Lawinenlagebericht

Silver Valley & Bitterroot Mountains

Idaho Panhandle Avalanche Center
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Lawinengefahr

Sat
Hochgebirge
2 · Mässig
Waldgrenze
2 · Mässig
Unterhalb
2 · Mässig
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Veraltet — dieser Lagebericht ist 5 years ago abgelaufen. Du siehst vergangene Verhältnisse, nicht den aktuellen Bericht.

Kernpunkte

With no freezing temperatures predicted for the next several nights, the snow is going to get a little sloppy. Wet snow avalanches will become likely on or below steep slopes that receive lots of sunshine.  If you are sinking over your boot tops, setting off rollerballs easily that gather speed and snow as they go downhill, and are stripped down to just a t-shirt, then it's time to get out of avalanche terrain.  Keep your eyes peeled above you, the cornices are starting to sag.  Definitely don't want to be in the way of one of those dropping!

 

Lawinenprobleme

  • Loose Wet

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

    The weather is predicted to be warm at the highest elevations for today and tomorrow without going below freezing during the night.  This means the snowpack will already start the day without that frozen bridge on top and become unstable that much earlier.  We preach rollerballs and there is a reason for that!  Watch how they form throughout the morning and when they start fanning out from your skis (sled or human), it's time to get out.   Pick terrain where you can escape to low angle slopes that aren't threatened from above.

    Large skier triggered pinwheel.

  • Wet Slabs

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

    Unlike dry slab avalanches, you don't have any indication of the likelihood of a wet slab avalanche from doing a pit test.  You can do a pit that shows the snow is stable and doesn't move an inch; half an hour later it hits that magic temperature threshold and a slide happens.  Wet slabs are unpredictable that way.  Fortunately, they are easy to mitigate! Get out when you start seeing those signs of wet snow instability.  Rollerballs that are growing and fanning out and unsupportive snow (sinking when you step in it).

    Small wet slab triggered on a convex rollover.

  • Cornices

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

    The cornices are starting to get a little droopy.  Nope, that's not a technical term, but you know what I'm trying to illustrate.  Cornices may collapse abruptly, and you don't want to be underneath or on top of them! They drop large, hard, dense debris that can run a long ways down a steep slope.   Not something that you want to tangle with!  If you are travelling on the ridges, pick a line that is on the windward side to keep you from being too close to where a cornice could break. They usually break back farther than you think.

Avalanche Discussion

It's spring! So why isn't the avalanche danger low?  There are several factors that are working together to increase the wet snow avalanche danger for the next couple of days.  A warming trend over the last couple days and extending forward (check the weather tab), a mashed potato snow surface that is a few days old, no overnight refreeze of the snow surface to form a bridge, that brown dust layer that came in, and sunny skies.  The snowpack is already starting out warm (not frozen) this morning and will only continue to warm throughout the day with solar radiation.  The brown dust layer we got on Monday isn't going to help matters.  Think of standing outside in a white t-shirt vs a black t-shirt.  It isn't that drastic, but in terms of snow stability it is enough to make a difference.  It's going to be easy to trigger loose-wet slides, especially where nobody has ridden since the new snow on Monday.  And those ice layers underneath make ski cutting a wet slab a possibility.  Yesterday we were able to see several cornice bombs on far off ridges as well.  

The fourth problem to mention is glide avalanches.  These go hand in hand with spring around here.  A lot of our usual players have opened up by now, make sure to stay out from under open glide cracks.  They can become full wet slides during these temperatures.  

This is my last forecast for the season. Thanks everyone for a great season!  Appreciate all the observations, they've helped round out the forecasts for the Silver Valley.  Skiing and riding isn't over yet, so I might still see you out there!

 

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