Bollettino valanghe

Olympics

Northwest Avalanche Center
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Pericolo valanghe

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

An approaching storm will raise the avalanche danger to moderate in exposed high-elevation terrain where you can trigger a small slab on a steep slope. Expect dry loose activity to continue on very steep slopes that haven't seen much sunshine. The SE Olympics continue to receive significantly more snow than Hurricane Ridge and can expect a full notch higher than forecast avalanche danger.

Problemi valanghivi

  • Wind Slabs

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

    The day may start with low avalanche danger at all elevations, but southerly winds and an increase in snowfall by the afternoon will build slabs you can trigger. These winds may strip any new snow above sun crusts on sun-affected aspects, generally loading colder, polar aspects in the immediate lee of ridgelines. Snow surfaces could weaken with clearing Saturday night, so the any wind slabs may be touchy atop the old snow interface. As you move into wind-affected terrain, note the change in snow structure that leads to more challenging trail breaking or a firm over punchy surface layer. Active snow transport or fresh sharp cornices can help you determine which sides of the ridges are receiving wind loading.  Steer around wind-loaded slopes 35 degrees and steeper in above treeline terrain and prepare for dry loose avalanches to move with you on slopes approaching or exceeding 40 degrees.

     

     

     

    Example: Blowing snow can tell you a lot about which slopes are loading up. 

    Photo: Andy Harrington

Avalanche Discussion

Avalanche danger may be significantly higher than forecast for the SE Olympics which continues to be favored with more snowfall in this weather pattern. Another storm arriving Sunday afternoon may bring 2-6" of snow to this part of the range by the end of the day.

Weather and avalanche activity have been quiet in the northern Olympics this week with 2-4" of snow trickling in since Friday morning and we're expecting 1-2" more by the end of the day Sunday. Plan for increasing avalanche danger at upper elevations and decreasing visibility. On Saturday, observers got into alpine terrain for the first time this week and observed minimal slab hazard with small natural dry loose activity on steep slopes. The snow on shaded aspects was right-side-up and settling nicely. On Friday, observers found some slightly poorer bonding where recent snow overlies a sun crust on SW-S-SE aspects. Isolated 6" pockets of slab were found in the immediate lee of ridgelines below fresh cornices. Near and below treeline any avalanches occurring on the 3/10 interface will be very shallow and very small. If you do see more signs of wind-affected snow near treeline by Saturday, assume there has been more wind than forecast and that reactive slabs could extend into near treeline terrain. We don't have current layers of concern deeper in the snowpack. Remain vigilant and reduce exposure to corniced ridgelines such as the one pictured. Snow coverage is currently excellent with forests now well filled in above 4500 ft.

 

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