Avalanche Forecast

Issued: Apr 10th, 2014 9:41AM

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

swerner, Avalanche Canada

South Coast.

Avalanche danger can rise very quickly with warming and solar radiation. Be aware of changing conditions and overhead hazards. Terrain choices and timing can be critical.

Summary

Confidence

Fair - Timing or intensity of solar radiation is uncertain

Weather Forecast

An upper level ridge will keep the region fairly dry and sunny. Solar radiation will be strong, and freezing levels could rise as high as 2500 m by Sunday.Friday: A mix of sun and cloud with isolated flurries. Ridgetop winds moderate from the West. Freezing levels rising to 1800 m.Saturday: Sunny skies. Alpine temperatures rising to 5.0 degrees. Ridgetop winds moderate from the North. Freezing levels rising to 1700 m.Sunday: Sunny. Alpine temperatures high of plus 5-10 degrees. Freezing levels rising to 2400 m then dropping overnight. Ridgetop winds light from the SW

Avalanche Summary

Cornices have started to fail with warmer temperatures and sunny skies up to size 2.5, without pulling deeper slabs on the slopes below. Numerous loose wet avalanches occurred up to size 2 on steeper solar aspects, and one isolated size 3 slab was observed from a distance in the Northern part of the region. Natural avalanche activity will likely spike with periods of solar radiation and warming.

Snowpack Summary

Up to 20 cm of new snow sits above a solid melt freeze crust. The new snow seems to be bonding with help from the warmer temperatures; however, isolated wind slabs likely exist. Surface snow has become moist, especially on southerly aspects forming melt-freeze conditions and surface hoar growth (4 mm) has been noted on shady slopes at higher elevations. Large sagging cornices threaten slopes from above and below.Snowpack tests have been producing hard resistant planar shears on the late March layer and the upper snowpack has strengthened.A couple persistent weak layers exist deeper in the snowpack. The March layer is down 60 - 100cm and the February layer is now deeply buried down 150 – 250 cm. These layers are mostly inactive at this time, but could re-awaken with extended warming, solar influence and large triggers like cornice fall.

Problems

Wind Slabs

Strong SW winds have set up isolated wind slab problems on leeward slopes, behind ridge crests and mid slope features like ribs/rock outcroppings. Sagging cornices may fail with warming and solar radiation. They could trigger the slope below.

Caution in lee and cross-loaded terrain near ridge crests.>Use ridges or ribs to avoid pockets of wind loaded snow.>Give cornices a wide berth when travelling on or below ridges.>

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

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 3

Loose Wet

With temperatures on the rise and intense solar radiation, loose wet avalanches are likely, especially on sunny slopes.

Avoid exposure to terrain traps where the consequences of a small avalanche could be serious.>Avoid slopes when temperatures rise and the surface snow becomes moist or wet. Signs of instability are pinwheels and natural avalanches. >

Aspects: North, North East, East.

Elevations: All elevations.

Likelihood

Likely

Expected Size

1 - 4

Deep Persistent Slabs

Three buried weak layers exist in the snowpack. Deep releases have become rare; however, the weak layers could be activated by cornice fall, a surface avalanche in motion.

Large triggers like cornice fall could initiate a deep persistent slab.>Be aware of the potential for large, deep avalanches due to the presence of buried facets and surface hoar.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Unlikely - Possible

Expected Size

3 - 7

Valid until: Apr 11th, 2014 2:00PM