Avalanche Forecast

Issued: Mar 15th, 2017 3:29PM

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

triley, Avalanche Canada

Northwest Coastal.

Freezing levels are expected to drop down to near valley bottoms overnight. Some very low elevation terrain may continue to release as loose wet avalanches.

Summary

Confidence

Moderate - Freezing levels are uncertain on Thursday

Weather Forecast

Overnight: Freezing level dropping down to near valley bottoms, 5-8 cm of new snow, moderate southwest winds. Thursday: Daytime freezing level up to about 500 metres, 10-20 cm of new snow, moderate southwest winds. Friday: Daytime freezing level around 400 metres, 5-8 cm of new snow, light-moderate southwest winds. Saturday: Daytime freezing level around 400 metres, flurries or periods of light snow, moderate southwest winds.

Avalanche Summary

Widespread natural avalanche cycle reported on Tuesday. Natural wet slab avalanches up to size 2.5 and loose wet avalanches up to size 1.5. Reports have been limited due to poor visibility and travel conditions.

Snowpack Summary

Storm slabs continue to develop above 1100 metres. These storm slabs are deep 30-60 cm, with much deeper areas where the wind has transported the snow. Below 1100 metres the snow is moist or wet. The overall results will be widespread touchy storm slabs at higher elevations and unstable wet snow at lower elevations. The storm snow is also stressing a weak interface from February composed of facets, crust, and surface hoar buried over a metre deep. Given the recent activity on this layer before the storm, it should be very reactive during this storm.

Problems

Storm Slabs

Storm slabs are expected to continue to develop with each pulse of new snow and wind.

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

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Likely - Very Likely

Expected Size

2 - 3

Persistent Slabs

The natural storm slab cycle is expected to release persistent slab avalanches. Cornice falls may trigger deeply buried persistent weak layers.

Avoid all avalanche terrain.Be aware of the potential for full depth avalanches due to deeply buried weak layers.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Likely

Expected Size

2 - 4

Wet Slabs

Heavy rain on snow may trigger wet slab or loose wet avalanches at lower elevations. This problem may be short lived due to the forecast cooling trend.

If triggered the loose wet sluffs may step down to deeper layers resulting in large avalanches.Use extra caution on slopes if the snow is moist or wet.

Aspects: All aspects.

Elevations: Alpine.

Likelihood

Possible

Expected Size

1 - 3

Valid until: Mar 16th, 2017 2:00PM