Avalanche Forecast

Issued: Dec 30th, 2017 4:19PM

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

mgrist, Avalanche Canada

Northwest Coastal.

Pockets of reactive wind slab remain a concern for wind-exposed alpine and treeline areas. New snow and wind on Monday will heighten avalanche danger.

Summary

Confidence

Moderate - Due to the number of field observations

Weather Forecast

Cool temperatures until light precipitation arrives on Monday. SUNDAY: Mostly cloudy. Ridge wind light northwest. Temperature -12. Freezing level surface.MONDAY: Cloudy, flurries. Accumulation 5-10 cm. Ridge wind moderate to strong southwest. Temperature -5. Freezing level 400 m.TUESDAY: Cloudy with isolated flurries. Ridge wind moderate south west. Temperature -5. Freezing level 500m.

Avalanche Summary

On Thursday an isolated wind slab release (size 1.5) was observed on an actively wind loaded, steep terrain feature in the northern part of the region.

Snowpack Summary

Cold temperatures and strong winds (from the south east, and more recently from the west) have affected the surface snow over the past week, scouring some slopes down to an old crust and forming hard deposits in many other areas. There are some lingering wind slabs, found on a variety of old surfaces including a thick melt-freeze crust that formed in mid-December. In non-wind affected terrain, 30-40 cm of unconsolidated (aka faceted or 'sugary') snow overlies the mid-December crust layer. This snow has been sluffing in steep terrain.Beneath the mid-December crust the snowpack is reported to be generally strong with the possible exception of areas around Stewart and northern parts of the region where the late-October, basal crust can be found near the base of the snowpack. Weak sugary snow may exist around this basal crust and could be triggered from shallow snowpack areas.

Problems

Wind Slabs

Wind slabs may be lingering around ridge crests, exposed gullies and cross-loaded slopes. These wind slabs may be poorly bonded to the buried mid-December crust layer and reactive to human triggers such as a skier or rider.

Watch for whumpfing, stiff or hollow sounding snow, and shooting cracks.Be cautious as you transition into wind affected terrain.

Aspects: North, North East, East, South East, South.

Elevations: Alpine, Treeline.

Likelihood

Unlikely - Possible

Expected Size

1 - 2

Valid until: Dec 31st, 2017 2:00PM