Avalanche Forecast

Archived

Nov 29th, 2021–Nov 30th, 2021

Alpine

Widespread avalanches certain.

Treeline

Natural and human triggered avalanches likely.

Below Treeline

Natural and human triggered avalanches likely.

Alpine

Natural and human triggered avalanches likely.

Treeline

Natural and human triggered avalanches likely.

Below Treeline

Natural and human triggered avalanches likely.

Alpine

Natural avalanches possible, human triggered probable.

Treeline

Natural avalanches possible, human triggered probable.

Below Treeline

Natural avalanches unlikely, human triggered possible.

Regions

Northwest Coastal.

It's time to stay away from all avalanche terrain, as avalanches are expected to run full path to valley bottom with the arrival of this third atmospheric river.

Confidence

High - We are confident a natural avalanche cycle will begin shortly after the arrival of the incoming weather.

Weather Forecast

Another atmospheric river has begun impacting the region with heavy precipitation of snow then rain. By midday Tuesday, torrential amounts will have fallen and freezing levels will have climbed up. No relief until later Wednesday.

MONDAY NIGHT: Snow/rain 30-40 cm / Extreme, southwesterly winds / Low of 0 / Freezing level rising to 1000 m.

TUESDAY: Snow/rain; 25-35 cm / Southwesterly winds peaking at 110 km/h/ High of +3 / Freezing level rising to 1600 m.

WEDNESDAY: Snow/rain; 10-15 cm / Strong, southwesterly winds / High of -4 / Freezing level lowering to 800 m.

THURSDAY: Snow/rain; 5-10 cm / Strong, southwesterly winds / High of -8 / Freezing level around 500 m.

Avalanche Summary

Several large natural storm slabs (size 2-3) were reported in the last 24 hours in the alpine as well as some small wet snow avalanches near the rain line. With the incoming next wet warm storm, a large avalanche cycle is expected with many avalanches running full path to below treeline.

Snowpack Summary

Southern portion of region (around Terrace):

Freezing moist snowstorm can be found up to 1400 m. Above, dry snow was redistributed by strong winds on lee features at treeline and above. A prominent crust can be found near the bottom of the snowpack.

Treeline snowpack depths are estimated to be around 200-300 cm.

Northern region (around Bear Pass):

Extreme southerly winds have created thick wind slabs in the alpine. Outflows winds have also impacted the snowpack by cross-loading features at treeline and above.

Below, two weak layers of surface hoar have been reported in sheltered areas, as well as a crust near the bottom of the snowpack.

Terrain and Travel

Avoid the runout zones of avalanche paths. Avalanches could run full path.
Avoid all avalanche terrain during periods of heavy loading from new snow, wind, or rain.

Problems

Storm Slabs

Storm Slab avalanches are the release of a cohesive layer (a slab) of new snow that breaks within new snow or on the old snow surface. Storm-slabs typically last between a few hours and few days (following snowfall). Storm-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.