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Avalanche Forecast

Archived

Jan 2nd, 2014–Jan 3rd, 2014

Alpine
Natural avalanches possible, human triggered probable.
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

South Coast.

Confidence

Fair - Intensity of incoming weather systems is uncertain on Thursday

Weather Forecast

Friday: A mix of sun and cloud with isolated flurries possible in the morning, moderate NW winds and freezing levels dropping to 800m. Saturday and Sunday: Mostly sunny and dry with light W alpine winds and freezing levels around 900m.

Avalanche Summary

No avalanches were reported on Tuesday.

Snowpack Summary

New snow is expected to be poorly bonded, especially on wind-loaded slopes. Snowpack depths vary greatly across the region with 165cm at treeline in the Cascades but only about 65cm in the Duffey Lake area, and terrain below treeline is still mostly below threshold for avalanche activity. In general the snowpack is shallow with a faceted and weak lower half, but also highly variable. Snowpack testing on a SSE facing slope at 2000m in the Duffey Lake area on Monday produced easy to moderate, sudden collapse compression test results, and a RB3, whole block release Rutschblock result down 20cm on the mid-December surface hoar, as well as moderate sudden planar and RB1 results down 46cm on the late-November facets where they were found above a hard crust. However, these weak interfaces appear generally well bonded in the Cascades.Early season riding hazards such as rocks, stumps and logs are lurking below the surface at treeline elevations and below.

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.