Bollettino valanghe

Blues

Wallowa Avalanche Center
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Pericolo valanghe

Fri
Alta quota
3 · Marcato
Limite del bosco
3 · Marcato
Sotto il limite
3 · Marcato
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In sintesi

Rain on snow yesterday has destabilized the upper snowpack and will take some time to adjust to this change.   It remains possible for a smaller wet-loose avalanche to step down into deeper weak layers in the snowpack, resulting in a larger and more destructive avalanche.   If you are seeing signs of wet loose avalanches, stay off of steep slopes and avoid recreating above terrain traps such as cliffs, gullies, or creeks.  

This forecast is sponsored by Wallowa County Search and Rescue.

Problemi valanghivi

  • Loose Wet

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

    The Milkshakes snotel received 6" of new snow but 1.2" of Snow Water Equivelant yesterday.  This tells us that a rain on snow event likley occured.  Rain on snow can quickly destabilize the upper snowpack and create wet-loose avalanches.  Look for signs of the upper snowpack loosing cohesion such as roller balls or pinwheels.  If you find yourself stepping off your machine or out of your skis/boards and you sink into wet/sloppy snow up to your ankles, you should avoid steep terrain and steer clear of recreating above terrain traps.  

    Evidence of recent wet loose slides

    Photo: Karen Morse

  • Persistent Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Possible
    Dimensione
    2–3

    Forecasters found alarming snowpack structure on the backside of Spout Springs last week.  Large Surface Hoar was found sitting above the January facets, making this snowpack more sensitive than elsewhere in the region.  While the surface hoar may be spotty in distribution, this makes things particularly tricky and demands a rider to dig down to investigate what's below their machine before committing to steep terrain. 

    The most likely place to trigger an avalanche on these weak January facets will be in areas that hold a shallower snowpack with a cohesive slab of snow above the facets. 

    Persistent slabs often resist showing their hand, and may or may not offer obvious signs of instability such as shooting cracks or collapsing of the snowpack.  Continue to use careful terrain and group management techniques: Only expose one person to a slope at a time, keep eyes on, and always regroup well clear of avalanche runouts.  

Avalanche Discussion

What Happened? 

Yesterday brought 5" of new snow to the High Ridge Snotel, and 6" of new snow with 1.2" of Snow Water Equivelent to the MilkShakes snotel- this means rain-on snow.  

What's does it look like....and what is the likelihood? 

It will be likely to trigger a wet loose avalanche in steep terrain today at all elevations in the Blues.  

The persistent slab problem could be sensitive where you could find surface hoar combined with the January facets that sit above a firm layer of snow. 

If you are seeing rollerballs/pinwheels or sinking up to your ankles in wet sloppy snow, retreat to shadier aspects and avoid riding above terrain traps. 

What to do about it? 

Monitor how wet the upper snowpack is.  Test the reactiveness of the saturated snow by ski cutting or riding across small and inconsequential test slopes.  

You will find many long-time professionals in the area still sticking to slopes 30 degrees or less to manage the Persistent Slab problem.  Continue to dig down and investigate the structure of the snowpack.  If you find hard over soft with a firm sliding (bed) surface below, you have all the right ingredients for a slab avalanche.  

Use terrain to your advantage and manage your group well. 

You can't get caught up in an avalanche if you aren't in avalanche terrain.  Evaluate the terrain carefully, and if you decide to engage in avalanche terrain, manage your communication and your partners well.  Only expose one person at a time to avalanche-prone slopes, keep eyes on them, and regroup in areas that are well clear of the runout of an avalanche path.  

It's been great to see all of the recent observations.  Keep 'em coming.  Add value to your forecast.  Submit an observation here.  

 

 

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