Boletín de aludes

Silver Valley & Bitterroot Mountains

Idaho Panhandle Avalanche Center
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Peligro de aludes

Sat
Alta montaña
2 · Moderado
Límite del bosque
2 · Moderado
Bajo el límite
1 · Débil
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Desactualizado: este boletín caducó 6 years ago. Estás viendo condiciones pasadas, no el boletín vigente.

Lo esencial

Happy New Year! Expect to find soft wind slabs as you are out and about traveling in the backcountry today. They will continue to build through the weekend as the next storm system starts hitting us tonight and into Saturday with intensified winds.  Small storm slabs will continue to build as well.  I don't expect the danger to change too much for Saturday, but expect the danger to rise on Sunday as we get a lot of heavy, dense snow on Saturday night.  

Problemas de aludes

  • Wind Slabs

    • Alta montaña
    • Límite del bosque
    • Bajo el límite del bosque
    Probabilidad
    Possible
    Tamaño
    1–2

    We had varied winds across the forecast region yesterday and last night, but they were strong enough to build shallow wind slabs on our leeward ridges.  These will grow this weekend, especially starting tonight as the winds pick up with the next storm system moving through.  Watch for hollow sounding snow, that's pillow shaped and chalky in color.  These were soft and easy to mitigate on Thursday but will become more stiff and thicker as the weekend progresses. 

  • Storm Slabs

    • Alta montaña
    • Límite del bosque
    • Bajo el límite del bosque
    Probabilidad
    Possible
    Tamaño
    1–2

    Wednesday and Thursday's storm has already started to settle out but be wary of new storm slabs forming throughout the weekend.  Watch for convex rollovers where these will be most reactive.  Currently they are thin and easy to manage, but they will grow in size as we get more snow.  Sunday's slabs could have quite bit of energy and sliding power with them.  

  • Persistent Slabs

    • Alta montaña
    • Límite del bosque
    • Bajo el límite del bosque
    Probabilidad
    Unlikely
    Tamaño
    2–3

    New Year, same problem.  The buried persistent weak layers are slowly gaining stability, but they still need to be mentioned.  The closest ones to the surface are facets about a foot down in the snowpack and located above, below, or sandwiched in between the December ice crusts.  Isolated sheltered locations have buried surface hoar located above this as well.  Dig down and check your location to see if any of these bad guys are located there.  Look for gray lines in the snowpack and weak sugary crystals.  If you have movement on stability tests, dial back your terrain choices.   

Avalanche Discussion

Well, we made it to 2021 and it looks like it is coming in with gusto!  When we were out in the field on New Year's Eve our main intent was to check the persistent weak layers.  These still vary in location, but pretty much all locations seem to at least have facets associated with the December rain crusts.  There are still buried surface hoar layers fairly widespread located below this, but still within 3ft of the surface and isolated sheltered aspects have buried surface hoar layers above the crust as well.  What I'm trying to say is that we don't have a great handle on where exactly these are all located because they vary from location to location, even if that's only a 100ft away from where you are.  It's best to assume they are there until proven otherwise.  Where we did find them yesterday, we were not finding movement but other observations from the region did have reactivity.  The dormant ones continue to worry me as we get quick, heavy loading on Saturday night into Sunday.  Weather models are saying that we could get enough snow to add over an inch of water to the snowpack!  This is a lot of weigh quickly and snowpacks don't adjust well to that!  Don't let good stability on Friday and Saturday lure you into a false confidence for Sunday.  If a storm slab is triggered on Sunday, it is likely that it will step down through the pack causing a much bigger avalanche.  

We are holding an observations contest for the month of January. Check out the event page to get all the details. I look forward to seeing more observations from the Silver Valley, don't let me down folks! 

Here is yesterday's video. 

 

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