Avalanche Forecast

Issued: Mar 13th, 2013 11:34AM

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

ghelgeson, Avalanche Canada

Northwest Coastal.

Summary

Confidence

Fair - Timing, track, or intensity of incoming weather is uncertain for the entire period

Weather Forecast

Thursday: Continued moist precipitation. 10 -15mm/15-25cm expected over the south portion of the region, very little precip expected in the north. Freezing Level: 200m. Wind: Strong, South.Friday: Occasional light showers/flurries. 10mm/10-20cm expected. Freezing Level 300m. Wind Strong, South.Saturday: A weak pulse of moisture makes its way inland. 5mm water expected. Freezing level tops out around 700m in the afternoon lowering to the surface by Saturday night. Wind: Light, SW

Avalanche Summary

Reports from Tuesday include human and naturally triggered avalanches to size 2 on a variety of aspects. In most of these avalanches the March 9th Surface Hoar/Facet/Crust combo is to blame.

Snowpack Summary

20 - 40cm of unconsolidated new snow is bonding poorly a variety of old surfaces which include: a crust at lower elevations and on solar aspects; old wind slabs in exposed areas, and fairly widespread large surface hoar. Moderate to locally extreme west/southwest winds have redistributed the new snow into soft and hard wind slabs in exposed terrain. This new snow is currently reactive to human triggers primarily where cohesive wind slabs have formed, but reactivity is expected to become more widespread as the overlying slab develops with continued loading. The mid snowpack layers are generally well settled and strong. Facets at the base of the snowpack may resurface as a concern now that spring warming is on the doorstep and full-depth releases are becoming more likely (primarily in the northern part of the region).

Problems

Wind Slabs

Light snow and strong winds have created new wind slabs in exposed terrain. Wind slabs may be particularly reactive in areas where they overlie a weak layer of buried surface hoar and or crusts.

Avoid freshly wind loaded features.>Choose conservative lines and watch for clues of instability.>Avoid exposure to terrain traps where the consequences of a small avalanche could be serious.>Avoid open slopes and convex rolls at and below treeline where buried surface hoar may be preserved.>

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

Elevations: Alpine, Treeline.

Likelihood

Likely

Expected Size

1 - 5

Valid until: Mar 14th, 2013 2:00PM