Avalanche Forecast

Issued: Feb 26th, 2013 9:44AM

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.

jfloyer, Avalanche Canada

Cariboos.

Difficult and dangerous conditions remain in the backcountry at this time. Choose cautious and conservative routes.

Summary

Confidence

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

Weather Forecast

Synopsis: Mostly dry until Friday, when a Pineapple Express to the south of the region will spill some moisture over into this region.Wednesday and Thursday: Mostly dry both days. Freezing level around 1200 m. Winds southwest, mostly light, increasing to strong on Thursday afternoon.Friday: Moderate snow, with rain at lower elevations, starting late in the day. Freezing level around 1600 m. Southwesterly ridgetop winds to 80 km/h.

Avalanche Summary

There were reports of avalanches up to size 3 on Monday afternoon. Human triggered avalanches up to size 1.5 were also reported on steep, or unsupported slopes on north-facing slopes. A cornice collapse (size 2.5) was also observed Monday that entrained a lot of loose snow but did not result in a slab avalanche.

Snowpack Summary

40-70 cm of new snow has fallen in the past few days. Strong west-southwest winds have redistributed the new snow into deep wind slabs on exposed lee slopes and cross-loaded gully features. The February 12 persistent weak layer (crust, and/or surface hoar) is now down 60-80 cm and is primed for triggering. Recent snowpack tests have shown easy to moderate "pops" results on this interface and has been particularly touchy on south aspects where a sun crust exists. Deeper persistent weak layers from early February and late January continue to show planar failures when moderate to hard forces are applied in snow pack tests. These deeper layers have not been reactive to the weight of a rider, but they may be triggered by large loads like an avalanche in motion (step-down avalanche), or a cornice fall.

Problems

Persistent Slabs

Additional loading from snow and wind, or the weight of a rider could be enough to trigger the February 12 persistent weak layer.

Be aware of the potential for large, deep avalanches due to the presence of buried surface hoar.>Avoid open slopes and convex rolls at all elevations where buried surface hoar may be preserved.>Avoid open slopes with any steepness over 40 degrees.>Whumpfing, shooting cracks and recent avalanches are all strong indicators of an unstable snowpack.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Likely

Expected Size

2 - 6

Wind Slabs

Expect deep and dense wind slabs in exposed lee and cross-loaded terrain. Also, cornices have grown large and weak and may fail with additional growth or during periods of sunny weather.

Avoid freshly wind loaded features.>Highmark or enter your line well below ridge crests to avoid wind loaded pillows.>Avoid cross loaded features.>

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

Elevations: Alpine, Treeline.

Likelihood

Likely

Expected Size

1 - 5

Valid until: Feb 27th, 2013 2:00PM