Bollettino valanghe

Stevens Pass

Northwest Avalanche Center
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Pericolo valanghe

Thu
Alta quota
2 · Moderato
Limite del bosco
2 · Moderato
Sotto il limite
2 · Moderato
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In sintesi

Another round of moist snow is in store for Wednesday. Small storm slabs may become a concern at upper elevations, and loose wet slides could run or be initiated on steep slopes once the new snow becomes wet later in the day. Stay atuned to the surface conditions and signs of instability like shooting cracks or rollerballs- choose your terrain accordingly.

Problemi valanghivi

  • Storm Slabs

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

    At upper elevations where more new, dry snow may fall, check and see how it reacts on steep slopes. Slabs could be more reactive in areas of fresh wind loading, but with warming temperatures we may see an 'upside down' storm layer. You can evaluate how well the new slabs are bonding with simple tests like slope cuts, skin track tests, and hand shears.

    If you find signs of instabilities like shooting cracks or easy failures with tests, than steer away from steep large or consequential slopes. There's a small chance that if you trigger a small slab, it could step down to a deeper slab on older weak layers. Check the East Central forecast if traveling to the eastern edge of this zone. 

     

    Example shallow but fairly wide natural soft slab in Rock Mountain's East Bowl.

    Photo: Matt Primomo

  • Loose Wet

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

    Snow surfaces became wet over the past few days with light rain falling on a previously dry snowpack. By Wednesday morning we should have a new crust, and we expect 3-6" of new snow. This should create a good surface for that new snow to slide on once the daytime warms up a bit. On some slopes the surface crust could melt down, which means slids could grow larger and entrain a significant amount of heavy snow. Wet loose slides could also trigger larger wet slabs in some cases.

    Wet slides often start from trees or rocks shedding snow onto slopes below, but you can also trigger them with your skis or snowmobile. Look for signs of instability that include rollerballs, or fresh wet slides. Identify steep features that warrant caution, and keep checking in to see how conditions are changing throughout the day.

    Example of a small wet loose avalanche. 

    Photo: Matt Primomo

Avalanche Discussion

Temperatures warmed substantially on Tuesday, and the snow reluctantly turned to rain. A widespread wet loose cycle was observed from many areas that started around 10am. These ran in the D1-1.5 range, but a handful were D2's (Lichtenberg), and perhaps one D2.5 (West Camp on S side of Rock Mtn).

Some very large avalanches ran on deeper weak layers within the Solstice Crust sandwich earlier in the month. Regionally, a very large slide was triggered on a similar old crust layer at Crystal Mountain on Tuesday (see photo). This was a large slide that stepped down to become a very large one.  The Solstice crust is now 4-5 feet below the surface in much of the zone. The weak layers consist of faceted melt forms, and some snowpack tests have given sudden and propagating results. If you see evidence of any recent avalanches, please let us know with an observation.

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