Avalanche Forecast

Issued: Feb 25th, 2014 9:01AM

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.

swerner, Avalanche Canada

South Rockies.

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

Summary

Confidence

Fair - Timing or intensity of solar radiation is uncertain on Wednesday

Weather Forecast

The arctic ridge of high pressure that has been dominating the Interior Regions will start to retreat on Wednesday, bringing warmer alpine temperatures and slightly rising freezing levels. Some disturbances in this flow will bring cloudy skies and light snow later in the forecast period.Wednesday: Sunny and -2.0 degrees expected in the alpine. Ridgetop winds will be light from the NW. Thursday: Cloudy with light snow and -1.0 degrees in the alpine. Ridgetop winds 25 km/hr from the NW. Freezing levels near 1800 m.Friday: Cloudy with isolated flurries. Alpine temperatures -19.0 and ridgetop winds will be light from the NE.

Avalanche Summary

A few loose dry avalanches from steeper terrain were reported on Tuesday. On Saturday, we received a report of a size 3 snowmobile triggered avalanche in the Coal Creek area (Notch). To our knowledge, there were 7 people involved and all were self rescued. The avalanche was on a North aspect and the crown depth was 1-2 m deep. Conditions remain ripe for human triggers.Natural avalanche activity, especially on steep solar aspects will likely spike with full sunshine during the forecast period.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 rider 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.

Use conservative route selection, resist venturing out into complex terrain even if you observe no obvious signs of unstable snow.>Avoid areas with overhead hazard, especially on southerly slopes.>Remote triggering is a concern, watch out for adjacent slopes.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood

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.

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 26th, 2014 2:00PM