Observation: NWAC Forecaster

All Observations

Basic Information

Observation Details

Observation Date:
April 11, 2023
Submitted:
April 11, 2023
Observer:
NWAC Forecaster - Andy Harrington
Zone or Region:
Snoqualmie Pass
Location:
Alpental Valley - Draft Dodger Ridge

Signs of Unstable Snow

Recent Avalanches? 
Yes
Cracking? 
Isolated
Collapsing? 
None Experienced

Media/Attachments

Wet avalanche debris coming out of the Bryant Peak Couloir and from Chair Peak was observed from Source Lake in the Alpental Valley.
Boot penetration was knee-deep in most locations helping highlight that the underlying moist snow did not freeze overnight.
Avalanche debris and a crack on a convex rocky slope near "Unicorn" in the Alpental Valley.
A frequent Glide slope at the Alpental Ski Area has not yet released during this rainy period, but the crack continues to loom large.
A snow profile highlighting different moisture content within the upper snowpack. The wetting front was roughly 2 feet below the surface.
A frequent Glide slope near Alpental Ski Area known as Shot 8 had plenty of debris and some cracks, but has not yet fully released its wintertime snowpack.
A skier-triggered slab in the new snow on a convex slope. There was just enough energy and distance for the slide to start to gouge down into moist snow below.
Wet avalanche debris in a popular gully for uphill and downhill travel in the Big Trees area of the Alpental Valley.

Advanced Information

Weather Summary

New/Recent Snowfall:
7-9 inches at upper elevations; only a few at lower

Light to moderate snow showers throughout the morning with minimal wind. Terrible visibility. Down at the truck, temperatures crept slowly upward and precip was more snain-like when I returned around noon. The sun was just starting to break through as I left the Pass.

Despite the poor viz, I noticed numerous wet debris piles throughout the valley. Notable locations: Shot 8, Bryant Peak Couloir, Chair Peak Apron, No Fog, Big Trees, Unicorn, Mushroom Couloir, Mushroom Cliffs.

I also was able to trigger a few Storm Slab/Wind Slab avalanches in the new snow on convexities on Draft Dodger Ridge. They failed fairly easily with ski cuts and in one case ran far enough to just start to entrain moist snow below.

Snowpack Observations

Surprisingly, the new snow was not well bonded to the underlying snow surface, which was moist/wet. It failed easily in hand pits and on test slopes as mentioned above.

There was no overnight freeze anywhere I traveled today - boot pen roughly knee-deep and ski pen approaching a foot deep in many locations.

Digging on Draft Dodger around 4600 feet, I found the wetting front to be about 2 feet below the surface including roughly 17 inches of large wet grains. Below the wetting front, drier snow existed with older layers still visible. As is often the case, the depth and uniformity of wetting were inconsistent across the landscape.

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