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Avalanche Forecast

Archived

Dec 10th, 2019–Dec 11th, 2019

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

Northwest Coastal.

Slab avalanches will become increasingly easier to trigger as new snow accumulates.

Confidence

High - We are confident the likelihood of avalanche will increase with the arrival of the forecast weather.

Weather Forecast

TUESDAY NIGHT: Snow starting overnight with up to 5 cm by the morning, 30-40 km/h wind from the southwest, alpine temperatures drop to -5 C.

WEDNESDAY: Flurries increasing in intensity throughout the day with up to 20 cm near the coast and 5-10 cm further inland, 60 km/h wind from the south, freezing level up to 800 m, alpine high temperatures around -2 C.

THURSDAY: 10-20 cm of new snow, 40 km/h wind from the southwest, alpine high temperatures around -4 C.

FRIDAY: 5-10 cm of new snow by midday then clearing in the afternoon, 30 km/h wind from the southwest, alpine high temperatures around -4 C.

Avalanche Summary

No recent avalanches have been reported. On Sunday, warm alpine temperatures resulted in some small ice falls off of glaciers. A few small wind slab avalanches were triggered by skiers last Thursday and Friday.

Looking ahead, the main concern is new slabs forming above the surface hoar crystals that current sit on top of the snowpack. Over the next few days the likelihood of triggering storm slab or wind slab avalanches will increase as snow accumulates above this layer.

Snowpack Summary

Incoming stormy weather will bury a concerning layer of surface hoar that has formed in areas sheltered from the wind. As snow accumulates above this layer expect to find very reactive slabs. Reports suggest this layer can be found on all aspects up to treeline elevations. In the alpine, the new snow will bury hard wind slabs and sun crusts on south-facing terrain. The lower snowpack is generally considered strong and settled, as there has been very little to report in terms of recent avalanche activity or snowpack test results on deeper layers. Snowpack depths at treeline likely range from 90-160 cm and taper quickly at lower elevations.

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.