Bollettino valanghe

West Slopes South

Northwest Avalanche Center
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Pericolo valanghe

Sat
Alta quota
2 · Moderato
Limite del bosco
2 · Moderato
Sotto il limite
1 · Debole
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In sintesi

With a few inches of new snow and a warm sunny day, you may see piles of rollerballs and maybe even a few natural loose wet avalanches. While most of these slides should stay small, if they entrain older wet snow they could grow large and destructive. This is most likely to occur in very steep rocky terrain. 

Problemi valanghivi

  • Loose Wet

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

    The West South zone picked up a few inches of snow Wednesday night. While there was some sunshine on Thursday,  clouds lingered in many areas. That won’t be the case Friday. We’re expecting the sunniest day so far this week. As a result, you’ll likely see rollerballs and maybe even a few natural loose wet avalanches in the new snow. These slides should stay pretty small unless they entrain older wet snow. Below the surface, the upper snowpack remains wet and weak. While it is very unlikely, one of these larger avalanches could occur, particularly in rocky terrain. Be leery of large complex slopes at mid and upper elevations if you find the upper snowpack isn’t frozen underneath the most recent snow.

    (1/16/2022)

    Example:  Natural wet loose avalanches on an east aspect near 6800ft on Hogback Mountain.

    Photo: Public Observation

Avalanche Discussion

After a few final flurries Thursday night, our week of active weather will finally draw to a close. Lingering low clouds Friday morning should quickly give way to mostly sunny skies and warming temperatures. While most locations received 2-5” of snow during this last round of precipitation, below the surface, the wet snowpack hasn’t had a good opportunity to freeze following Monday’s deluge. As a result, it remains rather weak and unconsolidated below an often breakable crust. This isn’t likely to change until we have a cold clear night to help the snow really gain strength. 

An impressive atmospheric river took aim at the Washington Cascades and the West South zone Feb 28th. Rain reached near the top of our forecast area and soaked the snowpack. Sites around the zone received 5- 7.5” of precipitation, 4-5” of which fell as rain near treeline. Not surprisingly, a widespread avalanche cycle ensued. “There’s debris everywhere from earlier this week.” said one local avalanche professional. Some wet slab avalanches even failed on older snow layers like the 2/19 and Valentine’s Day crusts. Continued stormy weather limited our ability to gather information and fully understand the extent of this cycle. However, avalanches were reported from near Crystal Mt, Mt Rainier, White Pass, and Mt St Helens. 

Now that the cycle has ended and the snowpack is draining, we’re left with a variety of snow surfaces. You could encounter wet heavy snow, breakable crust, bumpy rain runnels, and icy slopes. Creeks and waterfalls are roaring as the recent rain still works its way through the landscape. Make sure you give yourself extra time to navigate some of these potentially challenging travel conditions. 

At the highest reaches of our forecast area (7500-8500’), you may find yourself above the rain line from the storm. If you encounter deeper dry snow, consider any steep wind-loaded slope suspect. We do not have any recent information from these higher elevation areas.

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