Avalanche forecast

Northwest Coastal

Feb 28, 2017Avalanche Canada
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Archived · expired 10 years ago

Avalanche danger

Tue
Wed
Alpine
3 · Considerable
Treeline
3 · Considerable
Below
2 · Moderate

Highlights

Fresh and reactive storm slabs will build over the forecast period. Rider triggers are likely, especially where buried surface hoar exists or on leeward slopes that have thicker slabs due to wind loading.

Avalanche problems

  • Storm Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Likely
    Size
    1–2
    New storm slabs will build with forecast snow and wind. They may be more reactive on leeward slopes that see deeper deposits due to wind loading. The new storm slabs may also be more reactive in locations where buried surface hoar exists.

Confidence

Moderate - Intensity of incoming weather systems is uncertain

Weather Forecast

A change in the weather pattern is upon us as the upper jet shifts to a westerly flow allowing a series of Pacific frontal systems to track across the Coastal Regions.Tuesday: Snow 10-25 cm with heavier amounts being more coastal. Alpine temperatures near -6 and ridgetop winds moderate-strong from the SW. Wednesday: Cloudy with snow amounts 5-15 cm. Alpine temperatures near -8 and ridgetop winds moderate with strong gusts from the SW.Thursday: Snow amounts  5-15 cm. Alpine temperatures high of -3 accompanied by gusty (90 km/hr) ridgetop winds. Freezing levels rising to 700 m.

Avalanche Summary

On Sunday no new natural avalanche activity was reported, however; several skier triggered wind slabs up to size 1.5 were triggered in alpine elevations.  Changing wind directions and new storm snow will likely develop new wind slabs in the alpine.

Snowpack Summary

A recent addition of up to 10 cm of new snow has not dramatically changed the snowpack structure, but Saturday night's storm buried a new layer of surface hoar which will get buried deeper after tomorrows snowfall. At this time it is unknown how well preserved this surface hoar. A variety of surface conditions exist including isolated wind slabs, pockets of soft snow (15 to 25 cm deep), sun crusts, and surface hoar. A supportive rain crust exists below 1000 m. A layer of surface hoar that was buried on February 10th can be found buried 30 to 60 cm deep at tree line elevations and has been reactive in some recent snowpack tests. Below this layer, the snowpack is generally settled and strong. The exception is shallow snowpack areas around Bear Pass and Ningunsaw where basal facets remain an ongoing concern.

Regions covered