Avalanche Forecast

Issued: Nov 25th, 2018 4:25PM

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

dsaly, Avalanche Canada

Purcells.

A warm and wet system is moving across the province. Slabs will gain strength with increased winds and rising temperatures. In areas with higher than forecasted snowfall, avalanche hazard may be higher than forecasted.

Summary

Confidence

Low - Intensity of incoming weather systems is uncertain

Weather Forecast

SUNDAY NIGHT: Mainly cloudy with isolated flurries / Precipitation: up to 5 cm / Light south ridge windMONDAY: Cloudy with flurries / Accumulation: 5-10 cm / Alpine temperature: High 0C / Moderate south ridge wind / Freezing level 1500mTUESDAY: Cloudy with flurries / Accumulation: up to 10 cm / Alpine temperature: High +2C / Moderate south-southwest ridge wind / Freezing level 1700mWEDNESDAY: Cloudy with flurries / Accumulation: up to 5 cm / Alpine temperature: High -3 / Light to moderate southwest ridge wind / Freezing level 1500m

Avalanche Summary

On Saturday, a large human triggered avalanche was reported in the South Columbia forecast region. The size 3 avalanche occurred on a steep, north aspect in the alpine and failed to ground, likely on the October crust. Find the MIN report here.Small windslabs have been triggered by skiers and explosives in cross-loaded and lee terrain features at treeline and alpine elevations. Earlier in the month, a natural avalanche cycle took place over the late October crust/facet combination. Be aware of the continued possibility for smaller avalanches to 'step down' or even initiate at this deeper layer.

Snowpack Summary

15-30 cm recent snow has buried a surface hoar/sun crust layer. Reports in the region show this variable layer sitting above a layer of recently reactive wind slab. This wind slab layer overlies yet another widespread layer of surface hoar from mid-November, now found about 20-40 cm deep. A final, prominent feature of the snowpack is a combination of a melt-freeze crust and underlying sugary, faceted snow found around the base of the snowpack. Avalanches have been triggered where there is a slab above this crust.

Problems

Wind Slabs

Recently formed windslabs may react to human triggers. Older, stubborn wind slabs may be buried under more recent snowfall.

Caution in lee and cross-loaded terrain near ridge crests.

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

Elevations: Alpine, Treeline.

Likelihood

Unlikely - Possible

Expected Size

1 - 2.5

Deep Persistent Slabs

A nasty combination of crust and sugary, faceted snow exists at the base of the snowpack in the alpine. This weak layer has already produced large avalanches and may be triggered by the weight of a person.

Travel one person at a time on all slopes capable of producing an avalanche.Use caution in lee areas. Wind slabs may step down to deeper layers resulting in large avalanches.

Aspects: All aspects.

Elevations: Alpine.

Likelihood

Unlikely - Possible

Expected Size

1.5 - 3

Valid until: Nov 26th, 2018 2:00PM