Avalanche Forecast

Archived

Nov 22nd, 2019–Nov 23rd, 2019

Alpine

Natural avalanches possible, human triggered probable.

Treeline

Natural avalanches unlikely.

Below Treeline

Natural avalanches unlikely.

Alpine

Natural avalanches unlikely, human triggered possible.

Treeline

Natural avalanches unlikely.

Below Treeline

Natural avalanches unlikely.

Alpine

Natural avalanches unlikely.

Treeline

Natural avalanches unlikely.

Below Treeline

Natural avalanches unlikely.

Regions

Northwest Inland.

Saturday's storm is expected to pack a bit of a punch in the alpine with a combo of substantial new snow amounts, strong winds, and rising freezing levels. Slabs that form as a result are unlikely to bond well to the current snow surface.

Confidence

Moderate - Forecast snowfall amounts are uncertain.

Weather Forecast

Friday night: Cloudy with flurries bringing 5-10 cm of new snow. Light rain below about 1300 metres. Strong southwest winds.

Saturday: Cloudy with a second storm pulse bringing 15-20 cm of new snow. Light to moderate southwest winds. Alpine high temperatures rising from around -3 to 0 with freezing levels rising from 1000 to 1700 metres over the day.

Sunday: A mix of sun and cloud with isolated flurries and a trace of new snow. Moderate west winds. Alpine high temperatures around -6.

Monday: A mix of sun and cloud. Light to moderate west winds. Alpine high temperatures around -8.

Avalanche Summary

For this weekend, the focus is on new snow accumulating above the current snow surface. This new snow is expected to shed easily once sufficient depths accumulate to form new slabs. Strong winds are expected to accelerate both accumulation and slab formation.

Snowpack Summary

Observations in the region are limited, but we have indications that for most areas where snow cover exists, the snowpack is capped by a supportive melt-freeze crust. Above 1800 metres a light, patchy cover of windblown snow can be found in lee areas and small windloaded pockets.

New snow forecast for Saturday is not expected to bond well to either of these surfaces.

Total snow depths of 30-40 cm have been reported at alpine elevations in the Smithers area, with depths diminishing rapidly with elevation below 1500 metres.

Problems

Wind Slabs

Wind Slab avalanches are the release of a cohesive layer of snow (a slab) formed by the wind. Wind typically transports snow from the upwind sides of terrain features and deposits snow on the downwind side. Wind slabs are often smooth and rounded and sometimes sound hollow, and can range from soft to hard. Wind slabs that form over a persistent weak layer (surface hoar, depth hoar, or near-surface facets) may be termed Persistent Slabs or may develop into Persistent Slabs.