Avalanche Forecast

Issued: Apr 12th, 2014 9:55AM

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

mbender, Avalanche Canada

Purcells.

Summary

Confidence

Fair - Freezing levels are uncertain on Monday

Weather Forecast

Sunday: Mostly clear and sunny. Light northwest winds. Freezing level 1500m.Monday: Mix of sun and cloud. Light west winds. Freezing level 2000-2500m.Tuesday: Cloudy with intermittent flurries. Light west winds. Freezing level 1900-2200m.

Avalanche Summary

Recent reports indicate cornice triggered avalanches to size 2.5. Loose wet natural activity to size 2 on solar aspects.

Snowpack Summary

Warm temperatures resulted in the freezing level reaching to almost 2400m early this week in the southern Purcells, around 1800m in the north. This has helped to settle out last weeks storm snow, it's reported to be bonding well to the old surface. Strong winds out of both the SW and NW have redistributed the dry snow still exists at upper treeline and alpine elevations into wind slabs.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

Possible - 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 careful with wind loaded pockets, especially near ridge crests and roll-overs.>Be cautious as you transition into wind affected terrain.>

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

Elevations: Alpine, Treeline.

Likelihood

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.

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

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Unlikely - Possible

Expected Size

4 - 8

Valid until: Apr 13th, 2014 2:00PM