Avalanche Forecast

Issued: Mar 18th, 2014 9:26AM

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

bcorrigan, Avalanche Canada

Sea To Sky.

Summary

Confidence

Fair - Timing, track, or intensity of incoming weather system is uncertain on Wednesday

Weather Forecast

Synopsis: A low pressure system in the North Pacific continues to feed moisture into BC, the next wave should arrive late Tuesday evening.Tonight: Cloudy with flurries, trace of precipitation, freezing level around 1000 metres, winds from the south moderate occasionally gusting to strong.Wednesday: Cloudy with flurries, 10 to 15cm of precipitation expected, freezing level around 1100 metres, ridge top winds light from the south west, gusting to moderate.Thursday: Cloudy with sunny periods and flurries, trace amounts of precipitation, freezing level around 900 metres, winds light occasionally gusting to moderate.Friday: Cloudy with flurries, trace of precipitation, freezing level around 900 metres, winds light from the south west.

Avalanche Summary

Reports of surface sluffing in steep terrain, several reports of size 1 skier triggered wind slabs, recent natural avalanche cycle up to size to in the recent storm snow. Moist snow to ridge tops on solar aspects during the day.

Snowpack Summary

Up to 35 cm of recent storm snow 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. Freezing levels have been cycling between valley bottom and 1500-2000m, and low elevation terrain saw significant rain last weekend. The snowpack at lower elevations has been generally stable but wet snow or rain may destabilize the upper layers of the snowpack.

Problems

Storm Slabs

Strong winds and recent snow 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.>Be careful with wind loaded pockets while approaching and climbing ice routes.>

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 19th, 2014 2:00PM