Avalanche Forecast

Issued: Nov 25th, 2021 4:00PM

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

wlewis, Avalanche Canada

South Columbia.

Strong winds and heavy snowfall have created slabs that are sensitive to triggering. Hazard is greatest in wind affected terrain. Minimize your exposure to avalanche terrain while the snowpack gains strength.

Summary

Confidence

High - We are confident the likelihood of avalanche will increase with the arrival of the forecast weather. Uncertainty is due to the speed, direction, or duration of the wind and its effect on the snowpack.

Weather Forecast

THURSDAY NIGHT: Snow and strong southwest winds continue above 1500m leaving the Columbia's with another 10-20cm overnight (and storm totals ranging from 40-70cm).

FRIDAY: Winds will shift westerly signaling a brief lull in the storm. Snowfall eases into flurries over the day with up to 10cm expected in localised areas. Freezing levels drop from 1500m to valley bottom overnight.

SATURDAY: We return to an active pattern with strong southwest winds and precipitation increasing from midday. Warmer than the last front, freezing levels are expected to rise to 1500-2000m.

SUNDAY: Freezing levels remain elevated with heavy precipitation.

Avalanche Summary

Our snowpack has received a significant amount of wind affected snow over the last 48 hours. Expect a natural avalanche cycle with the additional load received overnight.

The greatest hazard to backcountry users exists in wind loaded terrain features where deeper slabs are sensitive to a human trigger.

Snowpack Summary

40-70cm of storm snow has been redistributed into lee features at alpine and treeline elevations, sitting over last weeks heavily wind affected storm snow.

The mid November crust is now down 60-150cm on all aspects to 2350m with faceting below the crust. The lower snowpack contains several early season crusts which appear well bonded with no recent reactivity.

Snowpack depths exceed 300cm at treeline and alpine elevations, while below 1600m depth decreases rapidly.

Terrain and Travel

Expect slab conditions to change drastically as you move into wind exposed terrain.
Approach lee and cross-loaded slopes with caution.
Back off if you encounter whumpfing, hollow sounds, or shooting cracks.

Problems

Storm Slabs

Expect deeper deposits at ridge crest, on cross-loaded slopes and mid slope terrain features at treeline and alpine elevations. Human triggering is very likely as the snowpack will take time to gain strength from this new load.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Very Likely

Expected Size

1.5 - 3

Valid until: Nov 26th, 2021 4:00PM