Boletín de aludes

Northwest Coastal

Jan 2 – 3, 2022Avalanche Canada
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Archivado · caducó 5 years ago

Peligro de aludes

Tue
Wed
Alta montaña
3 · Notable
Límite del bosque
3 · Notable
Bajo el límite
3 · Notable

Lo esencial

Up to 80 cm of recent snow has created touchy storm slabs that will be most reactive in wind affected terrain.

Use small, low consequence slopes to test the bond of the new snow and watch for newly formed wind slabs as you transition into wind affected terrain. 

Problemas de aludes

  • Storm Slabs

    • Alta montaña
    • Límite del bosque
    • Bajo el límite del bosque
    Probabilidad
    Likely
    Tamaño
    1.5–3

    Up to 80 cm of recent snow and strong winds from a variety of directions have created touchy storm slabs at all elevations.

    The freshly formed slabs may remain reactive for longer than is typical because they are sitting on weak facets (sugary snow).

Weather Forecast

SUNDAY NIGHT: Cloudy with flurries; 3-10 cm / Strong east wind / Low of -20

MONDAY: Mix of sun and cloud with isolated flurries; 0-5 cm / Moderate northeast wind / High of -16

TUESDAY: Sunny / Light east wind / High of -21

WEDNESDAY: Sunny / Light variable wind / High of -22

Avalanche Summary

Natural and human triggered storm slab avalanches up to size 2 were reported at all elevations on Saturday.

Natural and human triggered avalanches remain likely on Monday. If you see any avalanche activity, please let us know by filling out a Mountain Information Network report. ?

Confidence

Moderate - Uncertainty is due to the limited number of field observations.

Snowpack Summary

A significant storm impacted the region on Saturday bringing upwards of 60 cm of new snow. In open areas, winds created deep deposits of wind slab in lee features. In sheltered areas the new snow formed a touchy storm slab or loose dry avalanche problem. On Sunday, strong southeast outflow winds formed fresh, reactive wind slabs in atypical reverse-loading and cross-loading patterns which could catch riders off guard.

The new snow likely bonded poorly to the old surface, and reactivity may persist into today. The old surface was comprised of hard wind slab, sastrugi, and near surface faceting formed from previous variable winds and two weeks of prolonged cold temperatures. 

Two layers of surface hoar exist within the upper snowpack in protected areas at treeline and below; one is down 40-60 cm (Dec 21) and the other is down 60-100 cm (Dec 18). The distribution of these layers appears to be relatively isolated, but information is limited and there has been very little feedback with recent benign weather pattens.

The early December rain crust is up to 10cm thick, down 80-150cm in the snowpack, and exists to an average of 1400m in elevation. Up to 2mm facets have been reported above this crust, and it is producing hard but sudden planar results in snowpack tests in areas north of Terrace. 

The lower snowpack is well settled, with several decomposing early season crusts. Snowpack depths vary greatly across the region, expect to find anywhere from 140-300 cm of snow around treeline, with highest amounts in coastal areas.

Terrain and Travel

  • Continue to make conservative terrain choices while the storm snow settles and stabilizes.
  • Look for signs of instability: whumphing, hollow sounds, shooting cracks, and recent avalanches.
  • Use small low consequence slopes to test the bond of the new snow.
  • Be aware of highly variable recent wind loading patterns.
  • Watch for newly formed and reactive wind slabs as you transition into wind affected terrain.

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