Bollettino valanghe

West Slopes South

Northwest Avalanche Center
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Pericolo valanghe

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

In sintesi

Warm and sunny weather should destabilize the snow surface and produce wet avalanches on Sunday. If you notice the snow surface getting warm and sticky, choose travel routes in shadier terrain away from blocks of snow and ice above you. The potential for large and destructive avalanches in wind-loaded terrain still exists as you ascend in elevation.

Problemi valanghivi

  • Loose Wet

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

    Temperatures are ready to soar around the West South on Sunday only a few days after a potent storm pummeled our zone. This warmup will have different effects depending on your location, but the highest hazard should generally be found in wind-sheltered areas above the recent rain/snow line. A cool breeze may help limit wet loose avalanches in some areas of the zone, but may not eliminate the hazard. Regardless of your location, if you find yourself in the sunshine and the snow surface is getting sticky and wet, you should start thinking about wet avalanches. Look for snow shedding from trees and rocks or pinwheels and rollerballs as precursors to wet avalanches. Wet Loose avalanches often start at a point, can entrain significant snow or trigger slabs, and will fan out as they descend downhill. If you notice these signs, head for shadier slopes keeping aware of the slopes above you.

    Also, watch out for blocks of snow and ice falling from trees and structures as temperatures rise on Sunday. These can be as big of a hazard as any conventional avalanche.

    (1/8/2022)

    Wet avalanche debris was found along the road to Paradise by NWAC forecasters and NPS rangers on 1/8. Expect more wet avalanches as temperatures warm and the snow surface destabilizes.

    Photo: Dallas Glass

  • Wind Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Possible
    Dimensione
    2–2.5

    Continue to be leery of wind-loaded terrain at middle and upper elevations on Sunday. These Wind Slabs may be a bit stiffer than you are used to and straddle a line between soft slab and hard slab. Look for freshly built cornices, textured snow surfaces, and wind-stiffened snow that may feel hollow as indicators of wind-loaded terrain to avoid. With so much recent snow and strong winds, these slabs could be several feet thick in high alpine terrain and produce very large avalanches like the one at Crystal Mountain on Friday. Freshly built cornices getting baked by Sunday’s warm weather could fall and act as a trigger for these larger Wind Slabs. Take care on open slopes near ridgelines and give cornices a wide berth by not getting too close to them or traveling under them. They notoriously break further back than expected.

    (1/8/2022)

    This very large avalanche was triggered by explosives on 1/7. The very deep (4-6') and wide (500ft) failed on an old snow layer, grew very large (D4) and broke trees. HS-AE-R4-D4-O, NE, 6800. 

    Photo: Crystal Mountain

Avalanche Discussion

We are starting to get a bit more information about conditions around the zone as we dig ourselves out from the recent storm. White Pass Pro Patrol and WSDOT avalanche crews reported a recent widespread natural cycle, freshly built cornices, and a slight freezing rain crust capping the storm snow at lower elevations. NWAC forecasters and NPS rangers reported a similar story, with multiple natural avalanches (D2+) hitting the road to Paradise and 18” of heavy snow sitting above a rain crust, capped by a thinner rime crust. At Crystal, large test shots during control work did not produce any notable results only a day after a D4 avalanche broke timber and ran close to its historic runout zone. As mentioned above, we still have a high degree of uncertainty. Above the recent snow/rain line, conditions are expected to be very different than where most of our recent observations have come from. With soaring temperatures and cold winter snowpack, we expect wet avalanche activity to be widespread at these elevations. Conditions may range throughout the zone, so make your own observations about how the weather is playing out in your area. Sunday may not be the day to step directly into consequential terrain. 

If you are out and about in the nice weather and notice recent avalanche crowns or debris piles, please take a picture and share it with us as we try to track and document this cycle. The evidence of these avalanches may be hidden by some fresh snow sitting atop them, but we’d appreciate a picture of anything you suspect is an avalanche. Other useful information to accompany a picture is the location of the avalanche, along with aspect and elevation if possible. You can submit this information on our observation platform either privately or publicly. 

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