Bollettino valanghe

West Slopes South

Northwest Avalanche Center
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3 · Marcato
Limite del bosco
3 · Marcato
Sotto il limite
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In sintesi

Dangerous avalanche conditions will persist across the West South zone on Sunday. Recent avalanches are the best indication that the snowpack is unhappy, and we have had a ton of them this week. Minimize your exposure by sticking to small slopes and treed terrain.

Problemi valanghivi

  • Storm Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Likely
    Dimensione
    1–2

    This week, several rounds of precipitation and wind have created multiple potential failure points in the upper snowpack. Another storm on Sunday will continue that trend. Given the right slope and trigger, any number of those interfaces could fail.

    You can use test slopes or hand pits as you travel, but they likely will only give you information about the very top of the snowpack. You won't be able to adequately investigate layers from earlier this week that haven't had a moment to rest. For that, you'll need your shovel. Look for heavy snow over weak snow (upside-down snowpack) or easy failures in cohesive blocks to help indicate a slab avalanche problem.

    Of course, recent avalanches are the number one red-flag of instability, and you should be able to spot one from this week almost anywhere you travel in the backcountry. Don't ignore these warnings - the snowpack has been under constant duress this week and needs time to heal. Help it out by avoiding slopes over 35 degrees where triggering a slide is more likely. 

    (12/27/2024)

    A large natural avalanche in Pickhandle Basin near Crystal Mountain. This one has a clean look to it, meaning it likely occurred after the height of Thursday's storm.

Avalanche Discussion

We've been in a storm cycle since Christmas Day in the West South zone, and Sunday will be no different. During this period, weather stations around the zone have recorded roughly 5 inches of water on the volcanoes, and half that amount near the crest. Height of snow measurements have increased anywhere from 2-3 feet and wind speeds have touched 90 mph at times. On Sunday, it will be another day, another inch of water for the volcanoes. Near the crest, we're looking at about 0.75 inches of water. Winds should increase throughout the day and change direction, so look for loading on a variety of aspects. White Pass will likely join Chinook and Paradise in the 100-inch club.

It shouldn't be hard to imagine that so much recent snow has led to widespread avalanche activity. Reports of natural, human, and explosive-triggered avalanches large enough to bury and kill you have been rolling in consistently this week. On Saturday, a human-triggered slide broke widely about a foot deep on Pan Face at Paradise. There were also wet avalanches, some of which, gouged to the ground at lower elevations.

Unfortunately, there are a lot of slides that likely happened this week and we'll never know about due to constant storms burying their evidence. Don't assume a slope is safe just because it has already slid this week. They can reload and release multiple times with all this snow and wind. The threat of natural avalanches may have lessened but hasn't been eliminated. They will be more likely during or shortly following periods of heavy precipitation rates or strong winds.

Freezing levels should lower with this storm pulse, so hopefully you won't have to worry about wet avalanches down low. But keep them on your radar anywhere you encounter a wet surface or rain falling on dry snow.

The stout Solstice Crust can be found 2-4 feet down and is considered a "new ground" from our perspective. Any avalanche should be confined to the snow above this easily identifiable layer. 

With so much recent snow, it's time to bring up snow immersion suffocation and tree well safety. Keep your partners in sight and read up about deep snow issues.

Regioni coperte