Avalanche Forecast

Issued: Apr 14th, 2015 9:35AM

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

Sea To Sky.

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 - Intensity of incoming weather systems is uncertain

Weather Forecast

The current weather pattern is more winteresque than it has been all season. Im beginning to feel seasonally confused. Unsettled conditions expected as the next front passes. Behind this front, a moist onshore flow will be directed to coastal regions bringing precipitation and strong winds, especially to upslope areas. Wednesday will see a mix of sun and cloud, strong westerly ridgetop winds and freezing levels rising to 1500 m. On Thursday, anywhere from 10-20 mm of precipitation is expected with strong west winds and freezing levels near 1500 m. On Friday a strong ridge of high pressure will build and bring clear sunny skies accompanied by rising freezing levels to 2500 m.

Avalanche Summary

No recent observations. On Monday, no natural activity was reported but numerous size 1 storm slabs were easily triggered by the weight of a skier, especially in areas that saw some wind effect.

Snowpack Summary

Upper elevations have received 25-40 cm of recent storm snow. The new snow sits on a variety of old snow surfaces including crusts, facets and spotty surface hoar which was buried on April 10th. This interface has shown a poor bond and has been reactive naturally and to human triggers. Moderate to strong south west winds has redistributed the recent storm snow into wind slabs on leeward slopes and behind terrain features. The mid-March persistent weak interface has been producing hard but sudden planar results in snowpack tests. This remains a concern in the region. 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. Give looming cornices a wide berth if the sun comes out.

Pay attention to overhead hazards like cornices, especially when the sun is shining.>Watch for whumpfing, hollow sounds, shooting cracks or recent avalanches.>Avoid freshly wind loaded features.>

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

Elevations: Alpine, Treeline.

Likelihood

Possible - 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.

Avoid convexities or areas with a thin or variable snowpack.>Be aware of the potential for large, deep avalanches due to the presence of a buried crust/facet layer.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Unlikely - Possible

Expected Size

2 - 5

Valid until: Apr 15th, 2015 2:00PM