Avalanche Forecast

Issued: Dec 19th, 2018 4:07PM

The alpine rating is high, the treeline rating is high, and the below treeline rating is considerable. Known problems include Storm Slabs and Persistent Slabs.

mconlan, Avalanche Canada

South Coast Inland.

HIGH danger is forecast for Thursday. Expect rapid snow loading and very strong winds. It is a good day to avoid avalanche terrain and stick to sufficiently low-angled slopes and densely-spaced trees.

Summary

Confidence

Moderate - Timing, track, or intensity of incoming weather system is uncertain

Weather Forecast

WEDNESDAY NIGHT: Cloudy with light snowfall, accumulation 5 to 10cm. THURSDAY: Cloudy with snowfall, accumulation 20 to 30cm with local amounts up to 50cm, strong to extreme southwest winds, alpine temperature -1Â°c, freezing level rising to 1600m over the day. FRIDAY: Partly cloudy, moderate west winds, alpine temperature -9Â°c, freezing level 600m. SATURDAY: Cloudy with light snowfall, accumulation 5cm, moderate southwest winds, alpine temperature -7Â°c, freezing level 500m.

Avalanche Summary

There was a report of natural avalanche in the Duffey Lake Road area on Monday. This appears to be a size 2 that was 60 cm thick and 80 m wide on a southeast slope at tree line. Click here to see the MIN post. Expect to see similar avalanches during Thursdays storm.

Snowpack Summary

Up to 40 cm of snow fell on Wednesday around the Coquihalla, with substantially lesser amounts in the north of the region. We are in the midst of another storm impacting the region on Thursday, which will bring more snow and strong to extreme southwest winds. Expect the new snow to be reactive to both skier activity and natural triggers.A weak layer of facets and surface hoar lies below all this storm snow. While the layer is likely gaining strength, field observations show that slab avalanches remain possible on this layer where it exists.Near the base of the snowpack, a crust exists with weak and sugary facets beneath it. This could potentially still be of concern in high north-facing aspects where the snowpack rests on very smooth ground cover. Elsewhere, this layer is no longer a concern.

Problems

Storm Slabs

Expect new snowfall to be reactive to human traffic. Deeper slabs will exist in lee terrain features due to strong south winds.

Use ridges or ribs to avoid pockets of wind-loaded snow.Be cautious as you transition into wind affected terrain.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Likely - Very Likely

Expected Size

1 - 2.5

Persistent Slabs

A weak layer buried approximately 70 cm below the surface has the potential to produce large avalanches. This layer is likely most problematic in the north section of the region.

Use conservative route selection, choose moderate angled and supported terrain with low consequence.Watch for whumpfing, hollow sounds, shooting cracks or recent avalanches.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1.5 - 3

Valid until: Dec 20th, 2018 2:00PM