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 buried persistent weak layer is still lying in wait below the surface for an unsuspecting trigger.  In most locations it is 1 to 3 ft below the surface, just above the January ice crust.  Use caution, a human triggered avalanche is still likely in steep terrain.  With light new snow and moderate winds out of the W-SW last night, expect to find wind slabs on the N-NE today.  These will continue to form as the new, light density snow gets pushed around with winds throughout the day. 

Problemi valanghivi

  • Persistent Slabs

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

    Broken record here, which seems to be the case this winter!  The buried surface hoar and facets associated with the 1/12 rain crust will still continue to take a while to stabilize.  These layers are now buried 1 to 3 ft deep in the pack.  They are easy to look for and test, dig a pit down until you've passed the crust, they will be sitting right on top or an inch or two above the crust.  A word  of caution on pits, this problem has been reactive for so long now, that in a lot of mellow locations (ie: locations where people have traveled the last two weekends) this layer has been collapsed and you might get a false stable reading in your pit test.  But the avalanche terrain that you step into could have it still buried alive and well, just waiting for a trigger.    Heads up for whuumphing and collapsing, these are red flags that the area you are traveling through still has a buried persistent weak layer that is ready to bite.  

    (2/18/2021) Pit results from 2/18/2021

  • Wind Slabs

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

    The cold temperatures have provided us with some cold smoke powder.  The lower density of this snow makes it easy to push around. Moderate winds in the night created wind slabs back in our usual places.  Watch for chalky, pillowy snow on the ridge lines on the northern aspects.  Heads up for cross loaded gullies.  Expect these to get thicker as the day goes along. 

Avalanche Discussion

The good news: the snow conditions for riding and sliding are great.  Cold, low density powder makes faceshots and carving really fun.  With small storms coming in waves throughout the weekend, we should be getting some refills to keep it fresh.

The bad news: I still don't trust the buried persistent weak layer enough to step out into avalanche terrain.  What I mentioned about pit tests and false stability ratings is a very scary possibility. I already know of several people that this happened to. Luckily, everyone was okay at the outcome of the slides they triggered.  Where we traveled yesterday we were getting clean, fast propagation from taps from the wrist or elbow on our ECT tests, but I was in an area I know no one had skied near.  It was  a different story when trying to find a spot in travelled corridors. This problem will require patience to wait it out.  I know we are all itching to ride or slide some steeper terrain, especially in such great snow conditions, but give it a little more time. 

Don't forget the observation contest we are having, details are here.  Thank you to those that have submitted observations, especially in the Silver Valley.  Keep letting me know where you are getting propagation!

There will also be an online Q&A session on March 2nd and a raffle from the Friends group.  More details will be posted on the web soon, but mark you calendars for the evening of March 2nd.  If you have any questions you want answered, send them [email protected]

 

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