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Avalanche Forecast

Archived

Jan 29th, 2021–Jan 30th, 2021

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

Regions

Sea To Sky.

Green light conditions are in the rearview mirror. Expect widespread new surface instabilities that increase in line with local snowfall amounts and tune in to signs of instability at all elevations. A recently buried weak layer could reach a critical depth on Saturday.

Confidence

Moderate - Forecast snowfall amounts are uncertain.

Weather Forecast

FRIDAY NIGHT: Cloudy with flurries bringing 5-10 cm of new snow. Moderate south winds, increasing into the morning.

SATURDAY: Cloudy with flurries bringing 10-15 cm of new snow, increasing overnight. Strong south winds. Alpine high temperatures around -7.

SUNDAY: Cloudy with continuing snowfall bringing 10-15 cm, with 2-day snow totals reaching 40-50 cm, continuing but easing overnight. Moderate south winds. Alpine high temperatures around -6.

MONDAY: Mainly cloudy with isolated flurries and a trace of new snow. Light variable winds. Alpine high temperatures around -9.

Avalanche Summary

Recent avalanche activity has been limited, following a pattern of human and explosives triggered small (size 1) releases; wind slabs where wind loading has occurred and loose dry where it hasn't.

Looking forward, expect progressively touchy conditions and increasing hazard over the coming days with forecast new snow and wind. Along with the usual surface instabilities, concern for a recently buried weak layer is also rising in step with this active weather.

Snowpack Summary

15-25 cm of new snow, favouring the south of the region, is expected to accumulate by the end of the day on Saturday. This will add to 10-20 cm of recent snow sitting on firm, wind affected snow at upper elevations, on surface hoar in sheltered areas, on a melt-freeze crust below 1900 m, and on a sun crust on south-facing slopes. Recent winds have redistributed much of this new snow, creating wind slabs in leeward terrain, and stripping the new snow off of some windward slopes.

A crust from early December may be found around 200 cm deep in the snowpack. In shallow rocky areas, recent test results suggest that it may still be possible to trigger this layer. In deeper snowpack areas it has shown no recent results and appears to be unreactive in these areas.

Terrain and Travel

  • Storm slab size and sensitivity to triggering will likely increase through the day.
  • Watch for newly formed and reactive wind slabs as you transition into wind affected terrain.
  • Be aware of the potential for loose avalanches in steep terrain where snow hasn't formed a slab.
  • Pay attention to cornices and give them a wide berth when traveling on or below ridges.

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.