Avalanche Forecast

Issued: Feb 16th, 2017 4:07PM

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

Avalanche Canada cam_c, Avalanche Canada

Be aware of conditions that change with elevation and expect touchy fresh storm and wind slabs at higher elevations.

Summary

Confidence

Moderate - Forecast snowfall amounts are uncertain on Saturday

Weather Forecast

FRIDAY: Unsettled conditions with isolated flurries, moderate becoming light southwesterly winds and freezing levels dropping to 1500 m.SATURDAY: Cloudy with flurries bringing another 5-10 cm overnight, light winds and freezing levels around 1300 m.SUNDAY: Cloudy with light flurries, light southerly winds and freezing levels around 1400 m.

Avalanche Summary

Reports from Wednesday and Thursday morning include continued natural loose wet avalanche activity up to Size 2 at treeline and below. On Tuesday a 70 cm deep by 200 m wide Size 3.5 natural storm slab avalanche was reported that ran 1000 m from a south facing alpine start zone. On Sunday, explosives triggered numerous storm slabs up to size 2.5 as well as two deep persistent slabs up to size 3.5 which released down 200 cm, most likely on the November crust. Touchy new wind slabs are sensitive to light triggers and have the potential to step down and trigger persistent slab avalanches.

Snowpack Summary

Expect to find 15-20 cm of fresh snow blown into touchy wind slabs at higher elevations, and wet and cohesionless rain-soaked snow at lower elevations, which should soon freeze into a solid crust. Rapidly settling storm snow from last week is still bonding poorly to the previous snow surface from early February, which is now down 60-80 cm and includes a sun crust on steep sun-exposed slopes, faceted snow, as well as surface hoar on sheltered open slopes. A persistent weakness buried mid January is now down 80-150 cm and the November crust is down around 200 cm. These deep persistent weaknesses appear to be waking up with the warmer temperatures and several avalanches have recently released up to 2 m deep.

Problems

Persistent Slabs

An icon showing Persistent Slabs
A persistent weakness down 60-80 cm remains remains sensitive to light triggers in isolated areas. Smaller avalanches have the potential to step down to this and deeper persistent weakness resulting very large avalanches.
Be aware of the potential for large avalanches due to the presence of deeply buried weak layers.Whumpfing, shooting cracks and recent avalanches are all strong indicators of unstable snowpack.Use conservative route selection, choose moderate angled and supported terrain with low consequence.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible

Expected Size

3 - 4

Wind Slabs

An icon showing Wind Slabs
Touchy fresh wind slabs are likely lurking below ridgecrests and behind terrain features at higher elevations.
Avoid freshly wind loaded features.Use ridges or ribs to avoid pockets of wind loaded snow.If triggered the wind slabs may step down to deeper layers resulting in large avalanches.

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

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1 - 2

Valid until: Feb 17th, 2017 2:00PM