Avalanche Forecast

Issued: Nov 28th, 2012 9:33AM

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

jlammers, Avalanche Canada

South Columbia.

Summary

Confidence

Fair - Timing or intensity of solar radiation is uncertain

Weather Forecast

Moderate snowfall is expected to start Wednesday evening and extend throughout the forecast period. Locally heavy accumulations may exist.Ridgetop winds are forecast to be moderate to strong from the southwest on Thursday trending to strong and southwesterly on Friday and Saturday.Freezing levels should stay at about 1350m for the entire period.

Avalanche Summary

No recent avalanche activity to report. We welcome all field observations at forecaster@avalanche.ca.

Snowpack Summary

Healthy amounts of snow fell throughout last week; however, the more recent break in the weather has given the upper snowpack a chance to settle and gain strength. Over the last few days surface hoar may have been forming, and steep solar aspects may have gone through a melt-freeze cycle creating a sun crust. These newly formed surfaces will be something to watch as the next system moves in to the region on Thursday. Deeper in the snowpack you might find a thin, spotty surface hoar layer between 50 and 85 cm down. As well, the November rain crust now exists over 100cm down in most locations (at treeline and above) and may exist in combination with facets. These layers seem to have been unreactive in recent days, but may have the potential to 'wake-up' with additional loading.The snowpack depth in the alpine ranges from 130-225 cm. Treeline near 150 cm.

Problems

Storm Slabs

Forecast snow and wind will create reactive new wind/storm slabs. Watch for triggering below ridgecrests, in gullies and behind terrain features.

Use extra caution during periods of heavy loading from new snow and wind.>

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

Elevations: Alpine, Treeline.

Likelihood

Very Likely

Expected Size

1 - 4

Persistent Slabs

Although reactivity has been limited, persistent layers represent a low probability-high consequence scenario. These layers may wake-up with additional loading.

Choose well supported terrain without convexities.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Unlikely - Possible

Expected Size

2 - 5

Valid until: Nov 29th, 2012 2:00PM