Avalanche Forecast

Issued: Dec 5th, 2018 4:00PM

The alpine rating is low, the treeline rating is low, and the below treeline rating is low. Known problems include Deep Persistent Slabs and Wind Slabs.

Aaron Beardmore, Parks Canada

Banff Yoho Kootenay.

By definition the danger is low but there have been isolated skier remote avalanches in steep alpine terrain over the past several days. Conditions are good but its not open season. Also, be watchful for wind-slabs in high elevation lees.

Summary

Weather Forecast

It continues. Cool/cold temperatures will persist Thurs/Fri with no precipitation in sight. There is a chance some precip will track through the region on Saturday but amounts are uncertain and will likely vary. Wind will also increase at that time from the south west.

Snowpack Summary

Nil precip in last 24 hours. 5-10 cm of recent snow has been redistributed into thin wind slabs in immediate lee areas at treeline and above. The October 26th crust/facet layer is ~30 cm above ground. Snow depths range from 50-85 cm at 2000 m. In many areas the entire snowpack is faceting and becoming quite weak.

Avalanche Summary

Another skier accidental was reported today on the slopes skiers left of Bow Summit. It was a size 1.5 and likely failed on the Oct 26th crust. Additionally some small thin windslabs were reported in the Observation Peak area.

Confidence

Due to the quality of field observations on Wednesday

Problems

Deep Persistent Slabs

It is still possible to trigger this layer but it will be in isolated, steep spots and often adjacent to thin rocky areas. Be cautious in steep terrain where a stiffer, more cohesive slab exists over the weak faceted snow at the base of the snowpack.

Whumpfing is direct evidence of a buried instability.

Aspects: All aspects.

Elevations: Alpine.

Likelihood

Unlikely - Possible

Expected Size

1.5 - 2

Wind Slabs

Some light wind transport on Tuesday has created small thin wind slabs in lee areas at higher elevation. They appear to be reactive to ski cutting but are very thin and small.

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

Elevations: Alpine.

Likelihood

Unlikely - Possible

Expected Size

1 - 1.5

Valid until: Dec 6th, 2018 4:00PM