Avalanche Forecast

Issued: Mar 20th, 2014 9:25AM

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, track, or intensity of incoming weather system is uncertain

Weather Forecast

Synopsis: A northwesterly flow will bring cool and unsettled weather for the next few days .Tonight: Cloudy, trace to 5 cm of precipitation, freezing level at valley bottom, winds light from the south east.Friday: Cloudy, no precipitation in the forecast, freezing level at valley bottom, light south east ridge top winds.Saturday: Cloudy with snow, 5 to 10cm of precipitation, freezing level at valley bottom, ridge top winds, light to moderate from the south east.Sunday: Sunny with cloudy periods, No precipitation in the forecast, freezing level around 600 metres, light ridge top winds from the north.

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

10 to 20cm of overnight snow combined with winds have produced yet another set of wind slabs overlying the storm slabs at tree line and above. The storm slab, however, 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. Moderate to strong SW winds have formed wind slabs on lee slopesBelow the storm snow, the upper 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 storm, 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 steep slopes below cornices.>Avoid exposure to terrain traps where the consequences of a small avalanche could be serious.>Avoid areas with overhead hazard.>

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 quiet recently but may "wake up" with the weight of the new storm snow. Smaller avalanches may step down and trigger one of these deeper layers.

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

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

3 - 6

Valid until: Mar 21st, 2014 2:00PM