Avalanche Forecast

Issued: Nov 30th, 2014 7:51AM

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

triley, Avalanche Canada

Sea To Sky.

Little change expected in the danger ratings until the next storm.

Summary

Confidence

Poor - Due to the number and quality of field observations

Weather Forecast

Some cloud over night with very little or no precipitation and moderate Southwest winds. Cold overnight temperatures around -15 in the alpine. Clearing during the day Monday with slightly warmer alpine temperatures around -10 combined with moderate Northwest winds. Tuesday mostly clear with alpine temperatures around -5. Some moisture starting to enter the picture by Thursday.

Avalanche Summary

A skier triggered a size 1.0 wind slab near treeline on a convex slope in the Whistler backcountry. No other reports from this region.

Snowpack Summary

Surface hoar and near surface facets are reported to be growing during the cold and clear weather. Strong Northeast outflow winds developed windslabs 10-40 cm deep since Friday. Heavy precipitation gave way to clearing skies and rapidly cooling temperatures early on Friday morning. Most areas saw heavy rain up to at least 2000 m this week. Above this it's possible that dense storm slabs and fresh cornices formed. Where it did rain, the snowpack is probably frozen solid with a dusting of fresh snow on top. The lower elevation snowpack has also thinned significantly. A weak layer of facetted snow on a crust was buried around 50-60 cm deep before the rain. This weakness may have been flushed out or may now be bridged by a solid ice crust; however, there is no new info on this interface so it would be wise to investigate its existence and strength before venturing into bigger terrain.

Problems

Wind Slabs

Snow transported by recent outflow winds may have developed into pockets of windslab that could be triggered by human activity.

Avoid travelling in areas that have been reverse loaded by winds.>Avoid freshly wind loaded features.>Be alert to conditions that change with elevation.>

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

Elevations: Alpine, Treeline.

Likelihood

Unlikely - Possible

Expected Size

1 - 3

Persistent Slabs

The old storm slab may be up to 100 cm thick above the crust that was buried on November 20th. This slab may continue to be triggered in areas in the high alpine where the rain did not get up to the highest elevations before the re-freeze.

Choose well supported terrain without convexities.>

Aspects: All aspects.

Elevations: Alpine.

Likelihood

Unlikely - Possible

Expected Size

1 - 4

Valid until: Dec 1st, 2014 2:00PM