Avalanche Forecast

Issued: Mar 15th, 2017 4:11PM

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 and continued rain will keep the avalanche danger elevated. The weather forecast is a tricky mix of changing freezing levels and uncertain precipitation amounts.

Summary

Confidence

Moderate - Freezing levels are uncertain on Thursday

Weather Forecast

Overnight: Freezing level at 2000 metres, slowly dropping by morning to 1200 metres. Expect 15-20 mm of precipitation that will be mostly rain, except at the highest elevations. Thursday: Daytime freezing level around 1500 metres, 5-10 cm of new snow above 1500 metres, moderate southwest winds. Friday: Overnight freezing down to valley bottoms, and then rising back up above 2000 metres. Mostly sunny with valley fog in the morning, and light southwest winds. Saturday: Freezing level remaining above 2000 metres, strong southwest winds, and 5-10 mm of precipitation.

Avalanche Summary

Widespread natural avalanches were reported up to size 3.0. Most of these were reported to be loose wet avalanches gouging and entraining mass as they travelled down the path. This avalanche cycle is likely to continue overnight,

Snowpack Summary

Heavy rain to mountain tops has soaked the upper snowpack and caused rapid settlement of the recent storm snow. The surface has been reported to be wet to at least 1800 metres, and moist to 2000 metres or higher. The forecast brief drop in freezing levels in the early morning may not have much effect on the snowpack when the daytime warmth brings the freezing level back up. 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 at the highest alpine elevations due to forecast new snow and wind. Loose wet avalanches may continue to release at all elevations due to the rain and high freezing levels.

Stick to non-avalanche terrain or small features with limited consequence.Avoid all avalanche terrain during periods of heavy loading from new snow, wind, or rain.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Likely - Very Likely

Expected Size

2 - 3

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.

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

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.

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

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

Elevations: Alpine.

Likelihood

Very Likely

Expected Size

1 - 3

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