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Avalanche Forecast

Archived

Jan 15th, 2012–Jan 16th, 2012

Alpine
Natural avalanches unlikely, human triggered possible.
Treeline
Natural avalanches unlikely, human triggered possible.
Below Treeline
Natural avalanches unlikely.
Alpine
Natural avalanches unlikely, human triggered possible.
Treeline
Natural avalanches unlikely, human triggered possible.
Below Treeline
Natural avalanches unlikely.
Alpine
Natural avalanches unlikely, human triggered possible.
Treeline
Natural avalanches unlikely, human triggered possible.
Below Treeline
Natural avalanches unlikely.

Regions

Kootenay Boundary.

Confidence

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

Weather Forecast

MONDAY: Light precipitation with gradually cooling temperatures to -13 degrees celsius. Winds light from the west and southwest. TUESDAY: Light flurries and continued colder temperatures. Light to moderate westerly winds. WEDNESDAY: The northern edge of a frontal system over Washington state bringing light to moderate precipitation to the region. Light westerly winds.

Avalanche Summary

Recent reports indicate loose snow avalanches to size 1 triggering easily in steep unsupported terrain.

Snowpack Summary

Continued small amounts of snow has maintained fresh wind slab development and cornice growth. This latest new snow has buried a some previously facetted surface snow and small surface hoar in sheltered areas at and below treeline. A thin melt/freeze crust can be found in the upper snowpack as high as 1900m, and some areas are reporting surface hoar buried early-January now down 10-30cm. The late-December interface is now down 30-60cm and producing moderate to hard resistant snowpack test results. The mid-December surface hoar/facet persistent weakness, down 40-100cm, is generally producing anywhere from easy results where it's shallow to hard results where it's deeper. Basal facets remain concern in shallow snowpack areas especially with heavy triggers in thin spots, and weaknesses in the slab above create the potential for step-down avalanches.

Problems

Wind Slabs

Wind Slab avalanches are the release of a cohesive layer of snow (a slab) formed by the wind. Wind typically transports snow from the upwind sides of terrain features and deposits snow on the downwind side. Wind slabs are often smooth and rounded and sometimes sound hollow, and can range from soft to hard. Wind slabs that form over a persistent weak layer (surface hoar, depth hoar, or near-surface facets) may be termed Persistent Slabs or may develop into Persistent Slabs.

Persistent Slabs

Persistent Slab avalanches are the release of a cohesive layer of snow (a slab) in the middle to upper snowpack, when the bond to an underlying persistent weak layer breaks. Persistent layers include: surface hoar, depth hoar, near-surface facets, or faceted snow. Persistent weak layers can continue to produce avalanches for days, weeks or even months, making them especially dangerous and tricky. As additional snow and wind events build a thicker slab on top of the persistent weak layer, this avalanche problem may develop into a Deep Persistent Slab.