Bollettino valanghe

Southern Wallowas

Wallowa Avalanche Center
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Pericolo valanghe

Fri
Alta quota
2 · Moderato
Limite del bosco
1 · Debole
Sotto il limite
1 · Debole
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Non aggiornato — questo bollettino è scaduto 5 years ago. Stai vedendo condizioni passate, non il bollettino in corso.

In sintesi

Lingering windslabs still exist along ridgelines, and although they are quite stubborn, areas that have seen windloading should be avoided.  Low danger doesn't mean no danger. Small wet loose avalanches are possible below treeline today.  If you are seeing signs of wet loose snow such as point releases, pinwheels, or a wet snow surface- avoid terrain steeper than 35 degrees especially where it may be above a terrain trap such as a cliff, gully, or trees.   

Problemi valanghivi

  • Wind Slabs

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

    The last few days there has been little in the way of snow available for wind transport.  However, there is still evidence of previous wind loading along leeward ridgelines.  These windslabs have had a few days to relax in their sensitivity.  That being said, avoidance of these wind loaded start zones is still recommended.   Look for clues to wind slabs such as rippled snow surfaces or smooth pillowy slabs of snow on the downwind or leeward side of ridgelines.  Cornices also exist in these zones, and may break further back than you expect.  Give cornices a wide berth, and approach ridgelines at an area where you are certain there is no overhanging cornice.  

    (1/12/2022) null Photo: Alonso Mendoza

  • Loose Wet

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

    Overnight temperatures at most stations throughout the zone remained above freezing.  The average overnight temperature on Mt. Howard was 42 degrees.   Small wet loose avalanches will be possible throughout the day at mid and lower elevations, especially if the expected precipitation falls as rain or wet snow in those areas.  Wet Loose avalanches can start as a small point release from a trigger such as a snow falling off a tree, an animal running through a steep rocky area, or a rider cutting across a steep rollover.  (see photo from last week's warmup).  They generally fan out and entrain chunks of wet snow.  While they move slower than dry avalanches, they can easily push a rider into consequential terrain.  If seeing signs of wet loose avalanches such as a wet snow surface, pinwheels, or point releases avoid terrain steeper than 35 degrees above terrain traps.  As temperatures cool throughout the afternoon, the chances of wet loose avalanches will decresase. 

    (1/5/2022)

    This photo was taken during the warmup last week.  Surface snow is warm and wet at this location, has started a point release given the steep slope angle.  Point releases and pinwheels are telltale signs of wet loose avalanche activity. 

    Photo: cm

Avalanche Discussion

Observers report that a warm day yesterday made for snow sticking on skins, and snow dripping off of trees.  The wind cooled things a bit, but mostly just blew around more tree debris.  Terrain that has westerly or southerly aspects are sun and wind affected- a rugged surface in many places.   Reports are that the warmup and rain event from last week brought a rain line to about 5200'.   During the early part of this week, there were reports of quality riding conditions in protected northerly facing terrain.  The warm temps yesterday and last night may have changed that.  As noted above, there are still lingering windslabs in the alpine.  See photo below of a large natural windslab avalanche from earlier this week.  

A mostly right side up snowpack exists in the Northern Wallowas.  Observers on an East aspect at 8200' noted some graupel about a foot down from the surface with a hardness change in the snowpack.  Moderate shovel shear tests were noted on this layer.  

Please submit your observations to the WAC from your travels in the mountains.  There is no observation too small.  We have a large foreast area and limited resources, so even just a photo gives forecasters a lot of information and helps paint a better picture in areas where we  may not have been in awhile.  Keep 'em coming! 

 

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