Avalanche Forecast

Issued: Feb 26th, 2014 8:27AM

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.

rbuhler, Avalanche Canada

South Rockies.

Summary

Confidence

Fair

Weather Forecast

High pressure conditions are expected for Thursday before a weak system from the southwest affects the region Thursday night and Friday. On Friday night, cold arctic air will push into the region and will dominate on Saturday.Thursday: A mix of sun and cloud, temperature inversion conditions, ridgetop winds 20-30 W-NWThurs. night/Friday: Mostly cloudy, snow flurries 4-8cm, treeline temperature around -12C, ridgetop winds 10-20 W-NWSaturday: Mostly sunny, treeline temperature around -20C, ridgetop winds 20-30 NE-E

Avalanche Summary

On Tuesday, we received reports of several natural size 1 loose dry avalanches from steeper terrain features, most likely triggered by the sun. Also reported was a size 2 wind slab triggered by explosives near Fernie. Check out the South Rockies Blog for recent photos and insights of what people are seeing out there.

Snowpack Summary

Large cornices loom on ridgelines and threaten the slopes below. Variable winds have transported some of the recent storm snow, building new wind slabs on leeward slopes. A persistent slab 80-120 cm thick sits on a weak interface comprising of facets and a crust. It continues to show sudden planar shears at the interface, and a high degree of sensitivity to human triggers. Wide propagations and remote triggering remain a concern. With forecast sunny periods, solar aspects may see moist snow surfaces which will then form a crust overnight. The 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 like a cornice fall or large avalanche.

Problems

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

Possible - Likely

Expected Size

3 - 6

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.

Extra caution needed around cornices with current conditions.>Avoid freshly wind loaded features.>

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

Elevations: All elevations.

Likelihood

Likely

Expected Size

1 - 4

Valid until: Feb 27th, 2014 2:00PM