Bollettino valanghe

East Slopes Central

Northwest Avalanche Center
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Pericolo valanghe

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

Stay alert to changing conditions throughout the day and as you ascend. Upper elevation terrain may become textured by wind drifting as the day progresses. Wind slabs may be small, but you could trigger a larger avalanche on the higher peaks. Happy New Year!

Problemi valanghivi

  • Wind Slabs

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

    Winds should ramp up on Saturday and could transport the very low-density new snow into cohesive slabs.  You could trigger wind slabs on the leeward sides of exposed features including ridges and mid-slope features. Slabs could be larger at higher elevations where more drifting takes place. With weak snow recently covered, slabs that are cohesive could be triggered from unlikely places.

    Look for signs of instability such as recent slab avalanches, and shooting cracks. Steer around steep slopes with stiffer snow, drifted snow, and wind rippled snow. In many areas of the zone you could find weaker snow near the ground. Slides in heavily wind-loaded areas have the potential to step down to these deeper layers, and become much larger avalanches. Use safe travel protocols and consider each slope separately. Fresh cornices may also be fragile, so stay well away from them.

    In very steep areas, you may be able to initiate dry loose avalanches. These 'sluffs' may not be too dangerous if you manage terrain wisely, but can cause problems if you find yourself in the wrong terrain.

    (12/28/2021)

    Shallow recent wind slab beneath a cornice. The slide appears to have stepped down to a deeper layer. N at 7,200ft on Mt Cashmere.

    Photo: Matt Primomo

Avalanche Discussion

On the last day of 2021, the East Central picked up another couple of inches, and from 3" to 12"+ on Thursday. With this last storm, the winds were strong initially but quickly subsided while the snow fell, and have been fairly quiet since. Mission Ridge reported triggering a few small wind slabs and fairly long running loose avalanches on New Years Eve. Expect a marked increase in winds for New Years Day that should stir up lots of loose snow. Before this last storm, observers had noted weak snow surfaces due to the very cold temperatures last week. Avalanche activity can be expected to increase the first week of the new year, as slabs build up over these weaker layers.

The storm snow from December has generally been settling out, although at it's base a weaker structure exists in many areas. An observation from the Icicle Creek drainage on the 28th showed that weaker snow has formed between deeply buried crusts from earlier in December. A very large avalanche was observed off of Mt Mastiff, on the eastern edge of the neighboring Steven’s Pass zone. A thin crust from the Solstice is now buried 20 to 30 inches in western parts of the zone and 8-15 inches in eastern areas. Cold temperatures have likely contributed to weakening of bonds between many crust interfaces. Above 6000ft, this crust may be difficult to discern or might not have formed at all. While triggering a slide on these deeper interfaces appears unlikely, caution is warranted in larger, alpine terrain of the region.

If you get out please post to our observation page, and help contribute to the forecast!

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