Observation: NWAC Forecaster

All Observations

Basic Information

Observation Details

Observation Date:
February 15, 2023
Submitted:
February 15, 2023
Observer:
NWAC Forecaster - Andy Harrington
Zone or Region:
Snoqualmie Pass
Location:
Chair Peak - North Slope

Signs of Unstable Snow

Recent Avalanches? 
Yes
Cracking? 
Isolated
Collapsing? 
None Experienced

Media/Attachments

Slabs in higher elevation terrain that likely failed during the 2/13 avalanche cycle. Some of these may have filtered into a popular skiing couloir that had a large debris pile below it.
Rollerballs coming out of steep terrain, often shedding from trees and rocks on sun exposed slopes.
Wind sculpturing near ridgelines produced fins, "fat" areas, and other drifts.
Wind textured surfaces at upper elevations near ridgeline. Convex features in the background also showed signs of wind-loading.
A slab lower down on a slope, but still below rocky terrain that likely failed during the 2/13 storm.
A slab on a steep unsupported slope that likely failed during the height of the storm on 2/13.

Advanced Information

Weather Summary

New/Recent Snowfall:
No new snowfall

Beautiful blue skies with sunshine and fairly calm wind. Just a few gusts here and there.

Observed some new Wet Loose avalanches on steep slopes that see sunshine as we exited the field around 12:30. Plenty of older crowns from the cycle on 2/13 were spotted, most of them are at least partially filled in.

Snowpack Observations

Today I traveled up the Alpental Valley, climbed up Chair Peak, past the Thumbtack, and over to the North Slope. Took a lap down to the natural bench above the cliffs before coming back up and skiing the North Slope proper down to Snow Lake. Crossed the lake, up over the divide, and back to the car.

The approach on the sun exposed southerly slopes of Chair held a breakable sun crust in the morning. As we crested the ridge, we were greeted with plenty of signs of recent wind-effect. Textured surfaces, wind-pressed snow, and a shallow wind-skin/slab were found near ridgelines. I was able to get some blocking to fail during uptrack tests but didn't trigger any actual Wind Slabs. That said, the amount of wind effect was enough to keep me from skiing certain terrain, so maybe that's why I didn't find a slab. As we descended away from the ridgeline, the wind's influence was less noticeable and we found rapidly settling storm snow. The settlement was noticeable compared to the day prior.

On the exit back to the car via the southerly slopes in the sun, the crust had broken down and the snow was much heavier. We noticed some new Wet Loose avalanches had occurred over the few hours we were in the shade.

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