Avalanche forecast

Olympics

Northwest Avalanche Center
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Avalanche danger

Sun
Alpine
3 · Considerable
Treeline
3 · Considerable
Below
2 · Moderate
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Highlights

The first major storm of the season will raise the avalanche danger sharply Friday night, producing widespread reactive large storm slabs you can trigger on Saturday. Let the storm abate before entering avalanche terrain as storm slabs may release naturally during the early morning hours; then stick to slopes less than 35 degrees near and above treeline.

Avalanche problems

  • Storm Slabs

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

    Heavy snow, strong winds, and warming temperates Friday night will create a highly unstable storm slab. Expect 12-16" of new heavier denser snow to overly 5-6" of lower-density snow that arrived 12/8 - 12/9. A strong warm-up during the early morning hours could create a natural avalanche cycle that might extend into the early morning hours. Once the heavy rain/snow abates and cooling starts occurring, venture into the backcountry with caution. Recognize that we have added uncertainty given limited observations of a shallow, layered early-season snowpack. Avoid open slopes steeper than 35 degrees, particularly on wind-loaded aspects.  

    Example: Large (D2) slab avalanche on the east aspect of Table Mountain. The size and extent of this problem will make terrain travel challenging at Hurricane

    Photo: Lee Lazzara

Avalanche Discussion

Hurricane Ridge picked up 1" of new snow in the last 24 hours with 9" total snow depth at 5200 ft. Light winds increased into the moderate range by Friday afternoon at the Hurricane Ridge parking lot, forming very small wind drifts. Very light snowfall increased late in the day as temperatures warmed from the low to the mid 20s.

NWAC pro observers traveled by foot from the Hurricane Ridge Parking lot on Thursday. Near treeline, 75% of the terrain had sufficient coverage to produce avalanches (given instability). The snowpack structure featured 5-6" of low-density new snow (minimally impacted by wind) overlying the late-November Crust formed through repeated atmospheric river events. Sandwiched between the primary layers, the observers found a thin crust above sugary faceted snow. 

Dial back your terrain selection on Saturday. Heavy new snow and wind redistribution need time to settle. Additional snow showers with cooling temperatures should add to the avalanche size on Sunday.  Choose well-anchored slopes and terrain less than 35 degrees. Limit your time underneath slopes connected to large, wind-loaded avalanche paths throughout the day. 

 A brief period of rain below 4000 feet Friday night may mitigate avalanche danger at lower elevations on Saturday. However, at these elevations, the greatest hazard may be the early season coverage. Recognize that even a small avalanche can cause significant trauma given the shallow snow depth.

Uphill travel reminder: Check in with your local ski area this weekend regarding terrain access and parking updates. Closed ski areas often share a similar snowpack and avalanche hazard as the surrounding backcountry. You may also encounter other hazards like active avalanche mitigation, unmarked obstacles, snowmobiles, groomers, and other heavy equipment as ski areas prepare to open. Be prepared to make your own assessments and handle emergency situations.

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