Avalanche Forecast

Issued: Jan 30th, 2016 7:01AM

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

Avalanche Canada pmarshall, Avalanche Canada

Destructive persistent weak layers should still be on your radar if you're heading to the north of the region. Also, keep an eye on new snow amounts and how well this new snow is bonding.

Summary

Confidence

Moderate - Forecast snowfall amounts are uncertain

Weather Forecast

Tonight and Sunday: Periods of snow. 5-10 cm tonight and 10-15 cm on Sunday (snow looks heaviest in the northern part of the region). The freezing level is around 600-900 m. Winds are moderate from the S-SW easing to light. Monday: Cloudy with flurries and clearing. The freezing level is around 500-700 m and winds are light from the SW. Tuesday: Mainly sunny. The freezing level remains near 500 m and winds are light and variable.

Avalanche Summary

On Thursday, slab avalanches to size 3.5 were observed on a variety of aspects and elevations. These occurred in response to heavy storm loading from rain and snow. The mid-January surface hoar was the suspected culprit in many of these avalanches. Of note was a size 4 slab avalanche in Steep Creek in the Duffey Lake area. Moving forward, cooling will likely put a cap on persistent slab avalanche activity, except on higher elevation slopes in the north of the region where reactivity is expected to persist. Forecast wind and snow could create fresh touchy wind slabs in exposed lee and cross-loaded terrain this weekend.

Snowpack Summary

Convective precipitation delivered variable new snow amounts to the region on Friday. In the south, as much as 40 cm of snow may have accumulated, while further north there may have only been 10-15 cm. This new snow likely rests on moist/wet snow or a hard rain crust depending on elevation. A storm earlier in the week created deep and dense storm slabs in high elevation terrain and cause substantial cornice growth. Where it still exists, the mid-January surface hoar layer is between 60 and 130 cm below the surface. The combination of heavy storm loading and warm temperatures has likely flushed out this weak layer in many areas; however, I would still exercise caution on higher elevation slopes in the north of the region where continued reactivity at this destructive interface is likely to persist.

Problems

Persistent Slabs

An icon showing Persistent Slabs
Buried persistent weaknesses may have been destroyed in most areas, but remain cautious in high elevation terrain (particularly in the north of the region) where this problem may be lingering.
Be aware of the potential for large, deep avalanches due to the presence of buried surface hoar.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

3 - 6

Storm Slabs

An icon showing Storm Slabs
New snow may not initially bond well to the previous snow surface, especially in exposed lee terrain where fresh wind slabs develop. Also, watch for loose dry sluffing in steep open terrain. 
Stay off recent wind loaded areas until the slope has had a chance to stabilize.>Avoid freshly wind loaded features.>Be cautious of sluffing in steep terrain.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Likely

Expected Size

1 - 3

Cornices

An icon showing Cornices
Recent stormy weather has encouraged widespread cornice growth. Large cornice falls can be destructive by themselves, but can also be a trigger for surprisingly large avalanches on the slope below.
Give cornices a wide berth when travelling on or below ridges.>

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

Elevations: Alpine.

Likelihood

Possible

Expected Size

1 - 3

Valid until: Jan 31st, 2016 2:00PM