Avalanche forecast

Elkhorns

Wallowa Avalanche Center
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Avalanche danger

Alpine
3 · Considerable
Treeline
2 · Moderate
Below
2 · Moderate
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Out of date — this forecast expired 4 years ago. You’re viewing past conditions, not the current bulletin.

Highlights

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.

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Avalanche problems

  • Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    1–2

    There is a widespread layer of buried surface hoar down 1.5 to 2 feet in the upper snowpack. This 1/18 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. If snow totals over the weekend creep up into the 10-12" range, the weight of the new snow will increase the likelihood of triggering this weak layer.

  • Wind Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    1–1.5

    Moderate westerly winds, 15-20mph and gusting in the 30's 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. Wind slabs reactivity will increase throughout the day as the storm system drops up to 8" new snow in the northern Elkhorns and 3-4" in the northern Wallowas.

  • Deep Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Unlikely
    Size
    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 likelihood of triggering one of these very dangerous avalanches is low but the consequences of doing so would be dire and involve most of the snowpack. 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. It was buried on 1/18. 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. The new snow forecast through Saturday will also add weight and stress to the snowpack heightening the possibility of triggering this nasty beast.

An example of this is a snowmobile triggered avalanche in the southern Wallowas on Tuesday that was 3' deep, 50 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.

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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. If you have some baking skills and want to support the WAC and donate a pie for the auction, please reach out to us via email.
  • 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.  

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