Observation: NWAC Forecaster

All Observations

Basic Information

Observation Details

Observation Date:
December 26, 2022
Submitted:
December 26, 2022
Observer:
NWAC Forecaster - Irene Henninger, Andrew Forsman, Bob Hopfield (WSDOT)
Zone or Region:
West North
Location:
Hwy 20 - Newhalem

Signs of Unstable Snow

Recent Avalanches? 
None Observed
Cracking? 
None Experienced
Collapsing? 
None Experienced

Media/Attachments

A south facing Sauk Mtn snowpack 4,000-5000ft, where wet snow avalanches and a lot of melting happened since warm temperatures and rain arrived.
Avalanche debris which just made it down to the road sometime near the start of the warming event. Hwy 20 near Newhalem. A lot of the debris and snow surfaces have melted out since then.
Large wet snow avalanches and glide cracks are visible in this start zone which can run down to Hwy 20 near Newhalem. SW, 4500-6500ft.

Advanced Information

Weather Summary

Cloud Cover:
Overcast
Temperature:
36°F
Wind:
Calm
New/Recent Snowfall:
1 inch of rain in last 24 hours

Weather ranged from moderate rain early to no precip later in the morning. Low lying clouds cleared as the day progressed.

Snowpack Observations

I assessed Hwy 20 as it was opening at the tail end of the large rain/warming event with WSDOT. We were surprised to see below treeline areas, and even some higher elevations, had relatively minimal snow cover. Some below treeline areas no longer had enough snow to produce an avalanche. The few higher start zones we saw showed mainly consistent snow cover and some glide cracks and old wet snow avalanches were visible on them.

Avalanche Problems

Problem Location Distribution Sensitivity Size Comments
Wet Loose
Isolated
Specific
Widespread
Unreactive
Stubborn
Reactive
Touchy
D1
D1.5
D2
D2.5
D3
D3.5
D4
D4.5
D5

Warming event 12/23 started with wet loose avalanches before shifting to wet slab and/or glide avalanches. Evidence of avalanches we saw were likely from start of warming event. We saw very small avalanches which just ran on small road cut banks to very large avalanches which ran down gullies from above treeline start zones to below treeline.

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