Avalanche Forecast

Issued: Feb 8th, 2013 8:42AM

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

mpeter, Avalanche Canada

Sea To Sky.

Use caution at low elevations in the afternoon when the sun warms the recent storm snow, especially in areas that received more new snow.

Summary

Confidence

Good

Weather Forecast

Saturday: A ridge of high pressure builds and settles in. Expect mostly sunny skies, light northerly winds and alpine temperatures around -1.Sunday & Monday: The ridge continues to dominate. Expect continued sunny skies, light northerlies and high freezing levels in the afternoons.

Avalanche Summary

Reports continue of natural, explosive and rider triggered windslabs up to size 2.5 failing on northwest through east facing terrain. These are failing predominantly at treeline and in the alpine. Remote and accidental triggering have been observed. The south end of the region has seen the larger releases with wider propagation; at times linking terrain around ridge features. These areas have also seen storm slab events on open, convex features below treeline.

Snowpack Summary

The storm is over and a high pressure ridge is building in its wake. Storm snow amounts vary widely within the region, with 30cm in the north end of the region and up to 90cm at the south end. Consistent southerly winds during the storm period built windslabs in lee terrain and helped grow cornices.Newly buried surfaces (the Feb. 3 interface) include old windslabs, temperature and sun crusts. The new snow is bonding reasonably well at this interface in most locations with the highest concern being the bond to crusts on south and west facing terrain. The January 23rd interface (crusts, facets and surface hoar crystals) lingers in isolated locations. This layer seems to be rounding and bonding under current conditions, but we have reports of a recent size 2.0 releasing on this layer. The mid pack is generally well settled with the average snowpack depth at treeline around 180 cm.

Problems

Wind Slabs

Windslabs have formed at treeline and in the alpine due to consistent southwesterly winds. The new snow is bonding poorly in some locations where buried crusts are well developed.

Be cautious as you transition into wind affected terrain.>Use ridges or ribs to avoid pockets of wind loaded snow.>

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

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1 - 4

Cornices

Cornices have grown significantly with the recent storm and may be more prone to failure with daytime heating/solar radiation.

Cornices become weak with daytime heating.>

Aspects: North, North East, East.

Elevations: Alpine.

Likelihood

Unlikely - Possible

Expected Size

2 - 6

Loose Wet

When the sun comes out, expect the surface snow on south facing terrain to de-stabilize, especially at lower elevations.

Avoid sun exposed slopes when the solar radiation is strong, especially if snow is moist or wet.>

Aspects: North, North East, East.

Elevations: Alpine, Treeline.

Likelihood

Likely

Expected Size

1 - 3

Valid until: Feb 9th, 2013 2:00PM