Avalanche Forecast

Issued: Nov 20th, 2011 9:00AM

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

triley, Avalanche Canada

Northwest Coastal.

This bulletin is based on limited data. Local variation in conditions and danger levels are likely to exist. To produce more accurate forecasts, we need information. Please send an email to forecaster@avalanche.ca

Summary

Confidence

Poor - Timing, track, or intensity of incoming weather is uncertain

Weather Forecast

Moderate to heavy precipitation is forecast to combine with strong winds from the southwest on Sunday night and into Monday. The freezing level is expected to rise to 1000-1200 metres on Monday and Tuesday. Moderate precipitation and moderate southwest winds are expected to continue for Tuesday and Wednesday. The precipitation is forecast to be confined to the coast. Inland areas around Smithers may be quite a bit drier and less windy.

Avalanche Summary

No new avalanches observed. We suspect that the new storm will create new wind-slabs and possibly a new storm slab above the surface hoar that was observed on Saturday.

Snowpack Summary

Varying temperature, precipitation intensity, and wind throughout the recent storms have probably resulted in weaknesses strewn throughout the top metre or so. However, the relatively warm post-storm temperatures on Thursday should favor settlement and strengthening. The mid and lower snowpack is generally well settled and strong, with an old rain crust near the ground. Strong outflow winds from the east may build new wind-slabs on westerly aspects in areas that have snow available for transport. New surface hoar was observed in the Shames area on Saturday. The new snow on Saturday night came with very little wind effect and may have preserved the recent surface hoar.

Problems

Wind Slabs

New storm snow combined with southwest winds may create new wind-slabs.

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

Elevations: Alpine, Treeline.

Likelihood

Likely

Expected Size

1 - 5

Storm Slabs

In areas that may have developed some new surface hoar over the weekend. The freezing level is uncertain over the next few days, so I have extended this problem to all elevations.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible

Expected Size

1 - 4

Valid until: Nov 21st, 2011 8:00AM