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Avalanche Forecast

Archived

Nov 24th, 2015–Nov 25th, 2015

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

Regions

Sea To Sky.

The snowpack is extremely variable depending on aspect and elevation. Use a cautious approach to terrain features and gather info along the way. Check out the Mountain Information Network. Give info, get info?

Confidence

Poor - Due to the number and quality of field observations

Weather Forecast

As the Arctic front moves through today and tonight, temperatures will and drop and strong northerly winds will persist, especially over the south coast. Wednesday, the high pressure will settle over the province giving cool and dry conditions. Treeline temperatures will hover near -3 with light winds from the northeast. Late Wednesday, warm air aloft will start to invade the coastal regions allowing temperatures to rise near 0-3 degrees up to 2500 m through Friday, and then potentially up to plus 5 degrees through the weekend. Ridgetop winds will remain L-M from the north-north east, and switch as the warmer air mass takes over on the weekend.

Avalanche Summary

On Monday, numerous skier controlled storm slabs up to size 1-1.5 slab avalanches were reported from northerly, wind loaded aspects above 2000 m. The new storm snow may need some time to settle out and adjust to the old snow surfaces. New wind slabs may be found on opposite slopes with the changing winds and rider triggered avalanches are possible-likely. Its still early season and travel remains rugged to higher elevations. Remember, the snowpack and avalanche problems are extremely variable depending on aspect and elevation.

Snowpack Summary

New storm snow amounts range from 10-20 cm. Initially, the storm arrived with strong southwest winds leaving lee slopes with deeper deposits. This new snow will likely have a poor bond to the old surfaces that comprise of surface hoar, crusts (potentially up to 2100 m) and some dry facetted snow above that. Forecast changing winds (outflow from the north) will likely redistribute the new snow on opposite slopes building new wind slabs that could catch you by surprise. Snowpack depths are highly variable across the region. Below treeline the snowpack remains below threshold for avalanche activity. Where the buried crust is thick, avalanches failing on deeper layers beneath have become much less likely. My uncertainty lies deeper in the snowpack where older persistent weak layers may exist. Reports indicate that these shears are resistant in the moderate to hard range, however; I'd remain extra cautious in areas where the old crust is thin or has not formed (I'm thinking high alpine terrain or northern parts of the region). They may still be sensitive to rider triggering.

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.