Avalanche Forecast

Issued: Dec 7th, 2017 3:45PM

The alpine rating is moderate, the treeline rating is moderate, and the below treeline rating is low. Known problems include Wind Slabs and Loose Wet.

cgarritty, Avalanche Canada

Lizard-Flathead.

Sunshine and warming are the critical factors for avalanche danger right now. Be aware of danger increasing in sync with solar radiation and temperature.

Summary

Confidence

Moderate -

Weather Forecast

Friday: Sunny with valley cloud due to lingering temperature inversion. Light west winds. Freezing level to 3300 metres with alpine temperatures of +5. Cooler at lower elevations.Saturday: Mainly sunny with valley cloud due to lingering temperature inversion. Light west winds. Freezing level to 3200 metres with alpine temperatures of +4. Cooler at lower elevations.Sunday: A mix of sun and cloud Light to moderate west winds. Freezing level to 3300 metres with alpine temperatures of +6. Cooler at lower elevations.

Avalanche Summary

Reports from Tuesday included several observations of wind slabs releasing to Size 2 in the Fernie area. These were mainly triggered with explosives but one Size 1.5 slab did release with skier traffic. Looking forward, we should see a gradually diminishing potential for wind slab releases as warm daytime temperatures and overnight cooling promote bonding in the upper snowpack. Please submit your observations to the Mountain Information Network (MIN).

Snowpack Summary

Solar and temperature crusts are expected to have formed on the surface at higher elevations on Thursday. Below the surface, recent shifting winds redistributed loose snow at higher elevations, crossloading and forming wind slabs on a wide range of aspects at treeline and above. Below this wind effect, roughly 30-60 cm of storm snow now sits above the crust that was buried on November 26. The buried crust is supportive and approximately 30 cm thick. It extends from 1600 m to mountain top elevations on all aspects. The bond of our recent storm snow to this crust is expected to be strengthening and it has produced hard, resistant results in recent snowpack tests. Below this interface, the snowpack is moist to ground. Average snowpack depths at treeline elevations in the region range from 80-120 cm.

Problems

Wind Slabs

A recent wind shift from southwest to north means that wind slabs now exist on a wide range of aspects at higher elevations. Be especially cautious of reverse loaded or cross-loaded slopes that see sun exposure.

Use ridges or ribs to avoid pockets of wind loaded snow.Be careful with wind loaded areas, especially near ridge crests and roll-overs.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1 - 2

Loose Wet

Warm, sun-exposed slopes could continue to produce wet loose avalanches either naturally or with rider triggers on Friday - especially in steeper terrain. This problem may expand to northerly aspects as warming persists.

Be cautious of sluffing in steep terrain, particularly where the debris flows into terrain traps.Minimize exposure to steep, sun exposed slopes when the solar radiation is strong.