Lawinenlagebericht

Lawinenlagebericht

Payette Avalanche Center
Auf der Karte ansehen

Lawinengefahr

Hochgebirge
3 · Erheblich
Waldgrenze
3 · Erheblich
Unterhalb
3 · Erheblich
Veraltet — dieser Lagebericht ist 6 years ago abgelaufen. Du siehst vergangene Verhältnisse, nicht den aktuellen Bericht.

Kernpunkte

Avalanche danger will be rising today. New snow, moderate to strong Southwest winds, and rising temps will put stress on our snowpack that has a slab overlying weak faceted snow.  Avoid wind loaded slopes, and slopes steeper than 30 degrees. Pay attention to red flags like cracking and whumphing. Stay far away, and out of run out areas and steep slopes, especially wind protected areas where surface hoar is buried and better preseved. Be cautious of early season conditions like exposed rock and logs.

Lawinenprobleme

  • Persistent Slabs

    • Hochgebirge
    • Waldgrenze
    • Unterhalb der Waldgrenze
    Wahrscheinlichkeit
    Possible
    Größe
    1–2

    A variety of weak layers exist within our snowpack.  If you take the time to dig a quick hasty or hand pit as you travel, you will see a combination of buried surface hoar and near surface facets present in the upper snowpack 6-12 inches down from the surface.  In some areas there are multiple layers of surface hoar.   An obvious thick layer of  loose,  faceted, very weak snow is the weak layer collapsing and whumphing in most areas and is a result of the early November snow that litterally rotted out during the extended high pressure over the last few weeks.

    This week's new snow was not quite enough of a load in most places to overload these layers so they are still waiting  for a trigger.  Additional snowfall combined with good wind for loading over the next 48 hours could be that trigger, but a great take home point is that if we don't see natural avalanches associated with this next storm,  that does not mean the snowpack is safe or stabilizing.  These weak layers will not be going away until we have a significant loading event or they are triggered by a skier or snowmobilier.  Incremental or small storm total loading is a bad scenario, it allows the slab  weak layers to  slowly grow in size, increasing the size of a potential avalanche until it is triggered.

    Basic bad setup yesterday at Big cr Summit: Slab over weak faceted snow.

  • Wind Slabs

    • Hochgebirge
    • Waldgrenze
    • Unterhalb der Waldgrenze
    Wahrscheinlichkeit
    Possible
    Größe
    1–2

    Wind slabs formed in some areas earlier this week, and will be growing today, and may possibly fail naturally or with a trigger like a skier or sledder.  Cracking snow under your skis or sled  or shooting away from your skis or sled are obvious warning signs of this.  Visual clues like drifted or sculpted snow will also let you know what the wind has been doing and where.  Sudden changes in consitency of the snowpack from soft to firm or hard  across a slope is also another great clue. You are most like to find sensitive wind slabs near ridgetops or in other wind exposed areas.

    Wind slabs near the ridgeline at Big Creek Saturday

Avalanche Discussion

Today is a stessful day if you are the snowpack, increased snowload on a weak snowpack amplified by the Southwest wind and warmer temps, and possible rain on lower elevation snow may be enough to start an avalanche naturally, or allow you to trigger an avalanche in steep and or wind loaded terrain. Coverage is improving with each snowflake, but never stop looking for clues to avalanche problems and buried obsticles that you may run into....safe and conservative travel decisions are going to be necessary for a successful day in the mountains.