Avalanche Forecast

Issued: Jan 24th, 2017 5:11PM

The alpine rating is moderate, the treeline rating is moderate, and the below treeline rating is low. Known problems include Wind Slabs.

Avalanche Canada cgarritty, Avalanche Canada

Keep your objectives in check as stability improves. Wind slabs are distributed widely and may step down to deeper weaknesses in thin snowpack areas.

Summary

Confidence

High - The weather pattern is stable

Weather Forecast

Wednesday: Mainly cloudy with isolated flurries and a trace of new snow. Winds light from the west. Freezing level around 700 metres with alpine temperatures around -7. Thursday: Mainly cloudy with isolated flurries and a trace of new snow. Winds light from the southwest. Freezing level around 800 metres with alpine temperatures around -6. Friday: Mainly cloudy with isolated flurries and a trace of new snow. Winds moderate from the southwest. Freezing level around 1000 metres with alpine temperatures to -3, possibly exceeding 0 in the south of the region.

Avalanche Summary

While no new avalanches were reported in the region on Monday, a natural Size 1.5 cornice release in the Pemberton area serves as a good reminder of cornices having matured considerably over the course of the recent storm. Reports from Sunday included an impressive natural avalanche cycle observed in the South Chilcotin, where three Size 2.5-3 avalanches occurred on adjacent southwest-facing slide paths within 2 hours of each other. The crown fractures averaged a metre in depth and all initiated at treeline elevation. Direct sunlight was determined to be the trigger of these slides. Another MIN post from Monday details an apparently naturally triggered Size 3.5 avalanche releasing above Upper Joffre Lake on Sunday.

Snowpack Summary

SOUTHERN AREAS (e.g. Coquihalla): 10-20cm of snow from last week appears to be bonding well to the previous rain-soaked snow surface up to treeline elevations. At alpine elevations, up to 40cm of storm snow fell with some wind slabs forming on northerly aspects. NORTHERN AREAS (e.g. Duffey Lake): Up to 45 cm of fresh snow by Friday morning brought the storm snow totals to over a metre, which was all redistributed by moderate to strong southerly winds. This resulted in touchy storm and wind slabs bonding poorly to the previous snow surface that includes facets and large surface hoar on sheltered slopes and/or a sun crust on steep sun-exposed aspects, as well as wind-affected surfaces (e.g. hard wind slab, sastrugi, scoured crust, etc.) in exposed areas. Weaknesses within the recent storm snow have been settling, but the bond of the storm snow to the previous cold snow surface from over a week ago is less reliable. Thin snowpack areas such as the South Chilcotin mountains remain the most likely to harbour this and other persistent weaknesses.

Problems

Wind Slabs

An icon showing Wind Slabs
Weaknesses exist within and under the new snow. Slabs will be particulary touchy on wind-loaded aspects near ridge crests. In low snow areas, keep in mind the possibility for a wind slab avalanche to "step down" to the weak layer below our new snow.
Be aware of the potential for wide propagations.If triggered the wind slabs may step down to deeper layers resulting in large avalanches.Use caution in lee areas. Recent wind loading has created wind slabs.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 3

Valid until: Jan 25th, 2017 2:00PM

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