Avalanche forecast

West Slopes North

Northwest Avalanche Center
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Avalanche danger

Wed
Alpine
3 · Considerable
Treeline
3 · Considerable
Below
3 · Considerable
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Highlights

Dangerous avalanche conditions will exist at all elevations with strong winds, cooling temperatures, and continued snowfall. The snowpack will need time to adjust to this heavy loading event. Choose conservative terrain less than 35 degrees, and minimize exposure to large open slopes above.

Avalanche problems

  • Wind Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Likely
    Size
    2–3

    Strong south and west winds will continue over the next 24 hours, blowing snow and loading leeward slopes. The most dangerous conditions will exist in wind-loaded terrain where the potential for very large avalanches lingers. Natural avalanches even remain possible. Cornices will continue to grow and could drop onto slopes below, acting as huge triggers. Pay attention if you transition into wind-affected terrain, and look and feel for sudden changes in snow surface texture and hardness. Avoid travel on or below wind-loaded slopes 35 degrees and steeper.

    (2/22/2021) Natural avalanches on Shuksan Arm breaking 2-3ft+ deep and hundreds of feet wide. Photo: Ben Williamson

  • Storm Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Likely
    Size
    1–2

    The West North Zone received 2-3ft+ of snow since Friday, and an additional 6-12in of new snow is expected by Tuesday afternoon with snow levels dropping to 1000ft. Recent storm snow needs time to settle and stabilize, and incoming snow will thicken existing slabs and build new ones. In areas sheltered from the wind, storm slabs of varying thickness will be reactive to human traffic on slopes 35 degrees and steeper. Carefully assess the new snow as you travel using hand pits and test slopes, looking for easy fractures and shooting cracks. Seek out simple, lower-angled terrain. Avoid convex rollovers and minimize exposure to overhead hazard. 

    (2/21/2021) A skier intentionally triggered this storm slab avalanche in Swift Creek on a NE aspect at 4500ft. Photo: Phil Straub

Avalanche Discussion

A widespread avalanche cycle occurred Sunday night and Monday with numerous large to very large natural avalanches reported throughout the West North Zone. Most notable was a very large natural avalanche that hit Hwy 20 crossing both lanes outside of Newhalem near Gorge Dam at milepost 122 (see photos below). The avalanche ran on the south face of Davis Peak, one of many slide paths the WSDOT avalanche program monitors (WSDOT Avalanche Atlas, Avalanche Path Atlas Photo). Historically, this path runs at least once per winter. The avalanche likely ran for more than 4000 vertical feet, and debris flowed over mostly exposed ground with little snow cover for ~1800ft before hitting the road. Avalanches on Shuksan Arm were also impressive, breaking 2-3ft+ deep and propagating hundreds of feet wide. 

The atmospheric river event is winding down and will finish with cooling temperatures and continued snowfall. Strong westerly winds are forecast Monday night and Tuesday, and significant wind-loading is expected. The amount of recent and wind-blown snow is concerning enough, and the mid-January persistent weak layer may have been a player in recent avalanche activity, although unconfirmed. Be particularly cautious in areas near Hwy 20 and further south in the region.  

During the ongoing Covid-19 pandemic, continue to follow the latest guidance from local, state, and federal health officials. Avoid unnecessary risks that could impact first responders and stress medical resources.  Wear a mask when appropriate, practice social distancing, and consider recreating closer to home.

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