Observation: NWAC Observer

All Observations

Basic Information

Observation Date:

November 26, 2021

Submitted:

November 27, 2021

Observer:

NWAC Observer - Drew Lovell

Zone or Region:

East North

Location:

Twisp River (5000'-8000')

Recent Avalanches?

Yes

Cracking?

Isolated

Collapsing?

None Experienced

Advanced Information

Cloud Cover:

Obscured

Temperature:

30°F

Wind:

Moderate , W

New/Recent Snowfall:

As of Nov 26, HST of 25cm was observed above approx. 6500', with a rapidly warming / settling HST of 10cm down to 5000'

Lt. rain at valley floor (approx. 3000') yielded to periods of s1-s2 above 5000'. Obscured skies partially cleared for the final fleeting hours of daylight. Observed evidence of steady light to moderate transport under westerly winds, resulting in stiff, isolated wind slab formation adjacent to ridgecrests.

Avalanche Observation Comments:

Observed one natural sz 1.5 windslab that likely ran overnight (Nov 25-26) from a very loaded, steep easterly col @ 7000'

Older (Oct.-early Nov.) snow persists above approx. 5500' +/- depending on slight aspect changes in the Twisp River watershed. Below this elevation, skiing is basically not happening. Above, the now strong and frozen early season snow allows for supportable and reliable travel, with subsequent accumulations providing decent turns, depending on the mood of the day and mindset of the skier.
HS varies from 70-130cm Near and Above Treeline, with the bottom 50cm or so of the snowpack consisting of frozen grains from the mid-Nov deluge.
The snowpack is generally strong and warm and continues to settle.
No layers of concern were found in a test pit on a NE aspect @ 6800' with an HS of 100cm. Tests were unremarkable.
Ski testing showed reactive to stubborn sz 1 windslabs adjacent to alpine ridgecrests, with potential propagation of a few meters, running slowly with minimal entrainment.

Problem	Location	Distribution	Sensitivity	Size	Comments
Wind Slab	N E S W	Isolated Specific Widespread	Unreactive Stubborn Reactive Touchy	D1 D1.5 D2 D2.5 D3 D3.5 D4 D4.5 D5	Layer Depth/Date: 11/26 10-40cm Comments: Reactive to ski cuts on isolated features

Likely becoming stubborn, unreactive, or obsolete as the next round of warming and heavy precipitation re-sets the landscape.

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