Avalanche Forecast

Issued: Dec 17th, 2024 4:00PM

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

Parks Canada, Avalanche Canada

Glacier.

An intense Pacific storm will crash into Rogers Pass tonight, delivering 30-40cm of snow, warming temps, and strong to extreme winds. Avalanche activity is expected through the night and into Wednesday, necessitating avalanche control.

A visit to your local ski hill to sample the new snow is recommended.

Summary

Confidence

Moderate

Avalanche Summary

Natural activity is expected to ramp up overnight and continue throughout Wed with heavy snow, warming temps, and strong/extreme winds from the West.

Avalanches have the potential to step-down to the Dec 6 surface hoar layer, which would result in large, destructive slides to valley bottom.

Snowpack Summary

Incoming snow, strong/extreme W winds, and rising temps will build a surface storm slab. This lands on variable wind slabs already present in the Alpine and at Treeline.

A persistent weak layer is down 50-70cm. This interface consists of surface hoar in sheltered locations, a sun crust on solar aspects, and continues to produce moderate-hard sudden results in test profiles.

The snowpack's base is comprised of several early-season melt-freeze rain crusts.

Weather Summary

A strong frontal system arrives tonight, bringing heavy snow, rising temps, and strong winds.

Tonight Snow, 20cm, Alp low -7Â°C, mod S winds, Freezing level (FZL) 900m

Wed Snow, 15-20cm, Alp high -3Â°C, mod/gusting extreme W winds, FZL 1500m.

Thurs Cloudy/sunny periods, isolated flurries, trace amounts, Alp high -3Â°C, mod S winds, FZL 1300m

Fri Cloud, scattered flurries, 5cm, Alp high 2Â°C, light S winds, FZL 1700m

Terrain and Travel Advice

Storm slabs in motion may step down to deeper layers resulting in large avalanches.
Look for signs of instability: whumphing, hollow sounds, shooting cracks, and recent avalanches.

Problems

Storm Slabs

An intense, overnight storm will bring 30-40cm of snow, accompanied by strong/extreme W winds and warming temps. A reactive, cohesive storm slab will form with these conditions and will be easily triggered by riders.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Likely - Very Likely

Expected Size

1.5 - 3

Persistent Slabs

60-80cm of snow overlays a layer of surface hoar in sheltered zones, and a sun crust on steep, solar aspects. There has been limited activity on this layer in recent days, but the new load from the incoming storm could re-awaken this problem.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 3

Valid until: Dec 18th, 2024 4:00PM