Date of Observation: 12/21/2020
Name: Eric Murrow

Zone: Northwest Mountains
Location: Sunnier side of Baldy
Aspect: East, South East, South, South West, West
Elevation: 9,500′ – 11,800′

Avalanches: While heading out Slate River Road noticed two unreported avalanches on the far end of Schuylkill Ridge and the sub-peak of Schuylkill Mountain. Both avalanches were easterly near-treeline features. I suspect they ran on Saturday or Sunday. Both D1.5’s
Weather: Sunny day, with mild to warm temperatures with light winds near and below treeline.
Snowpack: Recreational ski day just enjoying the sun. Southerly slopes near and below treeline had a soft melt-freeze crust at the surface in the morning that became moist throughout the day (exited terrain by 1pm). I suspect supportive melt/freeze crusts will develop from today and tomorrow’s forecasted mild weather on steep, sunny slopes near and below treeline. Lots of collapsing on low-angled south-facing slopes that are of little concern. More concerning was walking around the top of small east-facing, near treeline features, I was able to produce a collapse that shook a small wind-lip well over 100 feet away – slope was only 25 – 30 degrees steep so it did not slide (it took a bit of wandering around until I was able to produce the collapse, classic PSa behavior). Briefly moved over several west-facing near treeline features and produced a collapse on each but slopes angles were only about 30 degrees so nothing moved.
Skied several short steep south and southwest facing features without result, quick pole probing did not reveal any concerning structure.

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Date of Observation: 12/21/2020

Zone: Northwest Mountains
Location: Red Lady Bowl, Skier’s right side
Aspect: East, South East
Elevation: 12100

Avalanches: A preliminary report from the roadside: 2 avalanches observed at 0732 in Red Lady Bowl on the skier’s right side of the bowl. One medium, one small slide started near the summit. Unknown if skiers are on the slope
Weather:
Snowpack:

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Date of Observation: 12/20/2020

Zone: Northwest Mountains
Location: We were on anthracite Mesa heading up Coney’s.
Aspect: West
Elevation:

Weather: Although weather was clear, we witness some wind loading coming from the north.
Snowpack: With the persistent slab snowpack we witnessed layer collapsing on just about every new snow feature we came upon. While ascending one at a time on a slope that measured at about 30 degrees the snow pack collapsed and cracked. Had it been a slope greater than 30 it would have slid.

Zone: Northwest Mountains

Location: Irwin Tenure

Date of Observation: 12/20/2020

Subject: More activity at Irwin and on Owen

Aspect: West

Elevation: NTL

Avalanches:

Natural activity on East Face of Owen from the recent wind shift: HS/SS-N-R2/D2-O on Owen from last night. Lee (to recent veering) cross-loaded wind slab ran and pushed out a small PS. Broad initial crown running long.

Still very touchy above critical slope angles on WW
Sunset Left SS-AE-R3-D2-O FC (65cm x 30m x 100m) Sunset left remotely triggered moonrise right
Moonrise Right SS-AE-R1-D1-O FC (40cm x 10m x 30m)
Moonrise Left —-  Small pocket up high sympathetically triggered far out

Weather:

Snowpack:

Zone: Northwest Mountains
Location: Ruby Range
Date of Observation: 12/20/2020
Name: Zach Kinler

Aspect: East

Elevation: Above Tree Line

Avalanches:

This picture from Baxter Basin was passed on to the CBAC sfaff.

2 large persistent slab avalanches on East aspects of Richmond Mt. Both of these initiated from ridgeline and quickly stepped down to weak layers in the lower snowpack. Debris from both avalanches triggered additional slab avalanches lower in the track.

Zone: Northwest Mountains

Date of Observation: 12/20/2020

Subject: Fresh naturals continue

Aspect: East

Elevation:

Avalanches:

A few apparent wind slabs in steep shallow East facing terrain above Redwell

Weather: The wind had been doing some work overnight and during the day today.

Snowpack:

Photos:

Zone: Northwest Mountains

Date of Observation: 12/20/2020

Subject: Wind slabs

Aspect: South East, South

Elevation: N/ATL

Avalanches:

Spotted a few more recent persistent slab avalanches fitting the usual pattern.

Weather: Moderate ridgetop winds. High clouds thinned through the day.

Snowpack: Rec skiing on southerly aspects to take a break from looking at persistent slabs. We had to manage for small windslabs that were easy to identify and avoid. Wind drifted slabs were 8” to 10” thick near treeline, easy to produce cracking on moderate slope angles. Above treeline, wind slabs were up to 18” thick and harder (1F) and more stubborn. These were all cracking on lower density snow from earlier in the week. We also got several rumbling collapses on lower angle terrain where buried sun crusts (2 feet deep) are thinner than on steep aspects. The basal structure transitions from a strong crust on steep south to a thinner, weaker, more collapsible crust on ESE.   We avoided drifts and stayed on more southerly pitches with no avalanche activity.

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