Avalanche forecast

North Columbia

Mar 3, 2018Avalanche Canada
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Archived · expired 9 years ago

Avalanche danger

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

Recent new snow and wind in the alpine and at treeline. The sun packs a punch at this time of year - steep south facing slopes are suspect right now.

Avalanche problems

  • Wind Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    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

Confidence

Moderate - Forecast snowfall amounts are uncertain on Saturday

Weather Forecast

SATURDAY: Cloudy with isolated flurries / Light east wind / Alpine temperature -9 SUNDAY: Mix of sun, cloud and isolated flurries / Light west wind / Alpine temperature -11  MONDAY: Mix of sun, cloud and isolated flurries / Light to moderate west wind / Alpine temperature -12

Avalanche Summary

Reports of avalanche activity on Thursday include natural storm and wind slab avalanches to size 2 on northerly and easterly aspects from below tree line into the alpine. There were also a few size 1 skier triggered avalanches reported between 1400 and 2000m. These were primarily on southerly aspects.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.

Snowpack Summary

40 to 60 cm of recent storm snow has been 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.

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