Lawinenlagebericht

Northern Wallowas

Wallowa Avalanche Center
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Lawinengefahr

Mon
Hochgebirge
2 · Mässig
Waldgrenze
2 · Mässig
Unterhalb
2 · Mässig
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Kernpunkte

Human-triggered avalanches remain possible, where the wind has formed a slab above weak snow that is now buried 1-2' below the surface.  You can find this dangerous combination anywhere the wind has stiffened the surface snow to create stronger snow sitting on top of weak snow from last week's cold snap.  To avoid triggering a large avalanche avoid riding slopes >35 degrees, don't hang out in run-out zones, and use conservative terrain selection.  

This forecast is sponsored by the Wallowa Country Gamblers snowmobile club in Enterprise, OR.  

Lawinenprobleme

  • Loose Wet

    • Hochgebirge
    • Waldgrenze
    • Unterhalb der Waldgrenze
    Wahrscheinlichkeit
    Likely
    Größe
    1–1.5

    Warm temperatures, significant solar radiation and rising snow levels will turn on the wet loose factory today.  Wet loose avalanches often start out in steep terrain near rocks and trees and fan out as they collect more snow while traveling downhill.  They are good indicators of the surface snow warming and becoming more slab-like.  Avoid steep slopes with wet loose activity, as we know there is weak snow beneath the foot of fresh that fell last Sunday.  

    As daytime temperatures increase look for higher elevation shaded N-E aspects to recreate, or avoid traveling on or under sun-affected slopes >30 degrees.  Consider your route selection later in the day or as you are exiting the field, as you don't want to get caught traveling on or below steep terrain that has been getting a lot of sun.  

  • Persistent Slabs

    • Hochgebirge
    • Waldgrenze
    • Unterhalb der Waldgrenze
    Wahrscheinlichkeit
    Possible
    Größe
    1–2

    The What: Last week's cold snap produced two persistent weak layers, that are now buried 1-2' below the snow surface.  Weak facets and surface hoar were observed yesterday in two snowpits, one at 8,000' (West Aspect) and the second a 6,000' (West Aspect).   In locations where a more cohesive slab has formed above these weak snow grains, we've seen numerous human-triggered avalanches this week.  They have been on a variety of aspects above 7,000'.  All of these slides have been remote triggered from low-angle terrain!

    The Where: You can find weak snow on nearly all elevations and aspects buried below the storm that rolled through last Sunday, which produced 1-2' of snow.  Last weeks frigid temperatures created weak snow at the surface which we call near-surface facets, and surface hoar.  This weak snow has been reactive in areas where a slab has formed above it.  

    What to do: Surface hoar and facets don't disappear overnight, that's why we call them a persistent weak layer.  You may feel whumping or collapsing or observe shooting cracks, but not always.  If you truly want to know what's beneath you, get out your shovel and do some digging.  If you find strong snow, over weak snow you have a slab.  Stick to lower-angle terrain, increase your margins, and ski and ride one at a time in steep terrain.  

    So What: Yesterday while out riding in the East Fork of the Pine, I observed snowmobile tracks on steep slopes, with numerous trigger points.  So how come these folks didn't trigger an avalanche, and why should I take your advice you might ask?  The reality is, the snowpack is incredibly forgiving, most of the time, even when the snowpack structure is poor.  But, when the structure is poor, I reduce my personal risk threshold, because all I have to do is find the sweet spot, and that might make the difference in whether I get to come home safe at the end of the day.  

     

    (2/9/2023)

    Photo of a remotely triggered persistent slab avalanche in the Southern Wallowas. This avalanche occurred on a northeast-facing slope at 7850'.  Avalanche occurred on Thursday.

Avalanche Discussion

Another day of warm temperatures in the Southern Wallowas will increase the chances of triggering a Wet Loose avalanche or a Persistent Slab.  If you feel the snow getting warm and mushy, it's time to look for higher-elevation, shadier terrain.  A wet loose avalanche could push you into consequential terrain.  Pinwheels and roller balls are good indicators that the surface snow is heating up.  

Thanks to everyone who participated in this year's Halfway Backcountry Ride and fundraiser yesterday.  Funds raised will benefit not only the Wallowa Avalanche Center but also two local Halfway families who recently lost loved ones in motor vehicle accidents.  We can't thank everyone enough for putting on this incredible event.  

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