Observation: NWAC Forecaster
Basic Information
Observation Details
Observation Date:
December 26, 2021Submitted:
December 26, 2021Observer:
NWAC Forecaster - Irene HenningerZone or Region:
West CentralLocation:
Lake 22 (N - E, 1000-2000ft)Signs of Unstable Snow
Recent Avalanches?
YesCracking?
None ExperiencedCollapsing?
None ExperiencedMedia/Attachments
Advanced Information
Weather Summary
Cloud Cover:
OvercastTemperature:
24°FWind:
CalmNew/Recent Snowfall:
35cm overnight @ 2000ftS5 (heavy) snowfall, with about 2 feet of low-density snow available for transport. Temperatures were cooling from 26-23F during the hike.
Not long after entering a meadow just below 2000ft, I encountered a small fan of avalanche debris which I suspected was caused by a tree bomb not far above. It was a challenge to make my way through/over the approximately 8 ft wide, 3 ft deep soft pile on foot. The trail switchbacked and I encountered more debris adjacent to the tree - the debris came not from a tree bomb but from an avalanche overhead. I couldn't see the track at all due to snow already covering it up, although I suspect it had occurred in the last hour or two. I decided to turn back, as it was snowing heavily and I would not be surprised if another avalanche came down while I traveled through similar terrain for the next several hundred feet. I didn't think an avalanche would be large enough to bury me, but the meadow was bony and even a small ride wouldn't have been fun. I was also by myself- not ideal. The track was very irregular, with rocky bumps and brush exposed.
Snowpack Observations
It snowed to low elevations and the Snohomish County Jeepers were out on the Mtn Loop Highway in full force. At the Lake 22 Trailhead (1000ft) there was about 2 feet of snow, with 6" of fresh overnight. Upon reaching an open meadow just below 2000ft, there was at least a foot of new snow overlying the previously packed singletrack. 3-4 feet of snow was on the irregular surfaces off to the sides of the trail.
Walking back from the meadow I did informal hand shear tests. The steep snow piles to the side of the trail were perfect: I could run my hand through the surface near the top of the slope and the entire area beneath it would run down onto the trail, about 4 inches deep. I suspect this shallow layer is what the avalanche ran on. The top 2 feet of snow was very low hardness (fist), and snow was low hardness (4finger) beneath that. No other weaknesses were found in the top 3 feet.
Avalanche Problems
| Problem | Location | Distribution | Sensitivity | Size | Comments |
|---|---|---|---|---|---|
Dry Loose
|
|
Layer Depth/Date: 12/26/21 Comments: Touchy shallow (4") dry loose avalanches, mostly remaining very small. Unknown at higher elevations. |