Avalanche Forecast

Issued: Dec 20th, 2017 3:51PM

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

jmcbride, Avalanche Canada

South Coast.

On the North Shore the new snow has been showing signs of poor bonding to the recent crust surface. Further north in alpine terrain watch for fresh wind slabs on lee-loaded and cross-loaded slopes.

Summary

Confidence

High - The weather pattern is stable

Weather Forecast

THURSDAY: Mainly cloudy, flurries. Accumulation 5-10 cm. Ridge wind light to moderate from the west. Temperature -3. Freezing level 500 m. FRIDAY: Mix of sun and cloud, light flurries. Accumulation trace. Ridge wind light from the north. Temperature -3. Freezing level 500 m.SATURDAY: Mostly sunny. Ridge wind light from the east. Temperature -6. Freezing level surface.

Avalanche Summary

On Tuesday a few natural, loose dry avalanches were observed in the recent storm snow. Ski cutting also produced storm slab and loose dry avalanches to Size 1 running far on the December 18th crust. And explosive control work produced storm slab avalanches up to Size 1.5, propagating about 40 m wide with crowns 20-25 cm deep, failing on the December 18th crust.

Snowpack Summary

Since Monday, the region has received 20-30 cm of storm snow on top of the most recent December 18th melt-freeze crust which formed following Sunday's rain event to upper elevations. Below this crusts lies 20 cm of wet snow which appears to be well bonded to the lower December 16th crust. Below this second crust the snowpack is well settled to ground. Snowpack depths are about 125 cm at 1100 m elevation, with many early season hazards present at lower elevations.

Problems

Wind Slabs

Tuesday's storm snow is now being redistributed by wind at upper treeline and alpine elevations and lies on a widespread melt-freeze crust that has been showing poor signs of bonding.

Use caution in down wind (lee) areas. Wind loading may create pockets of wind slab.Watch for signs of instability such as whumpfing, or cracking.

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

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 2

Loose Dry

Storm snow has been showing signs of poor bonding to the most recent crust.

Be cautious of sluffing in steep terrain, particularly where the debris flows into terrain traps.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible

Expected Size

1 - 2

Valid until: Dec 21st, 2017 2:00PM