Avalanche forecast

Southern Wallowas

Wallowa Avalanche Center
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Avalanche danger

Mon
Alpine
3 · Considerable
Treeline
3 · Considerable
Below
3 · Considerable
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Highlights

An unusually weak upper snowpack exists, and it continues to be stressed by incremental loading of new snow and wind-blown snow.  The most likely places to trigger a large avalanche are in wind-loaded terrain along ridgelines and in sheltered northerly-facing terrain where the new snow has settled into a cohesive slab.  If entering avalanche terrain, utilize a conservative mindset, and carefully evaluate the interface between the old snow and new snow.  

This forecast is sponsored by Outlaw Motor Sports.

Avalanche problems

  • Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    1–2.5

    As the new snow settles into more of a slab and we incrementally load more snow onto a weak upper snowpack, the avalanche problem will transition from a storm slab problem to a persistent slab problem.  The most likely areas to find weak, faceted snow at the old/new interface will be in sheltered northerly facing terrain.   Persistent slabs are notoriously tricky to manage, and often offer little in the way of signs of instability before it's too late.  Our recommendations would be to utilize a conservative approach to entering avalanche terrain as we gain a better handle on the sensitivity of this problem.  There could be a high degree of variability in the old snow surface between adjacent slopes, so careful evaluation will be critical moving forward.  

    The Persistent Slab problem will pose the highest complexity and consequence in the Halfway area of the Southern Wallowas where the greatest snow totals have overloaded the snowpack.

    We are lacking recent observations from this area, so please provide us with your observations if you are traveling in that zone.  

    Storm Slabs ran naturally on Friday night.  We will be transitioning from a Storm slab problem to a persistent slab problem.  

  • Wind Slabs

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

    The most likely place to encounter a reactive wind slab today will be along ridgelines and on cross-loaded mid-slope features where the consolidated and wind-stiffened snow sits on a weak old snow surface.  This is a tricky problem to evaluate because of the variability of the old snow surface.  There could be a high level of variability even among adjacent slopes.  

    Due to the variability of the old snow surface (read the below discussion for more information on this), our usual standby observations may not be relevant to adjacent slopes.  You can dig a hand pit, cut a test slope, or evaluate a snowpit in one location, but it may not necessarily translate to a nearby slope.  This is the setup that can catch even the most seasoned backcountry traveler off guard.   Evaluate each slope carefully before committing to consequential avalanche terrain.  

    Observers in the Western Wallowas yesterday backed off of wind loaded Northerly terrain after observing propagating results in their extended column test (ECTP3).  This was due to a wind slab above weak faceted snow.  

    (12/26/2024) Photo: Caleb Merrill

Avalanche Discussion

A return to active winter weather is here, ending the January dry spell.  Our last measurable snowfall before this was on January 10th.   The extended high pressure brought plenty of sun, wind, and mostly cold temperatures.  These conditions created a variety of conditions on the surface of the snow.   As we introduce a new load to this weak snowpack, it will need time to settle and will take a longer-than usual amount of time to bond to weak old surfaces.  

A storm started impacting our area on Friday morning, with some tricky weather forecasts and high levels of uncertainty about the storm track and associated moisture.   New snow amounts varied throughout our forecast zones.   The Southern Wallowas out of Halfway and the Northern Blues avalanche forecast zones have received enough new snow to raise the alarm bells.  Each of these areas have received between 14-18" of new snow and over 1.5" of Snow Water Equivelant.  It's pretty obvious in these zones that a step back is necessary.   The "tweener" amounts of new snow in the Elkhorns, Western Wallowas, and Northern Wallowas (4-8" with another 2-4" on the way today) make assessing the new snow instabilities a bit trickier.  Obvious signs of instability may not be clear and present, but anywhere there is 6-8" of new consolidated or wind-blown snow on a suspect interface, use caution and consider avoiding avalanche-prone slopes (above 30 degrees.  What are the suspect interfaces you ask?  See below. 

  • On shady and wind-sheltered northerly aspects, the new snow will not bond well to the 10-12" of weak, sugary facets and/or surface hoar.   The new and wind-blown snow may be able to hang in the balance for some time before a trigger is introduced to the equation.  Don't let the trigger be you! 
  • On solar aspects, the new and wind-blown snow will not bond well to firm surfaces that have gone through multiple melt-freeze cycles.   If you find areas where weak sugary snow exists below these crusts, a greater degree of caution should be used.  

As always, be on the lookout for the freebie signs of unstable snow: recent natural avalanches, shooting cracks, and whumphing of the snowpack.   With a developing persistent slab problem, the absence of these clues does not mean that a slope is safe to ride, and  careful evaluation should be used moving forward.   If you don't feel confident navigating these waters, I don't blame you- but the good news is there is plenty of good riding in terrain less than 30 degrees that isn't in the runout of large avalanche paths.  

See below for a video of my observations from yesterday in Angell Basin.  Check out a couple of recent observations from before the storm from WAC staff in the Elkhorns here and here.  

Observations:   Add value to your avalanche forecast.  Help us reduce uncertainty.  This weekend will be an ideal time to submit an observation if you get out in the backcountry.  

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  • Feb 2: Tour with WAC Staff:  Ski tour into Angell Basin to better understand how to safely travel in avalanche terrain.  Please consider purchasing raffle tickets, bidding on an auction item, or donating $50 to the Wallowa Avalanche Center if you are planning to attend this tour.

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