Observation: NWAC Forecaster

All Observations

Basic Information

Observation Details

Observation Date:
March 6, 2023
Submitted:
March 6, 2023
Observer:
NWAC Forecaster - Dallas Glass
Zone or Region:
West South
Location:
Crystal Backcountry, Bullion Peak, Crown Pt, Pickhandle Basin (All aspects near treeline)

Signs of Unstable Snow

Recent Avalanches? 
Yes
Cracking? 
Isolated
Collapsing? 
None Experienced

Media/Attachments

Reverse loading was evident along ridgelines. You may see wind slabs on some unusual aspects.
Reverse loading results in wind slabs in some unexpected places.
Even though they were small, intentionally triggered wind slabs ran far down slope.
An intentionally triggered shallow (4-6" deep) wind slab. This very small avalanche entrained snow and ran nearly 200 vertical feet.
Debris from an intentionally triggered wind slab. NW, 6100ft.
Large cornices loom over W aspects at present with pockets of wind slab snow just below.
Snow profile in the Crystal Backcountry.
Snow profile in the Crystal Backcountry.
A thin breakable crust formed on steep southerly aspects on 3/5. Now this layer is buried under a few inches of snow.

Advanced Information

Weather Summary

Cloud Cover:
Partly Cloudy
Wind:
Light , S
New/Recent Snowfall:
New Snow (HN24) 2-3in (5-8cm). Storm snow since 3/1 (HST) 14-16in (35-40cm).

Pretty nice day! Cool with a light breeze. Increasing clouds, but pockets of blue sky and good visibility.

I intentionally triggered 4 shallow soft wind slabs. NW 6100-6300ft SS-ASc-D1-R1-S. While these slides were small, the easily entrained the snow below and traveled several hundred feet down slope.

Snowpack Observations

Wind: There was lots of evidence of wind transported snow from this weekend's strong SE wind event. Many normal cornice lines were eroded back to nubs, and large cornices and drift were found on more westerly aspects. Light blowing snow, sharp cornices, and subtle snow surface texturing were the best clues of to wind loaded features.
I also found several older hard wind slabs on W aspects from the weekend. These generally did not produce any significant cracking, but the firm hollow snow was all I needed to see to want to avoid them.

Upper Snowpack:
We found several inter-strom layers in the upper 35-40cm of the snowpack. They typically failed in tilt tests and compression tests. The 3/1 and 2/25 interfaces however, never failed significantly in any snowpack tests where we dug.

A thin crust from 3/5's sunny weather was found underneath the new snow on steep S aspect. It was very friable and generally not noticeable.

Avalanche Problems

Problem Location Distribution Sensitivity Size Comments
Wind Slab
D1
D1.5
D2
D2.5
D3
D3.5
D4
D4.5
D5
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