Avalanche Forecast

Issued: Feb 16th, 2018 5:38PM

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

Avalanche Canada shorton, Avalanche Canada

Heavy snowfall in the southern part of the region will make conditions more dangerous than in the north.

Summary

Confidence

Moderate - Forecast snowfall amounts are uncertain

Weather Forecast

SATURDAY: Moderate snowfall with 15-20 cm throughout the day in the north and 30-40 cm in the south, moderate southwest wind, alpine high temperatures around -8 C in the north and -2 C in the south.SUNDAY: Clearing and cooling with moderate northeast wind and alpine high temperatures around -18 C in the north and -10 in the south.MONDAY: Mostly sunny with light northeast wind and alpine high temperatures around -14 C.

Avalanche Summary

No notable avalanches were reported on Thursday or Friday.Reports from earlier in the week indicate wind slabs were reactive in the northern part of the region, including some small (size 1) skier triggered slabs and some larger (size 2-3) naturally triggered slabs on a range of aspects in alpine terrain (some of which were triggered by cornices).

Snowpack Summary

Southern parts of the region are expecting heavy snowfall on Saturday and forming fresh storm slabs as snow accumulates. Northern parts of the region are getting lighter amounts, so fresh slab development will primarily occur in wind-affected terrain.A few interfaces buried below the most recent snow could potentially support wide propagations in the fresh storm/wind slabs. These include scoured crusty surfaces on south-facing alpine slopes, a melt-freeze crust up to about 1900 m, and old wind slabs on a range of aspects at high elevations. The mid-January crust is now buried beneath 80-150 cm of settled snow and may remain sensitive to large triggers - especially in thinner snowpack areas in the north part of the region. Large, looming cornices exist, they are fragile, and they demand respect. Cornice falls are very effective triggers for avalanches on the slopes below them.

Problems

Storm Slabs

An icon showing Storm Slabs
New snow and wind will form fresh slabs on Saturday, particularly in southern parts of the region where up to 40 cm of new snow is expected. Storm slabs will be extra reactive in wind-affected terrain at higher elevations.
Be cautious as you transition into wind affected terrain.Avoid avalanche terrain during periods of heavy loading from new snow and wind.Stick to simple terrain and be aware of what is above you at all times.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Very Likely

Expected Size

1 - 2.5

Cornices

An icon showing Cornices
Large, looming cornices have formed along ridgelines. They need to be given an extra wide berth from above and below. A large cornice collapse in the north of the region may have the ability to trigger a deeply buried weak layer.
Falling cornices may trigger large avalanches on slopes below.Firm cornices can pull back into flat terrain at ridgetop if they fail.

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

Elevations: Alpine, Treeline.

Likelihood

Unlikely - Possible

Expected Size

1.5 - 3.5

Valid until: Feb 17th, 2018 2:00PM