Bollettino valanghe

Kootenay Boundary

Jan 20 – 21, 2013Avalanche Canada
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Archiviato · scaduto 14 years ago

Pericolo valanghe

Tue
Wed
Alta quota
2 · Moderato
Limite del bosco
1 · Debole
Sotto il limite
1 · Debole
Apri la mappa completa

In sintesi

Problemi valanghivi

  • Wind Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Possible
    Dimensione
    1–4
    Previous extreme winds out of the W/NW left hard slabs, soft slabs, sastrugi and potentially unstable cornices in their wake. Many of these slabs have grown old and tired, but the odd sensitive slab may still be lurking out there.

  • Persistent Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Unlikely
    Dimensione
    1–5
    While unlikely, it may still be possible to trigger this layer on the odd slope.  I'm thinking about a steep rocky slope with a snowpack thinner than the regional average.  Sensitivity may increase slightly Monday with warm temps and direct sun.

Confidence

Fair - Timing, track, or intensity of incoming weather is uncertain on Wednesday

Weather Forecast

Monday: Inversion. Freezing level at surface. Above freezing layer from 1500m – 2500m. Ridgetop winds Mod NW. Treeline winds light W. No precip. Scattered cloud, clearing in the afternoon.Tuesday: Should be the last inverted day. Freezing level at surface. Above freezing layer from 1500m – 3000m. Ridgetop winds Mod W. Treeline winds light SW. No precip.  Broken cloud cover for most of the day.Wednesday: Freezing level at valley bottom. Snow beginning Tuesday night, carrying into Wednesday.  I expect around 5 cm by Wednesday morning with an additional 5 – 10 during the day Wednesday.  Ridgetop winds initially light SW, steadily increasing to strong NW by late afternoon.

Avalanche Summary

No new natural activity. On Saturday a size 2 avalanche was spotted that was suspected to be sled triggered.  It was just below ridgetop on an east aspect at 2200m.  On Friday a group of skiers triggered a small (size 1.5) hard slab avalanche the failed when the 3rd skier traversed across an east facing slope at 2000m.

Snowpack Summary

Savage winds out of the NW have wreaked havoc on the region. N & W facing slopes are wind pressed or wind-stripped. Slopes lee to these winds were left with wind slabs up to a meter in depth in open areas. While the results of the recent winds appear dramatic, the wind slabs are quite stubborn in their trigger-ability for the most part.  There are of course, exceptions, see the recent avalanche observations. Warm temperatures have created moist snow that can be found on almost all aspects up to 2300m. Protected areas are growing surface hoar to 20mm, while many other slopes are sporting a zipper crust due to the warm temps. Under the snow surface lies the January 4th interface, down around 75 cm & obviously much deeper in wind loaded areas. This layer of small/facets/crusts and intermittent surface hoar is producing planar shears in some drainages and no failure at all in others. At the moment it's tough to find soft snow to recreate in. The midpack is well good, nicely bonded and strong.

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