Bollettino valanghe

Blues

Wallowa Avalanche Center
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Alta quota
2 · Moderato
Limite del bosco
2 · Moderato
Sotto il limite
Senza grado
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As cloud cover decreases today, small wet loose avalanches will be likely within the new snow on sunny slopes steeper than 35 degrees.  Recent winds have transported snow into pockets of dense slabs that may be reactive on leeward aspects along exposed ridgelines.  Be suspicious of pillowed textured snow that can be found below corniced ridgelines.  Avoid steep sunny slopes when the sun is warming the snow surface to a mushy mess.  

This forecast is sponsored by Wallowa County Gamblers Snowmobile Club.

Problemi valanghivi

  • Loose Wet

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Likely
    Dimensione
    1–1.5

    This time of year it does not take much for the sun to take control of warming new snow on the surface.  As cloud breaks reveal sunshine, expect to see roller balls and natural wet loose avalanches within the new snow.  Look for these to start to release from rocky areas and below cliff bands.  As the day progresses if the sun is shining, look for signs of warming snow such as roller balls releasing from your turns.  Avoid slopes steeper than 35 degrees on any aspect catching direct sun if you are encountering wet snow below your feet or machine.   They may stay small today, but don't underestimate their ability to knock you off your feet and carry you over a cliff or push you into a gully.   The 1-2' of recent storm snow sits above a crust that formed early last week and will be an ideal sliding surface for any new wet loose avalanches.  At lower elevations,  wet snow surrounds this crust and hasn't completely frozen in the last several days.  A wet loose avalanche in isolated steep areas at lower elevations has the potential to entrain this older wet snow.  

    Small wet loose avalanches naturally releasing from rocky areas. (3/22/2024) 

    Photo: Caleb Merrill

  • Wind Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Possible
    Dimensione
    1–1.5

    Wind slabs will linger along exposed ridgelines and could be sensitive to the weight of a rider.  Since the most recent storm started on Wednesday, winds have blown out of the South initially before turning to the North and Northwest.  This has left several "generations" of small wind slabs on a variety of aspects along exposed ridgelines.  The older wind slabs- mostly on Northerly aspects have had time to relax, but will be covered by new snow and may be harder to identify.  Newer wind slabs will likely be on East and South aspects, will be easier to identify by looking for a textured or wavy appearance on pillows of drifted snow, and will likely be below corniced ridgelines. 

    I traveled near the treeline yesterday in the Northern Wallowas and saw evidence of wind loading from the NW winds, but I did not find any reactive wind slabs on small test slopes below corniced ridgelines.  The most likely place to find a reactive wind slab will be at upper elevation exposed ridgelines.  Use small test slopes that are representative of what you may be looking to ride to test the reactivity of wind-loaded slopes.  If you can break off slabs of stiffened snow, are getting cracking around your boards or machine, then you've found reactive wind slabs.  While they may be small and mostly manageable, don't let a wind slab carry you over consequential terrain or into a terrain trap.  

     

    (2/20/2024)

    Wind Slab development. 

    Photo: Caleb Merrill

Avalanche Discussion

Springtime brings wildly dynamic weather to the mountains.  If you don't like the weather, just wait a few minutes and you may just get what you are looking for.   A storm that started warm and rainy on Wednesday turned colder and brought 1-2' of snow to the mountains.  Periodic snow showers have added to storm totals, but have been spread out over the last 4 days and seem to be mostly well bonded to the old snow surface.

The new snow fell onto a melt-freeze crust from earlier in the week.  Throughout your travels today, dig periodic quick hand pits to see how well the snow has bonded to the older crust surface.  In my snowpit yesterday in the Northern Wallowas at 7800' on a NW aspect, I found large graupel snow sitting just above the melt-freeze crust that was buried on Wednesday night.  Keep an eye on this.  In your travels,  get curious and investigate if the new snow slides as a slab on this layer.  If you are finding that it does, consider dialing back your terrain selection.  

Occasional breaks in the clouds have given observers brief glimpses into the alpine, but I would say observations are still limited above treeline  As of Sunday morning, I have not seen or heard about any natural or human-triggered avalanches in the region.  

In addition to wind slabs and wet loose avalanches, be on the lookout for some dry loose "sluffs" in wind-sheltered terrain on shady aspects.  Expect these to remain small and manageable, but don't let them knock you off your feet and carry you over consequential terrain.  

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We will continue to mention deeply buried weak layers that are in the form of weak snow around the 2/1 crust, now buried 4-6 feet deep under dense slabs of snow.  It has become very unlikely that this weak layer will be reactive to the weight of a rider, but not altogether impossible.  The needle in the haystack scenario would include riding on steep rocky convexities where the snowpack is shallow.  Investigate what's under your feet and consider the consequences of your decisions.  

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New snow at the lowest elevation band in the Blues (3000-4000') has fallen on bare ground.  While the new snow will not create avalanche issues at this elevation, a significant hazard will be in the form of shallow-covered obstacles.  

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Today will be the last scheduled full avalanche forecast providing a danger rating.  A general avalanche information bulletin will be written tomorrow and will be updated as conditions warrant throughout the rest of the spring season.  We hope to see your observations continue to add valuable information to help keep everyone safe in the mountains.  Please submit your observations here.   A heartfelt thank you to our community who have supported the Wallowa Avalanche Center with financial contributions, submitted valuable observations, taken part in avalanche education, and perhaps most importantly- supported us all through a very difficult last month.  

 

 

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