Avalanche Forecast

Issued: Mar 20th, 2016 8:44AM

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

jlammers, Avalanche Canada

Northwest Coastal.

Extra caution is needed in areas in the northern part of the region where buried persistent weaknesses remain active.

Summary

Confidence

Moderate - Intensity of incoming weather systems is uncertain on Monday

Weather Forecast

10-15cm of new snow is expected to fall between Sunday night and Monday afternoon. A mix of sun and cloud is forecast for Tuesday while another 5-10cm of snow is possible on Wednesday. Ridgetop winds should be light to moderate and easterly on Monday, light on Tuesday, and moderate and southerly on Wednesday. The freezing level should sit at about 1300m for the forecast period.

Avalanche Summary

On Saturday a natural cornice fall triggered a size 2.5 slab in northeast facing alpine terrain. Although observations were limited due to weather, the slab is thought to have failed on a crust from late February. No other recent avalanches have been reported.

Snowpack Summary

A dusting of new snow overlies wind slabs in exposed high elevation terrain and settled dry (and faceting) powder on shaded and sheltered slopes. Lower elevations and south aspects have been going through daily melt-freeze cycles. In these areas, new accumulations likely overlie a crust or moist snow. A layer of surface hoar or melt-freeze crust buried on March 3 is down 70-100cm and has been recently reactive in the areas north of Stewart. An older crust/facet layer buried in early February can now be found down over a meter but this layer has been dormant for several weeks.

Problems

Cornices

Natural cornice releases remain an ongoing concern for professionals in the region. Recently, falling cornices have also triggered large avalanches on the slope below.

Extra caution needed around cornices with current conditions.>

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

Elevations: Alpine.

Likelihood

Possible

Expected Size

2 - 5

Wind Slabs

New snow and wind on Monday may form fresh wind slabs in higher elevation lee terrain. New snow accumulations will also be hiding older wind slabs.

Be cautious as you transition into wind affected terrain. >The recent snow may now be hiding windslabs that were easily visible before the snow fell.>

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

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1 - 3

Persistent Slabs

Persistent weaknesses have recently been reacting to cornice triggers in the northern part of the region. Keep these in mind if you're riding near Bear Pass or Ningunsaw Pass.

Be aware of the potential for large, deep avalanches due to the presence of buried surface hoar. >Dig down to find and test weak layers before committing to a big slope. >

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Unlikely - Possible

Expected Size

3 - 6

Valid until: Mar 21st, 2016 2:00PM