Bollettino valanghe

Elkhorns

Wallowa Avalanche Center
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Pericolo valanghe

Fri
Alta quota
2 · Moderato
Limite del bosco
2 · Moderato
Sotto il limite
2 · Moderato
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In sintesi

Triggering a slab avalanche 1.5 to 2 feet thick is possible on some slopes. Avalanches are more likely on E-N aspects on sheltered terrain below ridgeline. Recent winds have formed reactive wind slabs on N-E aspects in the alpine.

This forecast is sponsored by Magic Woodland Studio.  

Problemi valanghivi

  • Persistent Slabs

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

    There is a widespread layer of buried surface hoar down 1.5 to 2 feet in the upper snowpack. This layer is reactive and capable of producing large avalanches. Carefully evaluate mid-elevation N-E aspects on more protected and shady slopes for this layer. The most effective evaluation method is utilizing snowpack tests like the compression test (CT) and extended column test (ECT). If you get clean planar fractures on a thin weak layer, then you've likey found the buried surface hoar. If you have any uncertainty in regards to the presence of a buried surface hoar layer, then increase your margin of safety by staying off and out from underneath slopes steeper than 30 degrees.

  • Wind Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Possible
    Dimensione
    1–1.5

    Recent moderate westerly winds at ridgetop have moved snow onto leeward terrain features at and near ridgeline. These pockets of hard drifted snow may be reactive to the weight of a rider. Wind slabs could be over a foot thick in places. An additional consideration is a wind slab triggered in the upper snowpack could step down to a persistent weak layer, like buried surface hoar, and produce a large destructive avalanche. Carefully evaluate N-E aspects in the alpine for reactive wind slab and buried surface hoar layers before committing to a slope.

  • Deep Persistent Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Unlikely
    Dimensione
    1–3

    We are still seeing poor snowpack structure in our snowpack in the form of basal facets and crust facet combinations near the ground. These deeply buried persistent grain types are still failing in snowpit stability tests so the deep persistent problem is still on the table. The likely hood of triggering one of these very dangerous avalanches is low but the consequences of doing so would be dire. A deep persistent avalanche can be triggered on steep slope terrain where the snowpack is thin and rocky. The best way to manage the risk is to stay off of and out from under slopes steeper than 30-35 degrees, especially near shallow rocky areas.

Avalanche Discussion

We are in a tricky spot related to avalanche hazard right now. Throughout the ranges of northeast Oregon we have several widespread layers of buried surface hoar. The most reactive layer of buried surface hoar is down 1.5 to 2 feet in the snowpack. Buried surface hoar is a notorious persistent weak layer and has the added hazard of propagating fractures over large distances. What is tricky about surface hoar is that it isn't consistent across the snowscape. It largely lurks on more shaded and protected slopes. The likely place to find buried surface hoar is on E-N mid-elevation slopes below the ridgeline. Another tricky thing about surface hoar is that it is hard to see in the snowpack when digging a pit. The best way to test the upper snowpack for the presence of surface hoar is to do snowpack tests like the compression test (CT) and extended column test (ECT). If you get clean planar fractures on a thin weak layer, then you've likely found the buried surface hoar.

This doesn't mean surface hoar may not exist in the alpine or on more sunny slopes. That is what makes it tricky too. We are in a period right now where careful terrain evaluation and selection is needed to avoid the possibility of triggering a large and destructive avalanche. It is possible to trigger the surface hoar layer in the upper snowpack and have the avalanche step down into weaker layers in the lower snowpack. There are other buried weak layers deeper in the snowpack. An example of this is a snowmobile triggered avalanche in the southern Wallowas yesterday that was 3' deep, 70 yards wide, and ran over a 100 yards. This slide was big enough to bury, injure, or kill a rider. If you are going into terrain steeper than 30 degrees, then you need to carefully evaluate the slope for buried surface hoar. And, if you don't know, then don't go. Keep your slope angles below 30 degrees to be extra safe.

The 11 Annual Eastern Oregon Backcountry Festival is coming up.  Join us for our biggest fundraiser of the year February 3-5th. 

  • Friday, Feb 3rd: HQ in La Grande we are showing "Buried" the 1982 Alpine Meadows Avalanche.  Doors Open @ 5:30, Pie Auction 6:30, Movie starts at 7! Tickets are $5 at the door.
  • Saturday, Feb 4th: Kip Rand Memorial Race registerhere.  Winners will receive $100 cash or an Anthony Lakes season pass for 23/24.  Mens and womens division.   (You must show up 15 minutes before the race starts at the EOBF tent near the rental shop. )
  • Snow safety clinics 10 AM Avalanche Companion Rescue Clinic.  Register here.  
  • 1 PM Snowpack Observation Clinic.Register here.  Space is limited, reserve your spot.  (You must show up 15 minutes before the clinics start at the EOBF tent near the rental shop. ) 
  • Bag of Hammers 3 PM at the Star Bottle Saloon.  Live auction and raffle.  
  • On Sunday you can join the forecasters for a tour into Angel Basin.  Register Here.  

If you aren't able to make it out for the events you can support the WAC by purchasing raffle tickets or bidding on items in our online auctionhere.  The online auction and raffle will run from Jan 20th at Midnight to February 5th at 8PM.  

Regioni coperte