Strong winds and heavy snowfall are expected Monday night. The avalanche danger rises to HIGH Tuesday, with natural and human-triggered avalanches likely.
Mt. Stephen and Mt Bosworth avalanche closure zone is CLOSED Tuesday, December 9th.
Go to: https://www.pc.gc.ca for more details
Heavy snow and strong winds Monday night will likely trigger a loose dry avalanche cycle on steep terrain. Tuesday is not a day to expose yourself to terrain traps or travel in steep gullies.
With 10–30 cm of new snow arriving alongside strong winds, expect rapid loading across the terrain. Storm slabs will form in sheltered areas while widespread wind slabs build in exposed features. Both natural and human-triggered avalanches will become increasingly likely as the storm peaks.
Limited observations were reported on Monday, likely due to poor visibility. Local ski hills noted new wind slab development and were triggering slabs up to size 2 at treeline and above using explosives. A few small natural avalanches were reported adjacent to the ski area boundary in Lake Louise, also involving small wind slabs. The most notable observation today was the STRONG WINDS!
15–25 cm of storm snow has been blown into drifts and wind slabs at treeline and above. These slabs sit on a few buried crusts in the upper 40 cm. Below this, the Nov 13 rain crust is present in the middle of the snowpack, likely serving as a failure plane. Facetting is breaking down these crusts, producing a slowly developing problem. At treeline and below, snow remains generally soft with a supportive mid-pack, but the entire snowpack is weakening.
A cold front will move through the forecast region Monday night, bringing increased precipitation with 10 to 25 cm of snow. Winds will remain elevated through Tuesday. Temperatures will drop throughout the day Tuesday, with lows near –15°C by Tuesday night.
