Avalanche Forecast

Issued: Mar 2nd, 2017 5:10PM

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

Avalanche Canada swerner, Avalanche Canada

Forecast snow, wind and rising temperatures are driving the danger rating to HIGH.

Summary

Confidence

Moderate - Timing, track, or intensity of incoming weather system is uncertain

Weather Forecast

Friday: Snow amounts 10-20cm by Friday afternoon. Ridgetop winds moderate from the SW. Alpine temperatures near -4 and freezing levels rising to 1500 m by the afternoon. Saturday: Snow amounts 5-10 cm. Confidence remains low in actual snow amounts and timing. Rigetop winds gusting to 75 km/hr from the SW. Alpine temperatures near -5 and freezing levels 1300 m. Sunday: Unsettled conditions continue with snow 5-10 cm. Ridgetop winds generally light from the SW and freezing levels falling to 1000 m.

Avalanche Summary

On Thursday, a size 2.5 deep persistent slab avalanche was reported from the Elkford- North riding. It looked to be 24 hrs old and likely failed earlier in the storm. It did fail within the basal facets and scrubbed down to rocks. Widespread loose dry avalanches were also noted from steep terrain features up to size 1.5. Natural avalanche activity will likely continue with warming temperatures, forecast snow and strong winds.

Snowpack Summary

Another 17 cm of low density storm snow arrived overnight bringing the recent snow totals up to 67 cm in the past week. The new snow will likely have a poor bond to previous old snow surfaces that consist of stiff wind slabs, crusts and facets. Strong southwesterly winds is redistributing the new snow onto leeward slopes, building thicker and stiffer slabs. The mid-pack in this region is generally well settled and strong, but the bottom third of the snowpack is composed of weak facets (sugary snow crystals). Approximately 100-120 cm of settled snow sits above the weak layer of sugary, rotten facets that developed mid- December. This remains a concern and should be on your radar especially when change is happening to the snowpack.

Problems

Storm Slabs

An icon showing Storm Slabs
Touchy storm slabs have a poor bond to old snow surfaces and are primed to rider triggering. Thicker and stiffer slabs will exist on leeward slopes due to wind transported snow.
Avoid avalanche terrain during periods of heavy loading from new snow, wind.Recent wind loading have created wind slabs on leeward (northerly- easterly) slopes.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Likely - Very Likely

Expected Size

1 - 2

Deep Persistent Slabs

An icon showing Deep Persistent Slabs
A weak layer near the base of the snowpack has the potential for large avalanches, especially in areas with minimal rider compaction or thin variable snow cover.
Pay attention to overhead hazards like cornices which could easily trigger the deep persistent slab.Be aware of the potential for full depth avalanches due to weak layers at the base of the snowpack.Avoid steep convexities or areas with a thin or variable snowpack.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Unlikely - Possible

Expected Size

2 - 4

Valid until: Mar 3rd, 2017 2:00PM