Avalanche Forecast

Issued: Feb 14th, 2018 5:30PM

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

Avalanche Canada shorton, Avalanche Canada

Wind slabs exist on a wide range of aspects and may be hidden by the most recent snow.

Summary

Confidence

High -

Weather Forecast

THURSDAY: Increasing cloud with light flurries in the evening, moderate to strong northwest wind, alpine high temperatures around -10 C in the north and -6 C in the south.FRIDAY: Flurries easing throughout the day with 5-10 cm of new snow in the south and trace amounts in the north, moderate to strong northwest wind, alpine high temperatures around -8 C in the north and -4 C in the south.SATURDAY: Moderate snowfall with 10-25 cm throughout the day, strong southwest wind, alpine high temperatures around -8 C in the north and -4 C in the south.

Avalanche Summary

No new avalanches were observed in the Coquihalla area on Wednesday, while several size 2 wind slabs (40 cm thick) were triggered with explosives on south-facing slopes in the Duffey area. On Tuesday, a small (size 1) wind slab was triggered by a skier on a small west facing feature in the northern part of the region.Reports from the weekend included numerous small wind slabs releasing with skier traffic on steep treeline and alpine features, as well as a few large (size 2-3) naturally triggered slabs in the northern part of the region (some of which were triggered by cornices).

Snowpack Summary

10-20 cm of new snow sits above a variety of old interfaces, including unconsolidated snow in sheltered areas, scoured and wind loaded snow in exposed areas, and a melt-freeze crust below roughly 1900 m. Storm snow amounts from the past week are roughly 60 cm in the south of the region and about half this amount in the north of the region. About 80-150 cm down in the mid snowpack sits the mid-January crust. It generally shows signs of bonding to the overlying snow but will likely remain sensitive to large triggers - especially in thinner snowpack areas. Large, looming cornices exist, they are fragile, and they demand respect. Cornice falls are very effective triggers for avalanches on the slopes below them.

Problems

Wind Slabs

An icon showing Wind Slabs
Reactive wind slabs exist, especially around ridge crests where more wind loading has occurred. Recent shifting wind patterns have formed slabs on a wide range of aspects.
Be careful with wind loaded pockets, especially near ridge crests and roll-overs.Approach steep lee and cross-loaded slopes with caution.

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

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1 - 2

Cornices

An icon showing Cornices
Large, looming cornices have formed along ridgelines. They need to be given an extra wide berth from above and below. A large cornice collapse in the north of the region may have the ability to trigger a deeply buried weak layer.
Falling cornices may trigger large avalanches on slopes below.Firm cornices can pull back into flat terrain at ridgetop if they fail.

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

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1.5 - 3.5

Valid until: Feb 15th, 2018 2:00PM

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