Avalanche Forecast

Issued: Feb 4th, 2020 5:00PM

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

Avalanche Canada MBender, Avalanche Canada

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Posted avalanche danger ratings are for the north of the region where a deep persistent avalanche problem continues to be a concern. Avalanche danger in the south of the region (Coquihalla and Manning areas) is MODERATE in the alpine.

Summary

Confidence

Moderate - Forecast snowfall amounts are uncertain.

Weather Forecast

Tuesday Night: Flurries, accumulation 5-10 cm. Moderate to strong southwest and west wind. Alpine high -8 C.

Wednesday: Flurries, accumulation 5 cm. Strong west wind. Alpine high -4 C. Freezing level 1200 m.

Thursday: Snow, accumulation 5-10 cm in the north of the region and 15-30 cm in the south. Moderate to strong west wind. Alpine high -2 C. Freezing level 1000 m.

Friday: Flurries, accumulation 5 cm. moderate west wind. Alpine high -4 C. Freezing level 1000 m.

Avalanche Summary

There have been no recent reports of avalanche activity. The deep persistent slab avalanche activity observed during last weekend's storm in the northern portion of the region seems to have tapered off. Although the likelihood of triggering has reduced there is is still concern for deep releases in that part of the region.

Snowpack Summary

Extreme southwest wind during the storm last weekend has scoured windward aspects, formed deep loaded pockets in alpine lees and contributed to rapid cornice growth. Below 1800 m, snow overlies a crust and tapers with elevation.

In the north part of the region (ie. Goldbridge/Duffey/Hurley), a few deep instabilities exist in the snowpack, including a weak basal facet crust complex. This has been the failure plane in ongoing reports of very large, deep persistent avalanches.

The south of the region, including the Coquihalla and Manning areas, currently have no concerns about deeply buried weak layers.

Terrain and Travel

  • Be especially cautious as you transition into wind affected terrain.
  • Make conservative terrain choices and avoid overhead hazard.
  • Use extra caution around cornices: they are large, fragile, and can trigger slabs on slopes below.
  • If triggered, wind slabs avalanches may step down to deeper layers resulting in larger avalanches.

Problems

Deep Persistent Slabs

An icon showing Deep Persistent Slabs

Although the likelihood of triggering a deep persistent slab avalanche has reduced, doing so would result in a large and destructive avalanche. These layers do not pose an avalanche problem in the south half of the region.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

2.5 - 4

Wind Slabs

An icon showing Wind Slabs

Strong to extreme winds during last weekend's storm have created thick deposits of wind loaded snow in lee terrain features.

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

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 2

Valid until: Feb 5th, 2020 5:00PM