Observation: NWAC Forecaster

All Observations

Basic Information

Observation Details

Observation Date:
February 20, 2022
Submitted:
February 20, 2022
Observer:
NWAC Forecaster - Dallas Glass
Zone or Region:
West South
Location:
Hogback Mt./ White Pass Backcountry (NW-E-S, Near and Below Treeline)

Signs of Unstable Snow

Recent Avalanches? 
Yes
Cracking? 
Isolated
Collapsing? 
None Experienced

Media/Attachments

Snowprofile on a shaded slope in the White Pass backcountry.
A shovel tilt test that failed between the 2/19 interface and Valentine's Day crust about 12" below the surface. N aspect, 6400 ft.
A snowprofile in the White Pass backcountry on a slope that receives sunshine.
Shooting cracks in a wind loaded area near the top of Hogback Mt. These cracks are 6-8 ft long.
Uptrack tests porduced lots of short cracks in the storm snow. These failed near the base of the new snow above the 2/19 interface.
Rime, textured snow surfaces, and blowing snow all showed winds were loading slopes just over the ridge and out of sight.

Advanced Information

Weather Summary

Cloud Cover:
Overcast
Temperature:
28°F
Wind:
Moderate , NW
New/Recent Snowfall:
8-10" (20-25cm) with substantial wind transport.

Snow showers all day with periods of moderate snow (S2). Occasional sun breaks were very short-lived. The snow did not significantly impact the snow surface. Moderate NW winds were easily transporting snow.

Avalanche Observations

 #  Date Location Size Type Bed Sfc Depth Trigger Photos Details
2 Feb 20, 2022
() 		Gunsight Chutes
NE 6200ft 		D1
R1 		SS-Soft Slab 0.5ft N-Natural
Sharp cornices and shallowly buried debris from a small natural avalanches that occurred overnight in the Gunsight Peak area. Another similar slide was seen in the chute to the NE. 6200ft. NE. SS-N-R1-D1-S, 6" deep.
Report
Gunsight Chutes

I observed 2 small natrual storm slab avalanches on Gunsight Peak. Both occurred overnight and had a few inches of new snow covering the crown/bed-surface. These slabs were about 6" deep. NE, 6200'.

While visibility was very limited today I did not see any other avalanches during periods of sunshine.

Snowpack Observations

Storm snow: 8-10" (20-25cm) with significant wind redistribution. This created scoured slopes and drifts up to 18-20" (45-50cm). The storm snow was fairly well bonded to the old surface (2/19). Handpits, up track tests, and small column snowpack tests all failed about 1" (2cm) above the 2/19 crust. However, small slope and large column snowpack tests did not show signs of propagation were likely.

Wind slabs: small pockets of wind drifted snow were seen along exposed ridgelines. While these slabs produce shooting cracks, they did not avalanche in any small slope test. With the winds out of the NW, the predominately wind-loaded aspects were E-SE-S. Many normally loaded NE slopes were stripped by the NW winds.

Shaded Slopes: On shaded slopes, the snowpack still contains several very well preserved layers. This much colder, drier, and weaker snowpack stands in stark contrast to slopes that receive sunshine. My primarily layer of concern on shaded slopes was a layer of weak (faceting) snow between the very thin and breakable 2/19 crust and the thicker Valentine's Day crust. This layer did fail in some snowpack tests, but failures were resistant and large column tests did not propagate.

Sunny Slopes: Sunny slopes now includes due E and W terrain. The new snow is well bonded to the 2/19 interface. Below the 2/19, the snowpack has undergone numerous melt-freeze cycles. So, while i could identify the Valentine's Day Crust and Late January crust, they had generally been incorporated into one large block of very strong and icy spring-like (melt-form) snow.

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