Avalanche Forecast

Issued: Nov 15th, 2011 9:27AM

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

pgoddard, Avalanche Canada

Purcells.

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

Summary

Confidence

Poor - Due to limited field observations

Weather Forecast

Skies are briefly clearing ahead of the next band of precipitation, which is due to arrive late on Wednesday. Light snowfall is expected overnight Wednesday and on Thursday morning. Temperatures should remain cool.There is a chance of another pulse of snow arriving on Friday but weather models are showing uncertainty.

Avalanche Summary

A cycle of natural avalanche activity was observed in Quartz Creek on Sunday. Wind slabs (20cm deep) and persistent slabs (60cm deep) were observed. Persistent slabs were propagating widely and running on a weakness towards the base of the snowpack. Observations are limited to the northern Purcells.

Snowpack Summary

There is significant variability in the snowpack across the region. Snowpack depth at treeline varies from around 40-130cm. Up to 50cm of snow fell over the last few days, which was redistributed by strong winds blowing first from the south and then from the north-west. A basal layer of facets was reported in the Dogtooth Range, with a weak interface between the lower facets and recent storm snow. Observations are limited.

Problems

Wind Slabs

Strong southerly, then north-westerly, winds have shifted snow onto downwind slopes.

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

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1 - 4

Storm Slabs

Over the last two days, widespread storm slab activity has been observed. Weak snow at the base of the snowpack is likely to take time to gain strength. Steep or exposed terrain should be treated with suspicion.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 3

Valid until: Nov 16th, 2011 3:00AM