Avalanche Forecast

Issued: Mar 14th, 2017 3:14PM

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

triley, Avalanche Canada

Lizard-Flathead.

High freezing levels overnight with continued stormy weather will keep avalanche danger elevated.

Summary

Confidence

Moderate - Freezing levels are uncertain

Weather Forecast

Overnight: Freezing level remaining above 2000 metres, combined with strong southwest winds, and 5-10 mm of precipitation. Wednesday: Freezing level around 2000 metres, combined with moderate-strong southwest winds, and 5-10 mm of precipitation. Thursday: Freezing levels dropping down to at least 1500 metres, moderate southwest winds, and a chance of sunny periods. Friday: Freezing down to valley bottoms, light southwest winds, and mostly sunny with strong solar radiation.

Avalanche Summary

Natural avalanches up to size 2.0 were reported on Tuesday. Observations were limited by poor visibility and travel conditions.

Snowpack Summary

A warm wet storm will form fresh slabs at higher elevations while rain will fall below treeline. Strong winds will load lee features and continue to grow large cornices on alpine ridges. March has delivered regular storms with roughly 80-120 cm of snow sitting above crust and facet interfaces from February. Little is known about the distribution and reactivity of these interfaces. Isolated basal facets still exist in shallow snowpack areas and can produce destructive full-depth avalanches. Possible triggers for these deeper weak layers include cornice falls, rapid warming, or strong solar radiation.

Problems

Storm Slabs

Storm slabs are expected to continue to develop due to forecast new snow and wind. Loose wet avalanches may be a problem at lower elevations.

Stick to non-avalanche terrain or small features with limited consequence.Good day to make conservative terrain choices.Minimize exposure to avalanche terrain during periods of heavy loading from new snow, wind, or rain.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Likely

Expected Size

1 - 2

Deep Persistent Slabs

Storm loading and warming may increase the likelihood of triggering large deep persistent slab avalanches. Concerns include basal facets in alpine terrain and a variety of crust and facet interfaces about a metre deep.

Be aware of the potential for large, deep avalanches.If triggered the storm slabs may step down to deeper layers resulting in large avalanches.Pay attention to overhead hazards like cornices which could easily trigger deep slabs.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

2 - 4

Cornices

Cornices are huge and are ripe for triggering with the warm weather. Cornice falls may trigger larger persistent slab avalanches.

Extra caution needed around cornices with current conditions.Minimize exposure to overhead hazard from cornices.Even small cornice falls may trigger larger avalanches.

Aspects: North, North East, East, South East, South.

Elevations: Alpine.

Likelihood

Likely

Expected Size

1 - 2

Valid until: Mar 15th, 2017 2:00PM