Avalanche Forecast

Issued: Apr 13th, 2014 9:26AM

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

mbender, Avalanche Canada

Purcells.

Summary

Confidence

Good

Weather Forecast

Monday: Mix of sun and cloud. Light west winds. Freezing level 2600m.Tuesday: Cloudy with intermittent flurries. Light gusting to moderate northwest winds. Freezing level 1600m.Wednesday: Cloudy with sunny periods. Intermittent flurries possible. Light west winds. Freezing level 1800m.

Avalanche Summary

Recent reports indicate explosives triggered activity to size 2.5 on primarily east and north aspects. Expect to see continued loose wet natural activity on solar aspects as the sun continues to shine and freezing levels rise on Monday.

Snowpack Summary

Mainly sunny weather and the freezing level reaching up to 2100m has created moist snow and/or a crust on all aspects and elevations except for high elevation north-facing terrain. This has helped to settle out the past week's storm snow accumulations. Moderate west and northwest winds have redistributed what little dry snow still exists at upper elevations into wind slabs immediately lee of ridge crest.Three persistent weak layers exist in the highly variable snowpack of the Purcells:The mid-March sun crust/surface hoar layer down 50-80cm still has potential for human-triggering in isolated areas. The early-March crust/facet/surface hoar layer down around 80-120cm has become less susceptible to human triggering, but still has the capacity to produce large avalanches.The mid-February crust/facet/surface hoar combo is typically down 60 - 120cm. Direct triggering of this layer has become unlikely, however, cornice fall, a smaller avalanche in motion or prolonged warming may wake this layer up, which would result in very large and destructive avalanches.Weak basal facets exist in many areas, but triggering is unlikely.

Problems

Loose Wet

Expect to see an increase in avalanche activity on solar aspects as the sun stays out for extended periods of time.

Avoid sun exposed slopes when the solar radiation is strong, especially if snow is moist or wet.>Give cornices a wide berth when travelling on or below ridges.>

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

Elevations: All elevations.

Likelihood

Likely

Expected Size

1 - 3

Wind Slabs

Wind slabs immediately lee of ridge crest and mid slope features may still be sensitive to human triggering.

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.

Likelihood

Unlikely - Possible

Expected Size

1 - 3

Deep Persistent Slabs

The potential for very large deep slab avalanches needs to remain on your radar. Cornice fall, strong solar, warming temps or a surface avalanche in motion could could act as triggers.

Be aware of the potential for very large, deep and destructive avalanches due to the presence of deeply buried persistent weak layers.>Carefully evaluate big terrain features by digging and testing on adjacent, safe slopes.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Unlikely - Possible

Expected Size

4 - 8

Valid until: Apr 14th, 2014 2:00PM