View Associated Field Report

General Information

This avalanche was remotely triggered from the ridgeline above. It failed on weak snow near the ground in an area with a thin, wind-affected snow pack.

Observer:
SAC Forecaster

Verified by SAC?
Yes

Occurrence Date:
Nov 23, 2022 5:00 pm (Exact)

Location:
near Grays Peak

Comments:

I remotely triggered 3 slides from the ridgeline. All 3 appeared to have failed on very well-developed facets (2-4mm xtals of depth hoar with striated cups). The layer of DH was 2-5cm thick and sat on a stout melt-freeze crust that was glued to the ground. A very stiff, dense slab sat on top of this weak snow. The slabs that failed were localized to near the ridgeline and tapered to nothing within about 30m of the ridge. The bed surface of the larger slide had lots of grass and sagebrush poking through it.

Avalanche Characteristics

# of Avys:
3
Aspect:
E (NE,E,SE)
Start Zone Elev:
9000ft
Size:
D1.5 / R1
Type:
HS-Hard Slab
Trigger:
AS-Skier
r-Remote
Bed Surface:
O-Old Snow
Depth:
1.5ft (max: 3ft)
Width:
100ft
Comments:

I did not have much time to investigate these slides due to the oncoming darkness, so these observations were collected quickly.

I remotely triggered 3 slides from the ridgeline. All 3 appeared to have failed on very well-developed facets (2-4mm xtals of depth hoar with striated cups). The layer of DH was 2-5cm thick and sat on a stout melt-freeze crust that was glued to the ground. A very stiff, dense slab sat on top of this weak snow. The slabs that failed were localized to near the ridgeline and tapered to nothing within about 30m of the ridge. The bed surface of the larger slide had lots of grass and sagebrush poking through it.

The first slide was a D1.5 that ran ~150m vertically (roughly 500'), stacking debris up against some small trees in the runout and breaking at least a few branches and one whole tree. I remotely triggered this from along the ridge, about 30m away from where the start of the crown opened up. The crown was roughly 30m (100') wide and 30-90cm (1-3') thick. The second and third slides weren't as wide (15-20m pockets). The initial pocket opened about 15m from where I collapsed the weak layer and the second pocket failed sympathetically roughly 50m away.

Given the sensitivity of these slabs, I suspect that they formed recently, probably within the past 48 hours. Looking at weather station data (graph included here) from the top of Baldy there is an obvious uptick in wind speed beginning late Tuesday night and lasting through most of the day on Wednesday. This was accompanied by high RH, which may have helped these dense, localized slabs form.

At this point, I'm looking at these slides as an insight into how our very weak snow surface may react to future loads (hint: poorly).

Media

This avalanche was remotely triggered from the ridgeline above. It failed on weak snow near the ground in an area with a thin, wind-affected snow pack.
This avalanche was remotely triggered from the ridgeline above. It failed on weak snow near the ground in an area with a thin, wind-affected snow pack.
This avalanche was remotely triggered from the ridgeline above. It failed on weak snow near the ground in an area with a thin, wind-affected snow pack.
7-day weather history for Baldy showing uptick in wind speeds beginning late Tuesday and continuing through Wednesday.