Avalanche Forecast

Issued: Mar 8th, 2012 8:37AM

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

ccampbell, Avalanche Canada

Northwest Coastal.

Summary

Confidence

Good

Weather Forecast

Friday: Precipitation is expected to taper off to scattered light to moderate showers under an unstable airmass, however strong southwesterly winds are expected to continue. Freezing levels are expected to hover around 500-700 m. Saturday and Sunday: A fairly weak system is expected to arrive on the north coast on Saturday bringing light to moderate precipitation to the area. This system will be through by Sunday but moderate showers will likely prevail under a very unstable airmass. Strong southerly winds and freezing level around 500-1000m are expected for both days.

Avalanche Summary

Observations were limited on Wednesday, but reports suggest that a large natural avalanche cycle occurred in the Stewart and Bear Pass area, but the storm had yet to reach areas further south.

Snowpack Summary

Strong westerly winds are keeping wind slabs fresh and weak on lee aspects and isolated afternoon down flow (katabatic) winds were reported to have deposited new wind slabs primarily in gully features and on northerly aspects. The early February persistent weak layers seem to be bonding, but remain a concern at higher elevations with heavy triggers such as cornice falls. While below treeline persistent slabs are reactive to human triggers on isolated sheltered steep terrain where buried surface hoar is preserved. Surface hoar buried at the beginning of March remains unreactive due to limited slab formation.

Problems

Wind Slabs

Recent variable winds have deposited fresh wind slabs in unusual places, but generally lurking below ridgecrests, behind terrain features and in gullies. Heavy loading is expected to cause large natural avalanches.

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

Elevations: All elevations.

Likelihood

Likely - Very Likely

Expected Size

1 - 6

Storm Slabs

Any new snow is expected to initially bond poorly, and deeper weaknesses within and under recent storm snow are expected to be overloaded.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Likely

Expected Size

1 - 4

Persistent Slabs

Heavy loading is expected reinvigorate early-February persistent weaknesses, and any avalanche failing on these layers are expected to be highly destructive.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Likely

Expected Size

2 - 8

Valid until: Mar 9th, 2012 8:00AM