Archived

Avalanche Forecast

Dec 29th, 2017–Dec 30th, 2017

Alpine

2: Moderate

The avalanche danger rating in the alpine will be moderate

Treeline

1: Low

The avalanche danger rating at treeline will be low

Below Treeline

1: Low

The avalanche danger rating below treeline will be low

Alpine

2: Moderate

The avalanche danger rating in the alpine will be moderate

Treeline

1: Low

The avalanche danger rating at treeline will be low

Below Treeline

1: Low

The avalanche danger rating below treeline will be low

Alpine

2: Moderate

The avalanche danger rating in the alpine will be moderate

Treeline

2: Moderate

The avalanche danger rating at treeline will be moderate

Below Treeline

2: Moderate

The avalanche danger rating below treeline will be moderate

Regions: 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.

Confidence

Moderate - Due to the number of field observations

Weather Forecast

SATURDAY: Mostly sunny. Ridge wind moderate west. Temperature -15. Freezing level surface.SUNDAY: Mostly cloudy. Ridge wind light northwest. Temperature -12. Freezing level surface.MONDAY: Cloudy, flurries. Accumulation 5-10 cm. Ridge wind moderate southwest. Temperature -5. Freezing level 400 m.

Avalanche Summary

On Thursday an isolated wind slab release (size 1.5) was observed on an actively wind loading, steep terrain feature in the northern part of the region. And on Sunday, a skier remotely triggered a large wind slab (size 2) near the Shames area. The avalanche was triggered on a steep south-facing rocky ridgetop at 1400 m. Check out the Mountain Information Network (MIN) report here for details. And please post your own observations to the MIN!

Snowpack Summary

The Arctic high remains in place and strong outflow winds 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. Winds have come from a variety of directions over the past several days and have built wind slabs in much of the alpine and exposed treeline terrain. These wind slabs rest on a variety of old surfaces including a thick melt-freeze crust that formed in mid-December. In some sheltered locations, soft feathery surface hoar crystals may exist on top of this crust. In non-wind affected terrain, 30-40 cm of unconsolidated snow overlies the mid-December crust layer.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.

Avalanche Problems

Wind Slabs

Wind slabs are likely 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.

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

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

Elevations: Alpine, Treeline.

Likelihood: Unlikely - Possible

Expected Size: 1 - 2