Avalanche Forecast

Issued: Feb 22nd, 2014 7:51AM

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

Avalanche Canada Peter, Avalanche Canada

Conditions are primed for triggering avalanches. Conservative decision making is essential. Check out the latest forecaster blog for more discussion on the current conditions.

Summary

Confidence

Fair - Intensity of incoming weather systems is uncertain

Weather Forecast

Synopsis: One more warm front should pass across the South Coast late Sunday spreading light to moderate snowfall through Monday morning. A ridge of high pressure builds in on Monday kicking off a drying trend. Sunday: Flurries or light snow – 5-10 cm. The snow line is near sea level. Ridge winds are moderate from the W-NW. Monday: Flurries ending early, followed by a mix of sun and cloud. The freezing level is around 500 m. Winds are moderate from the north, easing to light. Tuesday: A mix of sun and cloud. The freezing level is around 1000 m. Winds are light.

Avalanche Summary

A number of very large (size 3-4) natural and explosive triggered slab avalanches occurred near the Coquihalla Pass on Friday. These events were in response to rapid loading from new snowfall and strong winds and showed impressive propagation. In other areas natural activity was limited to relatively small moist loose snow avalanche from solar aspects. Whumpfing and cracking continue to be reported and the potential for triggering the mid-February persistent weakness remains high.

Snowpack Summary

In the last week, the northern part of the region received over 1 m of new snowfall, while southern areas saw almost 2.5 m (and counting). Strong winds have created dense wind slabs on exposed lee slopes and in cross-loaded terrain features. In the southern portion of the region the new snow sits on a crust/facet combination along with old wind slabs on lee slopes. In the northern part of the region one can add surface hoar to the crust/facet/slab combination. Recent snowpack tests generally give moderate sudden "pops or drops" shears on this weakness and show potential for wide propagation. The mid and lower snowpack are generally strong and well-settled. Although basal facets and depth hoar are likely to exist in the north of the region, giving us a low probability, but high consequence of a large destructive avalanche.

Problems

Persistent Slabs

An icon showing Persistent Slabs
A persistent weakness, now down 60-80 cm in the northern part of the region and 100-150 cm in the south, is primed for rider triggering. This tricky problem has the potential for wide propagation and very large avalanches.
Whumpfing, shooting cracks and recent avalanches are all strong inicators of unstable snowpack.>Stick to simple terrain and be aware of what is above you at all times.>Be aware of the potential for large, deep avalanches due to the presence of buried surface hoar.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Likely - Very Likely

Expected Size

1 - 7

Wind Slabs

An icon showing Wind Slabs
Strong winds have formed fresh wind slabs in lee and cross-loaded terrain. A thin wind slab couldĀ  potentially trigger the deeper persistent weakness and result in a very large avalanche.
Avoid freshly wind loaded features.>Minimize overhead exposure; avalanches triggered by windloading may reach run out zones.>

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

Elevations: Alpine, Treeline.

Likelihood

Likely - Very Likely

Expected Size

1 - 5

Valid until: Feb 23rd, 2014 2:00PM

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