Avalanche Forecast

Issued: Apr 9th, 2014 10:45AM

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

ghelgeson, Avalanche Canada

Cariboos.

Summary

Confidence

Fair - Timing, track, or intensity of incoming weather system is uncertain on Friday

Weather Forecast

Synopsis: A series of weak pacific frontal systems pass over the Northern Columbias throughout the forecast period. The result is continuous, albeit light precipitation accompanied by a fair amount of wind for the next few days.Thursday: Freezing Level: 1100m rising to 1600m; Precipitation: 1:2mm - 1:4cm; Wind: Treeline: Moderate, West | Ridgetop: Strong, NWThursday Night: Freezing Level: 1500m; Precipitation: 2:9mm - 2:15cm;Friday: Freezing Level: 1500m rising to 1700m; Precipitation: 1:7mm - 1:10cm; Wind: Treeline: Moderate, W | Ridgetop: Strong, W/NWSaturday: Freezing Level: Valley Bottom rising to 1600m; Precipitation: Trace; Wind: Treeline: Light, NW | Ridgetop: Moderate, NW

Avalanche Summary

In two separate incidents, natural cornice fall on 38 - 40 (degree), NE facing features around 2400m, initiated size 3 avalanches that failed on the mid-February crust/facet/surface hoar combo with crowns up to 120cm in depth. A natural avalanche with a 45cm crown on a NE facing feature at 2500m was also reported.

Snowpack Summary

Warm temperatures resulted in the freezing level rising to almost 2000m early this week. This has helped to settle out last weeks storm snow at and below treeline, but winter conditions prevail at upper elevations. Strong winds out of both the SW and NW have recently distributed dry snow in the alpine into wind slabs that remain sensitive to human triggering.Three persistent weak layers exist in the highly variable snowpack of the Cariboos: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 150 - 200cm. 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.

Problems

Wind Slabs

Wind slabs immediately lee of ridge crest and mid slope features like ribs remain sensitive to human triggering. Keep an eye on overhead cornices too, you don't want to be underneath or on top of one when it releases.

Be careful with wind loaded pockets, especially near ridge crests and roll-overs.>Give cornices a wide berth when travelling on or below ridges.>

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

Elevations: Alpine.

Likelihood

Possible - Likely

Expected Size

1 - 3

Deep Persistent Slabs

A bomber spring snowpack is still a few weeks away. For now, 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 wake the sleeping giant.

Be aware of the potential for very large, deep and destructive avalanches due to the presence of deeply buried persistent weak layers.>Avoid sun exposed slopes when the solar radiation is strong, especially if snow is moist or wet.>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 10th, 2014 2:00PM