Avalanche forecast

North Columbia

Mar 2, 2018Avalanche Canada
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Avalanche danger

Sat
Sun
Alpine
2 · Moderate
Treeline
2 · Moderate
Below
2 · Moderate
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Highlights

Think wind slabs on lee slopes and a persistent slab that seems to be "waking up" on southerly slopes.

Avalanche problems

  • Wind Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Likely
    Size
    1.5–2.5
    Shifting wind means there may be old buried wind slabs in places you don't expect them i.e. reverse loading, however the most recent wind has been slowing from a southerly direction.

  • Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    1.5–2.5
    An interface buried up to 70cm deep has "woken-up" with recent snow loading, and a few large avalanches have been triggered easily. Observations have been limited, but this problem seems most reactive in south-facing terrain where buried crusts exist

Weather Forecast

FRIDAY: Cloudy with isolated flurries / Light southeast wind / Alpine temperature -7 / Freezing level 1000m SATURDAY:  Cloudy with isolated flurries / Light southeast wind / Alpine temperature -8 / Freezing level 900m SUNDAY: Mix of sun and cloud / Light southeast wind / Alpine temperature -12 / Freezing level 500m

Confidence

Moderate - Freezing levels are uncertain on Friday

Avalanche Summary

On Wednesday a size 2 remotely triggered (from a distance of 10m) persistent slab avalanche was reported to run on surface hoar sitting on a crust that was buried mid February. This was on a southwest aspect at 1800m. Other recent avalanche activity has consisted of mainly wind slabs and loose dry in the size 1-1.5 range but up to size 2. These were either naturally occurring or intentionally triggered. More interesting avalanches included a re-loaded bed surface where an avalanche previously released on the Nov crust and the "newly awoken" Feb 14 crust found on solar aspects. Deep persistent avalanche activity has become less frequent over the past week.

Snowpack Summary

Around 40 to 60 cm of recent storm snow is being redistributed into deeper, reactive slabs in wind-exposed terrain. Below this is a layer buried mid-February that presents as a sun crust on solar aspects, and spotty surface hoar on sheltered slopes. This layer looks most concerning on on solar aspects where it's associated with with small facets or surface hoar above.There are several deeper layers in the mid-pack that have shown signs of improving but remain on the radar as having a low probability of triggering yet a high consequence avalanche if they are triggered. We're talking about surface hoar layer buried back in December and January. Near the base of the snowpack is a November crust combined with loose sugary snow. These layers may "wake-up" with strong inputs such as sustained warming, sustained snowfall, large triggers (e.g. cornice fall, smaller avalanches coming down from above); human triggering is also possible in shallow snowpack areas with variable snow depth and convoluted terrain.

Regions covered