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Avalanche Forecast

Archived

Feb 22nd, 2021–Feb 23rd, 2021

Alpine
Natural avalanches possible, human triggered probable.
Treeline
Natural avalanches unlikely, human triggered possible.
Below Treeline
Natural avalanches unlikely.
Alpine
Natural avalanches unlikely, human triggered possible.
Treeline
Natural avalanches unlikely, human triggered possible.
Below Treeline
Natural avalanches unlikely.
Alpine
Natural avalanches possible, human triggered probable.
Treeline
Natural avalanches unlikely, human triggered possible.
Below Treeline
Natural avalanches unlikely.

Regions

Sea To Sky.

Human triggered avalanches remain a concern at upper elevations where recent snow has accumulated, especially in wind-affected terrain.

Confidence

Moderate - Recent weather patterns have resulted in a high degree of snowpack variability within the region.

Weather Forecast

Lingering flurries continue until Tuesday afternoon.

MONDAY NIGHT: Cloudy with isolated flurries and up to 5 cm of snow, moderate west wind, treeline temperatures drop to -8 C.

TUESDAY: Some isolated flurries in the morning then clearing in the afternoon, moderate northwest wind at ridgetops, treeline temperatures around -6 C.

WEDNESDAY: Mostly sunny, light southwest wind, treeline temperatures around -6 C.

THURSDAY: Flurries with 5-15 cm of snow, strong southwest wind, treeline temperatures around -4 C.

Avalanche Summary

Sunday night's storm resulted in a natural avalanche cycle, with storm slabs up to size 2.5 on wind loaded features. Explosive control on Monday produced several size 2 avalanches (roughly 50 cm thick). On Sunday, during the early stages of the storm, there were several reports of size 1-1.5 human triggered storm slab avalanches (10-25 cm thick). Looking forward, strong wind has likely left reactive slabs at upper elevations.

Snowpack Summary

The weekend's storm delivered 30 cm to the Whistler area and up to 60 cm in deeper areas further west and south. Alpine terrain is likely heavily wind-affected, while a rain crust will form below 1300 m. This snow buried a layer of surface hoar and crusts, but the snow is expected to bond quickly to these layers. The lower snowpack has become strong and bonded.

Terrain and Travel

  • Avoid freshly wind loaded terrain features.
  • Don't be too cavalier with decision making, storm slabs may remain sensitive to human triggering.
  • Investigate the bond of the recent snow before committing to your line.

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.