Bollettino valanghe

Central Cascades

Central Oregon Avalanche Center
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Pericolo valanghe

Sun
Alta quota
1 · Debole
Limite del bosco
1 · Debole
Sotto il limite
1 · Debole
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In sintesi

Triggering an avalanche on Saturday will be unlikely. The buried surface hoar that has been mentioned all week has been found on northerly and easterly facing slopes and has not produced any recent avalanche activity. If you are hunting out those obscure, steep, and committing lines in extreme terrain, it is still not a bad idea to dig in and evaluate the snowpack before dropping in.

Problemi valanghivi

  • Persistent Slabs

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

    The persistent slab problem is related to a layer of buried surface hoar. In the last few days no avalanches or signs of unstable snow such as collapses, whumphs, or cracking in the slab have been reported. 

    No propatation was found during snowpack testing on this layer at a variety of test sites. In  most snow pits, the surface hoar crystals have been found to be laying down and beginning to degrade. Although one report from Ball Butte on Friday reported to the buried surface hoar to be more upright on a SE aspect near treeline.

    The weak layer has been found anywhere from 40 - 60 cm (16 - 24") below the surface. It is still out there and pretty easy to find in snow pits. It is too early to take it off the problem list entirely, if for no other reason than to keep in in mind. In rare isolated terrain there is a low likelihood of triggering an avalanche that could be large.

Avalanche Discussion

The overall snowpack condtions will not be much different than they were on Friday. 

In Central Oregon, we do not get many persistent weak layers but it does happen from time to time. December and early January is when we typically see them. With time, they usually become non reactive. Compared to other regions in the mountain west, our persistent weak layers do not persist for long. Also, with time after the last addition of snow, these layers tend to quiet down and become less active. It is possible that when the next big  storm comes through and adds weight to the upper snowpack, this layer could 'wake up' and become active again. 

On Thursday and Friday new surface hoar formation was observed to be widespread near and below treeline. It is not a concern on the surface, only when it becomes buried by new snow. Surface hoar can be destroyed by wind and sun and may or may not stick around long enough to become buried by new snow. We will keep an eye on it between now and when the next round of storm snow comes in. 

 

 

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