Bollettino valanghe

Silver Valley & Bitterroot Mountains

Idaho Panhandle Avalanche Center
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Pericolo valanghe

Sat
Alta quota
3 · Marcato
Limite del bosco
3 · Marcato
Sotto il limite
2 · Moderato
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Non aggiornato — questo bollettino è scaduto 6 years ago. Stai vedendo condizioni passate, non il bollettino in corso.

In sintesi

The snowpack is still adjusting and settling after the big storms earlier this week.  Expect to find small wind slabs and storm slabs still lingering. The more consequential problem that is hidden from sight is the buried persistent weak layer.  This is still proving to be reactive in pit tests and will create big avalanches if it is triggered. 

Problemi valanghivi

  • Persistent Slabs

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

    The hidden dragon, which isn't in a deep slumber yet!  Back in mid-December we had some rainstorms that created several crusts (as many as 4 in some locations!) in our snowpack.  These have faceting associated with them.  The crust/facet sandwich configurations vary by elevation and aspect, but I haven't travelled anywhere that I haven't found some combination of them yet. These became more reactive with the quick, heavy loading that was placed on them earlier in the week and are buried between 2 and 3.5 feet below the surface now.  Check your location, give them a whack, and go into your investigations expecting not to be able to trust them.  This is a problem that is going to be slow to heal. 

    Pit results from 1/7/2021

  • Wind Slabs

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

    There was light snow throughout the day yesterday with enough wind to transport it. Expect to find small, soft wind slabs in the usual starting zones near ridges and ridgelines.  Look for chalky textured snow that sounds hollow when you travel across it.  While these may be thin and easily manageable on their own, if they step down and trigger an avalanche on our persistent weak layer it will be of much higher consequence. 

  • Storm Slabs

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

    The upper storm layers are starting to settle and bond, but it is still possible to trigger small storm slabs in the upper pack.  We have a stretch of calm weather, so these should settle out nicely in the next day or so.  Yesterday we were able to trigger these with ski cuts on small features with a little bit of effort.  Once again, their size alone isn't the big problem, it is the probability of stepping down and triggering an avalanche on the buried persistent weak layer and causing a much larger avalanche. 

    Testing storm slabs in small consequence terrain.

Avalanche Discussion

Patience.  That is what our snowpack is demanding from us right now.  I've started to find that the December rain crust layers are beginning to break down and the facets are starting to round, but this isn't a fast process. This problem will continue to linger buried in the snowpack; getting harder and harder to trigger as time goes on.  But if triggered, they will be very large avalanches.  We traveled to two different locations yesterday, over 3 miles apart as the crow flies and found propagation in our pit tests at both sites.  Other observations have confirmed that this is widespread across our forecast area right now. The storm snow above is still not consolidated, most places we were sinking hip deep into the snow when stood with just boots on our feet.  This puts you weight and force much closer to that buried persistent weak layer.  Go into this weekend not expecting to trust this layer.  Overcome the human factor and consider all negative feedback the snowpack is giving you and listen to it! There is nothing wrong with sticking to low angle riding or sliding. In fact, yesterday it was downright awesome!

We still have an observation contest going on for the month of January.  I love seeing observations by lots of new folks. Keep them coming. 

Check out the following video for conditions from yesterday.  If you want more info on propagation saw tests, check out this good blog by G3.

Regioni coperte