Observation: NWAC Observer

All Observations

Basic Information

Observation Details

Observation Date:
December 30, 2022
Submitted:
December 30, 2022
Observer:
NWAC Observer - Brooke Maushund
Zone or Region:
Stevens Pass
Location:
Moonlight and Yodelin Areas (NW & E)

Signs of Unstable Snow

Recent Avalanches? 
Yes
Cracking? 
None Experienced
Collapsing? 
None Experienced

Media/Attachments

~30cm of upside down storm snow on top of a stout ice crust at 3600' on NW aspect. ~8cm of 4f snow on top of 22cm of fist snow.
Recent D2 avalanche in the E-facing Moonlight area.

Advanced Information

Weather Summary

Cloud Cover:
Overcast
Temperature:
28 rising to 36°F
Wind:
Moderate , SW
New/Recent Snowfall:
HN 30cm

Significant wx factors to note: more snow than forecasted fell throughout the day, with the new snow coming in largely "upside down" — in cold conditions, then warm conditions on top of that. As the day progressed and the temperatures increased, the snow surface because much more moist than the snow just 10-15cm below.

Avalanche Observations

 #  Date Location Size Type Bed Sfc Depth Trigger Photos Details
1 Dec 30, 2022
() 		Stevens Pass - Moonlight Area
E 4100ft 		D2
R2 		SS-Soft Slab I-New/Old Interface N-Natural
Recent D2 avalanche in the E-facing Moonlight area.
A natural slab avalanche with a crown over 200ft wide. Skyline/Moonlight area E, 4,600ft. Photo: Liz Riggs-Meder
Report
Stevens Pass - Moonlight Area

We observed a D2 avalanche on E-facing slope at ~4100', likely a product of the new loading of the storm snow (see photo)

Snowpack Observations

The storm snow largely came in upside down, with 30cm of upside down storm snow on top of a stout (K) ice crust at 3600' on NW aspect. 8cm of 4F snow on top of 22cm of F snow above the Christmas rain crust. Cohesion of storm snow indicated further caution around the storm slab problem would be prudent. Christmas rain crust was supportable on skis, however boot pen averaged 25cm

Avalanche Problems

Problem Location Distribution Sensitivity Size Comments
Storm Slab
Layer Depth/Date: 30cm down from surface
Weak Layer(s): Dec 25, 2022 (MF)

Was instructing an AIARE Rescue course, so we stayed below treeline. We did observe some sslabbing of the new storm snow, but did not get into wind-affected areas to observe data around the wind slab problem.

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