Bollettino valanghe

Blues

Wallowa Avalanche Center
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Pericolo valanghe

Sat
Alta quota
2 · Moderato
Limite del bosco
2 · Moderato
Sotto il limite
1 · Debole
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The warm temperatures and direct sun will create wet snow avalanches in steep terrain.  If you start to see roller balls and pinwheels, point releases from rocks or vegetation, or you are sinking up to your boot tops in wet slushy snow, it is time to change your aspect and elevation.  Given the warm temps over the past few days, there is a chance of triggering a wet slab avalanche on east through west aspects.  Avoid traveling on or underneath steep, cliffy terrain that is getting direct sun. Also, steer clear of cornices during this warming event.  

The forecast presented by @onxbackcountry. onX Backcountry is a GPS navigation and mapping tool designed with your backcountry objectives in mind, equipped with Avalanche Forecast and Slope Angle layers, Offline Maps and more.

Problemi valanghivi

  • Loose Wet

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

    Yesterday we observed several natural wet loose avalanches above and near treeline on all aspects.  Rollerballs and pinwheels have also been observed in many locations indicating that the surface snow is warming and losing strength.    Wet loose avalanches start out in steep terrain, often around rocks and trees.  They can be dangerous when they start accelerating down the slope and increase in mass, especially when sliding on an old crust layer.  If you see signs of rollerballs and pinwheels, point releases out of steep rock areas, or you are sinking up to the top of your boots in wet loose snow it is time for you to get off those slopes and find lower angle terrain.  Avoid traveling underneath or on steep confined or cliffy terrain.

    (3/24/2022)

    Example of a Wet Loose avalanche yesterday in the Western Wallowas on north-facing terrain.

    Photo: Victor McNeil

  • Wet Slabs

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

    Warmer than average temperatures over the past few days have resulted in the upper snowpack becoming saturated.   As the surface snow continues to melt, water is percolating into the snowpack and pooling on one of the many crust layers we currently have in our snowpack.  Once this "slushy" meltwater pools and spreads along with the layer it weakens the bond between the overlying slab and the crust.   Wet slab avalanches can be large and destructive and are very difficult to predict.   We currently have plenty of old crusts buried in our snowpack, and with no overnight freeze, the opportunity for wet slab activity is possible.  We could also see wet loose avalanches start and turn into a wet slab.  

    To avoid this avalanche problem, stick to lower angle slopes as the surface becomes sun-drenched, and don't travel on large and steep open slopes later in the day. Avoid steep, confined or cliffy terrain as temperatures remain warm and freezing levels are above 8000'.  Timing and slope angle are key today when traveling.

    This picture is an example of water percolating down through the snowpack and sitting on a crust.  If this is observed in the snowpack there is potential for wet slab avalanches 

    Photo: Kelly McNeil

Avalanche Discussion

Again today we will be experiencing some of the warmest temperatures of the season.   The highs are forecasted to be in the mid to high 40s today in the Elkhorns and Wallowas and 50s in the Blues.  In addition, many locations in the mountains have not seen freezing temperatures overnight resulting in a warming of the snowpack and increasing the likelihood of triggering wet loose and wet slab avalanches.  As the slopes receive sun and the snow becomes saturated, you do not want to be traveling on or underneath steep terrain. 

These warm temperatures are transitioning our winter snowpack into a spring snowpack rather abruptly.  The change happens every year and sometimes quicker than others.  We need to give the snowpack time to go through this process.  When we are experiencing quick warmups and many nights without overnight freezes the snowpack can become active on the old crust and weak layers that have not been reactive thus far.  As mentioned in yesterday's forecast, a layer of buried surface hoar was reactive in the snowpack test during the weekend of March 12th (observation).  It is important to keep your eyes open to new problems and old problems that have been dormant in the snowpack.  

With the many melt-freeze, rain, and sun crusts we have in our snowpack, coupled with water percolating down, the snowpack structure is weakening, and we have a recipe for wet slab avalanches.  The timing of a wet slab is nearly impossible to predict, so avoidance is the key.  If you are sinking to your boot tops in wet snow it's time to change aspect, slope angle, or Go Home!  You don't want to travel on or under sun-drenched slopes.  

Cornices could also be an issue in the next few days and should be given a wide berth.  As they warm up they could start to sag and fail.  

Please send us your photos and observations or use the hashtag #wallowaavalanchecenter on social media.  

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