Avalanche Forecast

Issued: Feb 17th, 2015 8:30AM

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

ccampbell, Avalanche Canada

South Rockies.

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Summary

Confidence

Good

Weather Forecast

Mainly sunny and dry for Wednesday with some cloud cover and possible flurries expected for Thursday and especially Friday. Above freezing alpine temperatures are expected on Wednesday; however, freezing levels should drop back down to 1700 m for Thursday and 1500 m Friday, and valley bottoms overnight throughout the forecast period. Light southwesterly winds are expected to pick up to moderate throughout the day on Wednesday, before decreasing to light on Thursday and shifting to northwesterlies on Friday.

Avalanche Summary

No new avalanches reported.

Snowpack Summary

A thick supportive crust has frozen on the surface at lower elevations, with a trace amount of fresh snow on top in some places. Two weak crusts in the snowpack remain a concern for persistent slabs and step-down avalanches. One buried mid-January was recently found down 70 cm and and the other buried mid-December was found down 135 cm at treeline where the total depth was 200 cm.

Problems

Wind Slabs

Hard wind slabs may be lurking below ridge crests and in exposed gullies. These locally deep deposits can fracture over surprising distances above trigger points and into low-angled terrain, often catching people by surprise.

Be aware of the potential for wide propagations due to the presence of hard windslabs.>Be cautious as you transition into wind affected terrain.>Be careful with wind loaded pockets, especially near ridge crests and roll-overs.>

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

Elevations: Alpine, Treeline.

Likelihood

Unlikely - Possible

Expected Size

1 - 4

Cornices

Not only a hazards in themselves, cornice falls can also act as heavy triggers for persistent slab avalanches on the the slope below.

Cornices become weak with daytime heating, so travel early on exposed slopes.>Give cornices a wide berth when travelling on or below ridges.>

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

Elevations: Alpine.

Likelihood

Unlikely - Possible

Expected Size

1 - 3

Deep Persistent Slabs

Although unlikely, these highly destructive avalanches remain possible with heavy impacts (e.g. cornice falls and surface avalanche stepping down) in the right spot (e.g. thin rocky areas). Daytime warming will also increase sensitivity.

If your sled is bogging down, don?t spin the track and trigger the weak layer below.>Avoid steep convexities or areas with a thin or variable snowpack.>Be aware of the potential for very large, deep avalanches due to the presence of buried surface hoar or a facet/crust layer.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Unlikely - Possible

Expected Size

3 - 5

Valid until: Feb 18th, 2015 2:00PM