Avalanche Forecast

Issued: Mar 16th, 2014 9:58AM

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

bcorrigan, Avalanche Canada

Sea To Sky.

Summary

Confidence

Fair - Due to the number and quality of field observations

Weather Forecast

Synopsis: A low pressure system in the Gulf of Alaska will feed moisture onto the coast and into the interior for the next 4 or 5 days.Tonight: Cloudy with flurries, trace of precipitation, freezing level at valley bottom, light ridge top winds occasionally gusting to moderate.Monday: Sunny periods with a few clouds, no precipitation in the forecast, freezing level around 800 metres, winds from the west, to 40 Km/hr.Tuesday: Cloudy with flurries, possible 5 to 10 cm of precipitation,, freezing level around 1000 metres winds from the south west, light occasionally gusting to moderate.Wednesday: Sunny with cloudy periods and isolated flurries, possible 10 to 15cm of precipitation,, freezing level around 1100 metres, winds light from the south west, light to moderate.

Avalanche Summary

Limited reports from Saturday suggest avalanche activity was limited to wind loaded features. More widespread storm slab activity is expected for Saturday night and Sunday as the storm passes through.

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 to surface hoar on shady, sheltered slopes. At lower elevations, a melt-freeze (or rain) crust can be expected in most areas. S Moderate to strong SW winds have formed wind slabs on lee slopes. Below 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

Heavy snowfall and strong winds will continue to build storm slabs. Expect to find stiff wind slabs in lee features from recent strong S-SW winds associated with this storm.

Avoid all avalanche terrain during periods of heavy loading from new snow, wind, or rain.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Very 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 17th, 2014 2:00PM