Avalanche forecast

Northwest Inland

Mar 15 – 16, 2017Avalanche Canada
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Avalanche danger

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

Storm slabs continue to develop with each pulse of new snow and wind.

Avalanche problems

  • Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Unlikely - Possible
    Size
    2–3
    A reactive slab has possibly formed above a weak layer of crusts, facets, and surface hoar that formed in February. This weak layer may be spotty and confined to terrain that is sheltered from the wind.

  • Storm Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Likely
    Size
    1–2
    Storm slabs are expected to continue to develop due to forecast new snow and wind. Watch for the transition to moist or wet snow as you descend in elevation.

  • Deep Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Unlikely - Possible
    Size
    2–3
    A lingering weakness at the bottom of the snowpack may reawaken with the load of the new snow and warming. It'll be most reactive in thin rocky start zones and shallow snowpack locations.

Weather Forecast

Overnight: Freezing level down to valley bottoms, 2-3 cm of new snow, moderate southwest winds. Thursday: Daytime freezing level around 700 metres, 3-5 cm of new snow, moderate southwest winds, and a chance of sunny periods in the afternoon. Friday: Daytime freezing level around 500 metres, 2-3 cm of new snow, moderate southwest winds. Saturday: Daytime freezing level around 500 metres, 3-5 cm of new snow, moderate southwest winds.

Avalanche Summary

Numerous natural avalanches up to size 2.5 were reported from the west of the region in the Howson's on Tuesday. Natural avalanches up to size 2.0 were reported from the Hankin area on Monday.

Confidence

Moderate - Forecast snowfall amounts are uncertain

Snowpack Summary

Storm slabs continue to build with each pulse of snow and wind. Warm temperatures will make touchy slabs at higher elevations and unstable wet snow at lower elevations. A weak interface that was buried in late February may finally have enough snow above it to form a reactive slab. The interface is composed of facets, crusts, and surface hoar and may be 40-60 cm deep. There's uncertainty about the distribution and reactivity of this interface. The mid-pack is well consolidated and sits above weak sugary snow near the ground. The deeper basal weakness remains a concern in thin rocky start zones and shallow snowpack locations.

Regions covered