Avalanche Forecast

Issued: Feb 9th, 2017 4:15PM

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

Avalanche Canada cam_c, Avalanche Canada

Conditions are primed for people triggering avalanches, which are expected to be particularly deep and touchy in the southern parts of the region. A Special Avalanche Warning applies to this region. Click here for more details.

Summary

Confidence

High -

Weather Forecast

FRIDAY: Cloudy with scattered flurries bringing approximately 5 cm of fresh snow, moderate to strong southwesterly winds, and freezing level around 1400 m.SATURDAY: A mix of sun and cloud, moderate westerly winds, and freezing levels around 1400 m.SUNDAY: Mainly sunny, light but gusty westerly winds and freezing levels rising to 1600 m.

Avalanche Summary

No new avalanches were reported on Wednesday. Reports from Tuesday include numerous explosives-triggered storm slab avalanches up to Size 2.5, with one Size 1 ski cut. Further evidence of numerous recent natural storm slab avalanches up to Size 2 was also reported. Also, a skier accidentally triggered a 50cm thick Size 2 storm slab avalanche on a southwest aspect at 2200 m.Heavy loading from snow and wind is expected to result in continued natural avalanche activity with touchy storm and wind slabs remaining sensitive to light triggers.

Snowpack Summary

15-25cm of fresh snow, accompanied by moderate winds, adds to the 50-100 cm from the past few days, with the heaviest amounts in the southern part of the region. This recent storm snow is forming deep touchy slabs, especially where it has been wind-loaded, which are bonding poorly to the previous snow surface that includes sun crust on steep sun-exposed slopes, faceted snow, as well as surface hoar on sheltered open slopes. Weaknesses are also lingering within the recent storm snow, with 'upside-down' conditions and several easy to moderate shears being reported. A persistent weakness buried mid January is now down 60-120 cm and consists of buried surface hoar in sheltered areas, sun crust on south aspects, and/or faceted old snow. It has generally stabilized but may be sensitive to triggering in isolated areas where surface hoar is preserved. Another surface hoar/facet weakness buried mid-December found 70-140 cm is generally considered dormant. This and deeper persistent weaknesses remain concerns isolated to shallow snowpack areas where they lie closer to the surface.

Problems

Storm Slabs

An icon showing Storm Slabs
Storm slabs are highly sensitive to light triggers, and especially deep and touchy on wind-loaded slopes. Be aware of the potential for storm slab avalanches to entrain loose snow or even 'step down' to a deeper weak layer.
Be cautious as you transition into wind affected terrain.Watch for signs of instability such as whumpfing, or cracking.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Likely

Expected Size

2 - 3

Persistent Slabs

An icon showing Persistent Slabs
Persistent slab problems may be back in play with the new load that has been added to the snowpack. Stick to supported terrain and exercise extra caution where the new snow has stacked onto a previously shallow snowpack.
Avoid convexities or areas with a thin or variable snowpack.Be aware of the potential for large avalanches due to the presence of deeply buried weak layers.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible

Expected Size

2 - 4

Valid until: Feb 10th, 2017 2:00PM