Avalanche Forecast

Issued: Feb 23rd, 2021 4:00PM

The alpine rating is considerable, the treeline rating is considerable, and the below treeline rating is considerable. Known problems include Storm Slabs.

Avalanche Canada mconlan, Avalanche Canada

The next storm starts impacting the region Tuesday afternoon. Danger remains elevated as slabs from both the previous storm and incoming storm will likely be triggerable by riders.

Summary

Confidence

High -

Weather Forecast

TUESDAY NIGHT: Clear skies, 30 km/h northwest wind, alpine temperature -9 C.

WEDNESDAY: Increasing clouds with afternoon snowfall, accumulation 5 to 10 cm, 60 to 90 km/h southwest wind, alpine temperature -6 C.

THURSDAY: Cloudy with snowfall, accumulation 30 to 50 cm, 80 km/h west wind, alpine temperature -6 C.

FRIDAY: Cloudy with snowfall, accumulation 10 to 20 cm, 40 to 60 km/h northwest wind, alpine temperature -8 C.

Avalanche Summary

A natural avalanche cycle was reported across most of the region during the intense stormy conditions on Sunday and Monday. The avalanches were mostly large (size 2 to 3) and found at all elevation bands. This MIN shows excellent photos of slab avalanches around treeline elevations, potentially releasing on the surface hoar described in the Snowpack Summary.

Looking towards Wednesday, natural avalanche activity is expected to taper but human-triggered avalanches will remain likely to be triggerable by riders in avalanche terrain.

Snowpack Summary

Over 100 cm of snow fell on the weekend above around 800 m, which formed reactive storm slabs. Another 20 to 30 cm of snow fell to near valley-bottom on Monday and Tuesday. Wind slabs were formed in exposed terrain at treeline and alpine elevations from strong southwest wind. All of this snow may not bond well to previous surfaces buried mid-February, which may include:

  • Hard wind-affected snow, particularly in exposed alpine and treeline terrain,
  • Weak and feathery surface hoar in sheltered areas, with the most suspect elevation bands being lower alpine, treeline, and within openings below treeline,
  • A 20 to 40 cm thick layer of sugary faceted grains that developed during cold periods, and/or
  • A hard melt-freeze crust below treeline.

The mid-pack has been reported as being well-settled. There are presently no deeper concerns.

Terrain and Travel

  • Choose conservative terrain and watch for clues of instability.
  • Watch for newly formed and reactive wind slabs as you transition into wind affected terrain.
  • Give the new snow several days to settle and stabilize before pushing into bigger terrain.
  • Potential for wide propagation exists, fresh slabs may rest on surface hoar, facets and/or crust.
  • Pay attention to cornices and give them a wide berth when traveling on or below ridges.

Problems

Storm Slabs

An icon showing Storm Slabs

Over 100 cm of snow has accumulated across much of the region, falling with strong south to west wind. Storm and wind slabs will likely remain touchy to human traffic on Wednesday, particularly where the snow overlies weak surface hoar and/or faceted grains. The next storm will start impacting the region Wednesday afternoon, bringing more snow and strong to extreme southwest wind.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Likely

Expected Size

1.5 - 2.5

Valid until: Feb 24th, 2021 4:00PM