Observation: NWAC Forecaster

All Observations

Basic Information

Observation Date:

March 31, 2022

Submitted:

March 31, 2022

Observer:

NWAC Forecaster - Josh Hirshberg

Zone or Region:

Stevens Pass

Location:

Lichtenberg Mtn (S-SW, NW-NE. 3,400-5,844ft)

Recent Avalanches?

Yes

Cracking?

Isolated

Collapsing?

None Experienced

A small slab avalanche in a shallow, crossloaded pocket of snow. Lichtenberg Mtn, 4,760ft, NW

Small sun-triggered rollerballs coming off of rocks. Lichtenberg Mtn, 5,120ft, SW.

https://youtu.be/5FBGP37j_HQ

Advanced Information

Cloud Cover:

Obscured

Wind:

Light , NW

New/Recent Snowfall:

HST 12cm

Storm snow since the 30th averaged 12cm (5") w less below 5,000ft. Consistent S-1 snowfall. Accumulation throughout the day was insignificant but thick clouds allowed minimal sun through. Previous light drifting and cross-loading began around 5,000ft. Light blowing snow at 5,800ft ridge top.

Avalanche Observation Comments:

A few (3-4) very small D1 triggered avalanches on slopes 40deg and steeper: Two small pockets of wind slab on north aspects on the immediate lee of a ridge and a cross-loaded fan (5,800ft and 4,800ft respectively). Loose (moist) sluff on a very steep feature N, 5,280ft.
Entraining moist storm snow, these slides had some force for how shallow they were. Also saw a few rollerballs emerge from steep cliffs in the afternoon, SW, 5,100ft.

Below 4,500ft, there wasn't enough new snow for avalanche hazard. The new/old interface (3/30) was soft (4F), unfrozen polycrystals. Higher in the terrain, the interface was a crust that got thicker and harder with elevation gain. At 5,600ft, the crust was 10cm thick and almost knife hard. Wet, weak grains could still be found below it even near the ridge top.
Above 5,000ft, storm snow averaged 14cm. There were small, localized drifts of 20-25cm with isolated pockets up to 40cm deep. The lower 2-5cm of the storm snow was moist throughout the terrain and generally well-bonded to the old snow interface.

Above 5,000ft on slopes near and above 40 degrees, avalanches were easier to trigger and would entrain snow where the 3/30 crust was frozen and slick. Older frozen debris made travel challenging on some steep slopes.

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	Comments: I expect this to be more of an issue above TL. Drifts were moist and sluggish near treeline.
Wet Loose	N E S W		Unreactive Stubborn Reactive Touchy	D1 D1.5 D2 D2.5 D3 D3.5 D4 D4.5 D5	Comments: Moist lower storm snow. Needed slopes 40deg and steeper to initiate and entrain snow.

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