Observation: NWAC Forecaster

All Observations

Basic Information

Observation Details

Observation Date:
November 28, 2022
Submitted:
November 28, 2022
Observer:
NWAC Forecaster - Dallas Glass
Zone or Region:
West South
Location:
White Pass Backcountry (W-N-SE Below and Near Treeline, 4500-6300ft)

Signs of Unstable Snow

Recent Avalanches? 
Yes
Cracking? 
None Experienced
Collapsing? 
None Experienced

Media/Attachments

A small intentionally triggered soft slab avalanche in the White Pass backcountry. 6300ft, E, SS-ASc-D1-R1-S, 6-8 in deep.
Intentionally triggered loose dry avalanche in the White Pass backcountry.
Snowprofile in the White Pass backcountry near Gunsight Peak.
Snow (or lack there of) in the trees can serve as a great clue to help you locate potentially wind loaded slopes.
Human triggered small loose dry avalanche. While small this slide ran a long way. White Pass backcountry. 6200 ft, E asp, L-ASc-D1-R1-S

Advanced Information

Weather Summary

Cloud Cover:
Overcast
Temperature:
20°F
Wind:
Moderate , W
New/Recent Snowfall:
New (HN24): 6-8 in (15-20cm), Snow since 11/25 10-15 in (25-40cm)

Generally a nice cold day. Winds were only really noticeable on exposed ridgelines and wind-transported snow was minimal.

I was able to intentionally trigger 4 small (D1) loose dry avalanches on very steep (>40) NE-E facing slopes. One of these slides did propagate and produce a shallow (8in) soft slab. L-ASc-D1-R1-S x4. All of these slides ran to near the bottom of the paths.

Snowpack Observations

Below Treeline: Snow depth (HS): 15-24in (40-60cm). About 10-15 in (25-40cm) is right-side-up storm snow since 11/22. The lower snowpack is very strong melt-forms from several rain events.

Near Treeline: Snow depths (HS) 28-40 in (65-100cm), about 13-18 in (35-45cm) is right-side-up storm snow since 11/22.
Storm snow interfaces exist, including a layer of graupel. However, failures were inconsistent.
11/22 Interface is a very stout but thin (1in, 3cm) rain crust.
The lower snowpack is a mix of melt-freeze crust, pockets of facets, and strong rounded grains.

Wind transport: Signs of wind-transported snow were evident. However, wind slabs were very soft and did not produce any avalanches. However, I was unable to travel to higher, more wind exposed, areas.

WordPress Lightbox