Bollettino valanghe

Bollettino valanghe

Payette Avalanche Center
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Pericolo valanghe

Alta quota
3 · Marcato
Limite del bosco
3 · Marcato
Sotto il limite
2 · Moderato
Non aggiornato — questo bollettino è scaduto 4 years ago. Stai vedendo condizioni passate, non il bollettino in corso.

In sintesi

Dangerous avalanche conditions exist. Strong winds and heavy snow along with warm temperatures have likely created sensitive wind slabs in upper elevation exposed and leeward terrain. The recent snowload of around a foot of snow has likely overloaded our persistent weak layer and created a sensitive slab in wind-sheltered areas also. 

Human-triggered avalanches are possible on slopes steeper than 30 degrees. 

Watch for red flags like cracking or whumping sounds in the snowpack. Choose simple, low-angle terrain to travel and play on.

 

Problemi valanghivi

  • Wind Slabs

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

    Avoid wind-loaded terrain...Human-triggered wind slab avalanches are likely. Most winds were strong and out of the Southeast and East. Leeward terrain may be variable as local terrain influence may push the wind in unusual directions. Watch for signs of drifting, etching in the snow, and or the direction in which the cornice lips hang. Stay far back from the edge of the cornice as they can definitely break farther back than you may think...Wind-loaded slopes are going to be dangerous and you may be able to trigger a really big avalanche that could step down into weak layers deeper in the snowpack. 

    North winds will come in tonight and cool things off which may stiffen up these fresh slabs making them more touchy.

    Strong winds at the Granite Weather Station over the last few days!

  • Persistent Slabs

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

    It's possible to trigger an avalanche 3-4 feet deep on buried weak layers that are in the middle of the snowpack and near the ground.  Recent heavy snow may have already overloaded the snowpack or have set up a touchy scenario waiting for a human trigger...Many slopes have variable depths and may have already slid naturally which may make determining the location of this problem difficult. We have seen fairly well-preserved surface hoar crystals and near surface facets in the middle of the snowpack where test results have been hard but have the energy and potential to propagate a fracture in our snowpack that has an overall poor structure. 

Avalanche Discussion

 

 

The likelihood of natural avalanches is winding down but we need to be careful because humans still have the ability to trigger avalanches!

Recent winds and around a foot of heavy snow fell under a warmer period of more than 10 degrees. We will have an upside-down or denser layer near the upper portion of the snowpack. You can count on Avalanche problems like Wind slabs in leeward terrain where the wind has deposited slabs that may be resting on weak snow. Not only are we concerned with wind slabs but this heavy snow will have formed sensitive slabs in wind-sheltered areas also known as storm slabs...Slabby snow overall on top of cold dry snow with faceted persistent weak layers of concern in the middle of the snowpack and near the ground. 

Steep terrain is going to be holding not only slabs but possibly enough loose snow to get you into trouble with sluff or loose snow avalanches. Keep your eyes on your partners. Make sure everyone in your group has a transceiver, probe, and shovel on their person, and knows how to use it. Today is a great day to practice with your beacon (there is a BCA beacon park at the Little Ski Hil) and be conservative in the decisions you make in the mountains...Watch your slope angle and use your slope meter to measure slope steepness---it may surprise you. You can download slope meter apps for your phone in degrees.  Staying off of slopes steeper than 30 degrees may be your best bet. Watch for consequential terrain like gullies or creeks that are referred to as terrain traps where you can be buried deeply.

Careful snowpack evaluation and cautious route-finding are going to be the name of the game as colder clear temps along with the current snowpack may keep some of our buried persistent weak layers as a lingering threat, and grow some fresh facets on the surface this upcoming week as Wednesday and beyond looks to be cold and clear. Snow quality will be good enough to keep people happy. Make sure you have warm layers!

Check out some of our recent observations and or submit one of your own.  We appreciate it!