Bollettino valanghe

Olympics

Northwest Avalanche Center
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Pericolo valanghe

Sun
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3 · Marcato
Limite del bosco
3 · Marcato
Sotto il limite
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In sintesi

Another day of hot and sunny weather will continue to weaken the snowpack and cause it to become wet and unstable. Plan to travel and return early. Choose routes that limit the amount of time you spend underneath large and complex slopes.

Problemi valanghivi

  • Glide Cracks

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Possible
    Dimensione
    2–3

    Over in the Cascades, several large (D2) and very large (D3) avalanches occurred on Friday. We know the terrain in the Olympics has the same potential. After so many hot days, water is moving in the snowpack and in many cases reaching the ground. Glide slabs can fail without warning at any time of the night or day. Avoid traveling on or underneath any slope where you see crevasse-like glide cracks.

    (4/16/2021) A glide avalanche which occurred Thursday (4/15) night on Goat Mountain's West Peak. The crown is well over 10 feet deep. Photo: Andi Nelson

  • Loose Wet

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Likely
    Dimensione
    2

    After a 4th night of above freezing temperatures, large natural avalanche may occur. These won’t be small loose wet slides. Avalanches may entrain significant amounts of wet heavy snow, gouge into older layers, and travel far downslope. Pay attention to small signs that the snowpack is primed and ready. Snow shedding from rocks and small point-release slides can serve as clues before these larger events unfold. Pay attention to the slopes above you, and limit the time you spend traveling in and underneath large avalanche paths. 

    While the primary concern stems from large natural avalanches, you may trigger wet slides on slopes greater than 35 degrees. Any thin crust that forms overnight won’t last long in the hot and sunny weather. Once you punch into the snow past your ankle, it’s time to change locations. Find lower angled or slightly more frozen snow to avoid triggering a loose wet slide.

    (4/16/2021) Example: A large natural wet loose avalanche which occurred in the last 24 hours on Cathedral Crag on a southeast aspect at 5000ft.

Avalanche Discussion

Considerable danger with loose wet avalanches seems very normal at first glance. However, this stretch of hot and sunny weather will likely lead us into the first widespread spring shed cycle of the year. Saturday will start after the 4th night in a row of above-freezing weather with temperatures forecasted to climb into the 50s or even 60s. These simple red flags highlight the potential for dangerous conditions. 

During these spring events, many types of avalanches can come into play. Cornices grew large all winter and now sag along many ridgelines. They may collapse over the weekend, entrain snow, and/or trigger other avalanches. Below the surface, many layers still exist within the snowpack where water could pool and cause a wet slab. Predicting when, where, and what type of wet spring avalanche you may encounter is incredibly challenging. Fortunately, the travel advice during these shedding events is the same. Travel and return early before the danger increases dramatically. Choose routes with plenty of options to adjust to the rapidly changing spring conditions. This includes making sure you have a safe route back to your car. Pay attention to the terrain above you. It may warm quicker than where you travel. Use routes that help limit your exposure to large and complex avalanche terrain, especially during the heat of the day. 

Daily avalanche forecasts will end on Sunday, April 18th.

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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