Avalanche forecast

North Columbia

Mar 1, 2018Avalanche Canada
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Archived · expired 9 years ago

Avalanche danger

Fri
Sat
Alpine
3 · Considerable
Treeline
2 · Moderate
Below
2 · Moderate
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Highlights

Storm slabs on steep slopes, wind slabs on lee slopes, and a persistent slab that seems to be "waking up" on southerly slopes. There's lots to think about, and manage!

Avalanche problems

  • Wind Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Likely
    Size
    1.5–2.5
    Shifting wind means wind slabs on many aspects and in unusual places (aka reverse loading). With 40 to 60 cm of recent snow, steep slopes and convex rolls in wind sheltered areas may have "Storm Slabs". Still, wind protected areas are your best bet.

  • 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

Low pressure off the coast is drifting south, which sets the stage for colder drier Alberta air to slide south into the forecast region.THURSDAY: Flurries or light snow. Light to Moderate east or southeast wind. Treeline temperatures around -5 to -10 CFRIDAY: Flurries or light snow. Light northeast winds. Temperatures around -5 to -10 C.SATURDAY: Similar to Friday but a few degrees cooler.

Avalanche Summary

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.

Confidence

Moderate - Wind effect is extremely variable

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 low probability - high consequence avalanche problems. I'm 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