Avalanche Forecast

Issued: Mar 20th, 2016 8:53AM

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

jlammers, Avalanche Canada

Northwest Inland.

Continue to approach large alpine slopes with caution, especially with cornices perched above.

Summary

Confidence

Moderate - Wind speed and direction is uncertain on Monday

Weather Forecast

5-15cm 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

No new avalanches have been reported.

Snowpack Summary

In some areas, 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 from early March can be found down 60-80cm but only seems to be a problem for the northern half of the region. Professional operators are still tracking two deep weak layers from early-January and early-February which can be found down about 1m or more. These layers have been dormant for a couple weeks but could wake up with heavy storm loading, substantial warming, or a heavy trigger like a cornice fall. In the far north of the region, there is an isolated weakness at the base of the snowpack that has been responsible for some very large and destructive avalanches.

Problems

Wind Slabs

New snow and wind on Monday may form fresh wind slabs in exposed lee terrain. New snow will also hide older wind slabs.

Be cautious as you transition into wind affected terrain.>Use ridges or ribs to avoid pockets of wind loaded snow.>The recent snow may now be hiding windslabs that were easily visible before the snow fell.>

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

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 3

Cornices

Cornices are reported to be large and weak. A falling cornice could also trigger a large slab on the slope below.

Cornices become weak with daytime heating. >Extra caution needed around cornices with current conditions.>

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

Elevations: Alpine.

Likelihood

Possible

Expected Size

2 - 5

Deep Persistent Slabs

Three buried weaknesses remain a concern, mainly in the north of the region (see snowpack discussion for details). Isolated very large avalanches remain a possibility, especially with a heavy trigger like a falling cornice.

Be aware of thin areas that may propagate to deeper instabilities. >Be aware of the potential for full depth avalanches due to deeply buried weak layers. >

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Unlikely - Possible

Expected Size

3 - 6

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