Observation: NWAC Forecaster

All Observations

Basic Information

Observation Date:

March 15, 2022

Submitted:

March 15, 2022

Observer:

NWAC Forecaster - Josh Hirshberg

Zone or Region:

East North

Location:

Kangaroo Ridge (SW-NW, 2,400-7,200ft)

Recent Avalanches?

Yes

Cracking?

Widespread

Collapsing?

None Experienced

A small (D1) slab avalanche, triggered on a leeward slope on the 3/14 interface. Crown: 14" deep x 25' wide. Insert- Crack adjacent to crown. Kangaroo Ridge, WNW, 6850ft

A tilt test breaking on a 3/15 mid-storm interface, 10" (25cm) below the surface. Kangaroo Ridge, WNW, 6720ft.

A crack breaking thru wind-drifted snow. Kangaroo Ridge, WNW, 6,600ft

A small (D1) slab avalanche, triggered on a leeward slope on the 3/14 interface. Crown: 14" deep x 25' wide. Kangaroo Ridge, WNW, 6850ft

Advanced Information

Cloud Cover:

Obscured

Wind:

Moderate , SW

New/Recent Snowfall:

30cm @ Hairpin by end of day

Stormy day w consistent snowfall, periods exceeding S2. Snow as low as 3,500ft, Silver Star TH. Poor visibility. Subtle wind transport near treeline. Mild temperatures kept us soggy. Clearing skies east of Cutthroat creek in the late afternoon.

#	Date	Location	Size	Type	Bed Sfc	Depth	Trigger	Photos	Details
5	Mar 15, 2022 ()	Cutthroat paths, WA Pass Hwy 20 NE ft	D1.5	WL-Wet Loose	I-New/Old Interface		N-Natural		Report
2	Mar 15, 2022 2:30 am ()	Kangaroo Ridge NW 6850ft	D1 R2	SS-Soft Slab	I-New/Old Interface	1ft	AS-Skier		Report

Map of listed avalanches:

Cutthroat paths, WA Pass Hwy 20

Kangaroo Ridge

Avalanche Observation Comments:

We triggered small avalanches where the wind drifted slabs of fresh snow on leeward NW slopes above 6,500ft. At 15:30, we thought we heard a natural avalanche in the Hairpin valley. Parties in the Hairpin valley reported hearing and seeing natural avalanches to size D2 and triggering very reactive loose dry avalanches on wind-sheltered northerly aspects.

Storm snow was only cohesive where it was wind-drifted. Below 6,000ft, lower 10cm of HST was moist. Near treeline, found harder (F+) layer in the lower 10cm of storm snow.
Above 6,000ft- 3/14 interface varied from:
On previously wind-scoured, sun-exposed slopes- very slick and stout crust from 3/1 AR event (early March crust)
On previously wind-sheltered solar aspects- thin/weak crust w underlying facets resting on the early March crust (buried 3/3)
On previously winds wind-sheltered or loaded northerly aspects- small (0.3-0.5mm) near-surface facets above the early March crust (buried 3/3)

Profile- WNW, 6720ft, 33*, HS 240cm
Notable tests:
↓25cm- Easy, planar tilt test on DF, 3/15 mid-storm interface
↓33cm- CTM(RP), ECTN12 on 1.0mm DF(FCxr), 3/14 new/old interface
↓81cm- ECTP16 on 1.0-2.0 FCsf, 2/26? interface
↓95cm- CTM(SP) on 2.0mm FCxr (very rounded), late Jan pwl (Jan 20th)

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: 3/14 new/old interface ↓35cm NTL Comments: NTL-immediate Lee slopes.
Dry Loose	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: 3/15 mid-storm, and 3/14 new/old
Deep 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: Late Jan pwl ↓70-100cm, also 2/26 FC ↓80cm Weak Layer(s): Jan 30, 2022 (FCsf) Feb 26, 2022 (FCsf) Comments: Trending to just northerly aspects. CTM(SP) ↓95cm on 2.0mm FCxr (very rounded). 2/26 FC very sharp and angular