Avalanche Forecast

Issued: Feb 24th, 2014 8:32AM

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

Avalanche Canada swerner, Avalanche Canada

Don't let the good weather lure you into high risk scenarios. Conditions remain tricky.With clear, sunny skies the avalanche danger will likely increase.

Summary

Confidence

Fair - Timing or intensity of solar radiation is uncertain

Weather Forecast

The strong arctic ridge will continue to push modified arctic air across the region. Clear and dry conditions will persist until Thursday. Some unstable disturbances are embedded in this flow, bringing scattered cloud and light precipitation on Thursday/ FridayTuesday: Sunny. Alpine temperatures -8.0. Ridgetop winds are light from the north..Wednesday: Sunny. Alpine temperatures near -2.0. Ridgetop winds light from the northwest. Freezing levels 1600 m.Thursday: Cloudy with snow amounts near 5 cm. Alpine temperatures near -4.0. Ridgetop winds moderate from the northwest. Freezing levels 1500 m.

Avalanche Summary

On Saturday, we received a report of a snowmobile triggered a size 3 slab avalanche in the Coal Creek area (Notch). It sounds like 7 sledders were involved and all self rescued. The avalanche was on a North aspect and the crown was 1-2 m deep. On Friday, the SR field team witnessed several large snowmobile remote triggered slab avalanches in the Elk Valley North. These avalanches were all triggered below treeline around 1800 m. On Thursday, a natural size 2.5 avalanche occurred near the Coal Creek road. The debris just reached the road, didn't block it but the air blast covered the road with branches.Wind loading and sunshine are forecast, which means natural avalanche activity will likely increase, especially on southerly aspects.Check out the South Rockies Blog to view photos of the remote triggered avalanches that were witnessed on Friday. It displays how sensitive and reactive the persistent weak layer continues to be. Finding safe areas to ride, and choosing the most appropriate terrain is very tricky given the current conditions.

Snowpack Summary

Large cornices loom over slopes and wind slabs are building on leeward aspects. The recent storm snow is up to a metre thick and remains touchy. This slab continues to settle and become more cohesive, overlying a complex medley of persistent weak layers (mainly facets and some surface hoar). The weak layers are widespread on all aspects and at all elevations across the region. This is the classic firm slab over weak layer that allows for wide propagations and remote triggering. This problem may persist for days or even weeks. The mid-pack is strong and supportive. A deep persistent layer of facets and depth hoar near the base of the snowpack has remained dormant to this point, but may become a concern with additional load and stress on the snowpack.

Problems

Persistent Slabs

An icon showing Persistent Slabs
The persistent weak layer continues to be very sensitive to any additional load. Remote triggering from adjacent terrain and very long fracture propagations are a major concern on all aspects and elevations.
Remote triggering is a concern, watch out for adjacent slopes.>Avoid areas with overhead hazard, especially on southerly slopes.>Use conservative route selection, resist venturing out into complex terrain even if you observe no obvious signs of unstable snow.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Likely

Expected Size

3 - 6

Wind Slabs

An icon showing Wind Slabs
Wind has transported snow and built fresh, touchy wind slabs on the leeward side of terrain features. Be aware of weak cornices looming over slopes. If they fail, it could trigger large slab avalanche on the slope below.
Avoid freshly wind loaded features.>Extra caution needed around cornices with current conditions.>

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

Elevations: All elevations.

Likelihood

Likely

Expected Size

1 - 4

Valid until: Feb 25th, 2014 2:00PM

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