Observation: NWAC Forecaster

All Observations

Basic Information

Observation Date:

December 1, 2022

Submitted:

December 2, 2022

Observer:

NWAC Forecaster - Matt Primomo

Zone or Region:

East Central

Location:

North side Cashmere, Icicle Creek (N-E 2600-4100ft)

Recent Avalanches?

Yes

Cracking?

Isolated

Collapsing?

Isolated

Signs of snowed over very soft debris off Grindstone Mtn.

Large surface hoar 25cm up from the ground associated with the 11/22 draught layer.

https://www.instagram.com/reel/ClpsfYBIgdZ/?utm_source=ig_web_copy_link

Advanced Information

Cloud Cover:

Mostly Cloudy

Wind:

Calm

New/Recent Snowfall:

~55cm since 11/25, average HS around 90cm

Nice day with cool temperatures and multiple cloud layers. Sun poked through from time to time. Wind was not strong enough to drift snow in the areas observed.

Avalanche Observation Comments:

Some difficult to discern evidence of recent, in storm activity in the form of soft slabs and loose slides in the D1-1.5 range with perhaps a few D2's in larger terrain features. Noticed a number of small loose dry slides triggered by warming or sun down at the road in the afternoon.

See video below. Average HS around 90cm, ski pen around 60cm but sometimes would sink through to near ground. Great travel conditions, somewhat difficult trailbreaking.
I could feel the lower crusts and weaker snow at the ground pretty easily with a pole probe. The crusts became thinner and the basal layers weaker once out in the open at around 3,600ft. Below that the crusts seemed thicker.
We began getting whumphing collapses at this elevation, but only on a feature that was noticeably wind loaded in the past day or two. At 3,800ft we had a large whumph that triggered other collapses further out. Failure layer was 1.5-2cm tall surface hoar over 2mm facets (11/22). In general, we were finding about 20-30cm of basal facets to be fairly consistent in our travels.

Test results NNE at 3,800ft. HS 87cm: CT5 Sudden Collapse down 62cm on large SH (11/22)
ECTP 14 down 62cm on 11/22

Problem	Location	Distribution	Sensitivity	Size	Comments
Persistent 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: 60cm Weak Layer(s): Nov 22, 2022 (FC) Comments: Could be present at other aspects, but didn't travel into those today. Most likely to trigger in areas with stiffer snow above it, such as from wind loading.

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