Avalanche Forecast

Issued: Mar 2nd, 2014 7:48AM

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

triley, Avalanche Canada

Sea To Sky.

New snow and wind are developing a new storm slab that may not bond well to the old surface of crusts and facetted crystals. Check out the forecaster blog for more information on the persistent weak layer.

Summary

Confidence

Fair - Forecast snowfall amounts are uncertain

Weather Forecast

Overnight and Monday: Light snow overnight combined with moderate Southwest winds and freezing levels around 500 metres. Snow becoming moderate to heavy in the morning bringing 10-15 cm combined with strong Southwest winds during the day. The freezing level is expected to climb up to about 1200 metres.Tuesday: Snow ending by morning as the freezing level slides back down to about 500 metres. Expect strong Southwest winds.Wednesday: The next pulse of moisture should start during the day. Expect strong Southwest winds combined with the snow.

Avalanche Summary

No new reports of avalanche activity since the cold air moved into the region. Forecast new snow and wind may create a storm slab by morning.

Snowpack Summary

Cold dry new snow has started to bury the recently formed melt-freeze crusts and surface facets that developed over the last few cold days. The melt-freeze crusts were found on all aspects at treeline and below, and on all but North aspects in the alpine. The very warm alpine temperatures and strong solar radiation from last week caused a great deal of settlement in the old storm slab above the early February weak layer. The February weak layer of crusts and facets has been reported to be rounding and bonding in areas where the old storm slab is 150 cm or deeper. Shallow snow pack areas where the old storm slab is closer to a metre or less continue to give sudden planar shears in snow profile tests. North aspects in the alpine may have had enough warming to settle the storm snow into a cohesive slab, but not enough to improve the weak layer bond. Big un-supported alpine North aspects are the most likely place to find a well preserved deeply buried February weak layer that may continue to allow for long propagations resulting in very large avalanches.

Problems

Storm Slabs

Forecast new snow and wind are expected to develop a new storm slab that may not bond well to the mix of old surfaces.

Avoid freshly wind loaded features.>Minimize exposure during periods of heavy loading from new snow, wind.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible - Likely

Expected Size

1 - 3

Persistent Slabs

North aspects in the alpine are the most likely slopes for human triggering the February weak layer. Avalanches releasing on this deeply buried persistent weak layer my be large and destructive.

Stick to simple terrain and be aware of what is above you at all times.>Use conservative route selection, stick to moderate angled terrain with low consequence.>

Aspects: North, North East, East.

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

3 - 5

Valid until: Mar 3rd, 2014 2:00PM