Avalanche Forecast

Issued: Mar 21st, 2014 9:31AM

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

bcorrigan, Avalanche Canada

Sea To Sky.

Spring sun could push the hazard higher than forecast on solar aspects. Keep an eye on cornice hazards

Summary

Confidence

Fair - Timing or intensity of solar radiation is uncertain

Weather Forecast

Synopsis: A weak ridge of high pressure sits over the forecast area and should block out any major precipitation for the next 2 days.Tonight: Clear periods, no precipitation in the forecast, freezing level around 100 metres, winds light, from the north.Saturday: Cloudy with trace a of precipitation, freezing level around 1300 metres, ridge top winds should be light from the south east.Sunday: Cloudy periods, trace of precipitation in the forecast, freezing level around 1800 metres, light ridge top winds from the south west.Monday: Cloudy with flurries, freezing level around 2000 metres, winds light to moderate from the south.

Avalanche Summary

Avalanche activity from yesterday confined to small ( size 1 to 1.5 )soft slabs, wind slabs and some loose wet sluffs in steep south facing terrain. Caution should be exercised on solar aspects as the spring sun begins to heat things up. Cornices are becoming large and mature and deserve serious respect.

Snowpack Summary

Up to 60cm of snow has fallen in parts of the forecast region in the past 7 days. This storm snow combined with winds has continued to produced wind slabs overlying the storm slabs at tree line and above. The storm slab is sitting on a variety of layers. A well developed sun crust has formed on solar aspects and, prior to this storm, surface hoar formed on shady, sheltered slopes. At lower elevations, a melt-freeze (or rain) crust can be expected in most areas. Below the storm snow, the snowpack is generally well settled from the recently warm weather. Two persistent weak layers remain a concern but these problems are becoming more isolated. Before the recent storms, the early-March crust/facet layer was down roughly 1m and the early Feb. layer is down 1.5m or more. These layers are now deep enough that human-triggering is unlikely, but smaller avalanches or cornices failures have the potential to step down to these layers, and,.... cornices are definitely getting larger these days. Lowered freezing levels are good for overnight recovery of the snowpack below 1700 metres. Daytime warming could produce loose, wet avalanches below 1700m especially on steep solar aspects.

Problems

Storm Slabs

Strong winds associated with the recent storms has formed wind slabs on lee slopes, look out for wind loaded pockets. Expect sluffing in steep terrain, especially on steep solar aspects. Cornices are becoming large and mature, give them a wide berth.

Avoid areas with overhead hazard.>Avoid exposure to terrain traps where the consequences of a small avalanche could be serious.>Avoid steep slopes below cornices.>The new snow will require several days to settle and stabilize.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible - Likely

Expected Size

1 - 4

Deep Persistent Slabs

Two deep persistent weak layers continue to be a concern within the snowpack. These have been pretty much dormant lately, but high temperatures or large load like a cornice failure may step down and trigger one of these deeper layers.

Avoid exposure to overhead avalanche terrain, large avalanches may reach the end of run out zones.>Be aware of the potential for large, deep avalanches.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

3 - 6

Valid until: Mar 22nd, 2014 2:00PM