Avalanche forecast

West Slopes North

Northwest Avalanche Center
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Avalanche danger

Thu
Alpine
3 · Considerable
Treeline
3 · Considerable
Below
2 · Moderate
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Out of date — this forecast expired 6 years ago. You’re viewing past conditions, not the current bulletin.

Highlights

You can trigger surprisingly large avalanches on steep slopes on Wednesday. Slabs in the top couple feet may react to a human’s weight, but more concerning is a weak layer buried more than 3 feet deep. This deeply buried layer is not going away anytime soon, so continue  to avoid slopes greater than 35 degrees.

Avalanche problems

  • Storm Slabs

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

    Avalanches can occur in the new snow which fell over the weekend.  These could fail up to 2 feet deep.  They may be smaller than the deep persistent slab avalanche problem, but they could still cause injury or death.  They could also possibly trigger the deeper layer as it travels downslope, resulting in an even larger avalanche.  

    At higher elevations wind may have affected the snow, causing it to form a stiffer and more reactive slab. Observe changes as you travel, such as firmer feeling snow or drifted, pillow-like appearances. In non-wind affected areas storm slabs could react to a person’s weight, or snow may run as a loose dry avalanche in the top 6 inches or so.  With this myriad of problems, avoid slopes steeper than 35 degrees at this time. 

    (2/5/2021) Snowmobile triggered avalanche in the Mt. Baker NRA at the toe of the Easton Glacier on southerly aspect near 5000ft. The snowmobiler was caught by the avalanche and carried a short distance with their snowmobile partially burried. The avalanche looks to have failed 6-12in deep on the 2/4 interface with an impressive crown breaking several hundred feet wide.

  • Deep Persistent Slabs

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

    Avalanches can be triggered on a deep persistent layer, buried 3- 5+ feet down in the snowpack. Sadly, a snowbiker triggered an avalanche on this layer in the East Central zone on Monday, and was buried and killed. The Accident Reports page provides more details about the incident. Avalanches failed on this layer in many of the forecast zones in the last 2 weeks, with a number of them alarmingly involving people. The layer is progressively more difficult to trigger as it gets buried deeper and more time passes. Take a look at the video in the media strip to give you an idea of the depth and reactivity of the problem, which is similar to what we’re seeing in this zone.    

    At the depth this layer is buried, it is unclear whether the sole weight of a person would trigger an avalanche unless they found a shallower spot, which is possible. It is well within the depth that a snowmobile would affect. For this problem, there are no obvious signs of instability like you might find with other avalanche problems. You need to dig down to the Jan 13 crust and make note of the layer above it, observing the presence of persistent grains and how readily that layer fails. I wouldn’t place all my bets on one pit for this sort of problem. The game is too dangerous to play the odds on. Broad open slopes and large features in areas steeper than 35 degrees is where you are most likely to find the weakness, so avoid those slopes at this time. 

    (2/3/2021) A person touring along the ridgeline from Artist Point to Huntoon Point remotely triggered a cornice that fell onto the slope below triggering this large avalanche. The avalanche occurred on a NE aspect at 5000ft and failed about 1 meter deep on the 1/24 interface.

Avalanche Discussion

Avalanche problems related to new snow and wind are concerning enough, but the lingering deep slab instability poses a risk with even more uncertainty and higher consequences. A conservative mindset is crucial for getting through this period unscathed. Right now finding those lower angle areas or traveling through tighter trees are your ticket to surviving this rough period with the snowpack.  

Instabilities began after the atmospheric river event ended with a stout crust forming (Jan 13). Only a few inches of snow followed over the next 11 days, which weakened as it sat exposed to the sky. Snow began to fall Jan 24, and since then we have continued to see avalanches occurring on that Jan 24 interface. An extensive avalanche cycle occurred Jan 30- Feb 2 after a more intense period of snowfall (8.5in of water/4ft of snow at Heather Meadows), and several close calls occurred in the following days as backcountry users got out again. 

Our snowpack has some similarities with other weak snowpacks nationwide, where avalanche fatalities unfortunately had a remarkable presence in the last 10 days (16 in total). Heading out onto a steep slope for any reason is not worth the consequence of not making it home that night. Have this in mind while you travel in the backcountry during this period of unstable snow conditions.

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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