Avalanche Forecast

Issued: Apr 13th, 2015 9:12AM

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

swerner, Avalanche Canada

South Coast.

Tricky winter conditions exist at higher elevations. Spring-like, convective weather directly influences the snowpack and avalanche hazard can change quickly. Use a conservative approach and watch for signs of instabilities.

Summary

Confidence

Fair - Due to the number of field observations

Weather Forecast

Winter continues on the coast as an upper trough moves across the province. A cool and unstable airmass will bring spring-like convective conditions including sunshine, moderate westerly ridgetop winds and localized snow squalls. Tuesday will mostly be a mix of sun and cloud with freezing levels near 1200 m and precipitation 2-5 mm. Wednesday will remain mostly cloudy with moderate to strong westerly ridgetop winds. Thursday, strong ridgetop winds will howl from the west and precipitation amounts are minimal. Freezing levels will hover around 1300 m on Thursday and the rise throughout the day to 2500 m Friday night.

Avalanche Summary

No reports of avalanche activity from yesterday. This is most likely as a result of few field observations. I suspect wind slab activity with new loading and strong winds and solar aspects may become active again when the sun come out. Watch overhead hazards like cornices.

Snowpack Summary

Anywhere from 30 to 50 cm of recent storm snow sits on a variety of old surfaces including crusts, surface hoar and facets that were buried April 10th. Moderate to strong south west winds are redistributing the storm snow into wind slabs on leeward slopes and terrain features. Â The mid-March persistent weak layer of facets on a crust is now approximately 50-100 cm down. Â This remains a concern in the region due to its potential to produce very large avalanches. There may be a low probability of triggering this layer, however; if it is triggered the consequence would be high. Large looming cornices may become weak with solar radiation and daytime warming. If a cornice fails it could trigger a large avalanche from the slope below.

Problems

Wind Slabs

Strong winds have built wind slabs in lee terrain in the alpine and at treeline. They are especially touchy where they sit on buried facets, surface hoar and/ or crusts. Weak, looming cornices may fail with solar radiation.

Avoid freshly wind loaded features.>Whumpfing, shooting cracks and recent avalanches are all strong inicators of unstable snowpack.>Give cornices a wide berth when travelling on or below ridges.>

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

Elevations: Alpine, Treeline.

Likelihood

Likely

Expected Size

1 - 3

Persistent Slabs

No recent activity has been reported on this layer, but it's still there, and could produce a large avalanche if triggered. Large loads like cornice fall, or hitting the sweet spot in thin-thick snowpack areas could act as a trigger.

Be aware of thin areas that may propogate to deeper instabilites.>Smaller surface avalanches and cornice fall could act as a trigger, initiating avalanches on the deeper buried weak layer.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Unlikely - Possible

Expected Size

2 - 5

Valid until: Apr 14th, 2015 2:00PM