Avalanche forecast

Northwest Coastal

Jan 2 – 3, 2015Avalanche Canada
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Archived · expired 12 years ago

Avalanche danger

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

Conditions may vary significantly from South to North. Be sure to supplement this forecast with your own local observations.

Avalanche problems

  • Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    1–6
    A series of crusts in the upper and middle snowpack may wake up with loading from snow or wind. Surface avalanches in motion have the potential to step down creating large destructive avalanches.

  • Storm Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Likely
    Size
    1–4
    New snow may not bond well to the previous snow surface and could be triggered naturally or by the weight of a rider, especially where fresh dense wind slabs form (exposed northeast to west aspects).

Confidence

Fair - Forecast snowfall amounts are uncertain

Weather Forecast

Synopsis: Light snow, significantly cooler temperatures, and strong outflow winds are expected on Saturday as the Arctic front re-establishes near the coast. Another Pacific low and frontal system should make landfall on Sunday morning bringing moderate snowfall to the Northwest (10-20 cm). Valley outflows may continue but we should also see strong southerly ridge top winds. Light snow continues on Monday with freezing levels remaining at valley bottom.

Avalanche Summary

There were no reports of avalanches on Thursday, but conditions and visibility were likely poor and kept many observers out of the field. Watch for fresh, touchy wind and storm slabs to develop over the next couple days.

Snowpack Summary

Warm air invaded with the storm on New Years Day and brought rain or freezing rain up to at least treeline in southern sections, which may have squashed the surface hoar that was reportedly widespread before New Years. Temperatures cooled later in the day leaving 5-10 cm of new snow at lower elevations and around 20-25 cm at and above treeline. Further north (Bear Pass, Ninginsaw) it's more likely that the surface hoar layer is now buried by 15-20 cm of new snow. Strong W-NW winds have probably created fresh wind slabs in exposed lee terrain. Older hard slabs may also be lurking on South and West aspects from previous outflow winds. The mid December crust can be found down around 40 to 80 cm and is sandwiched with facets and surface hoar. The mid November crust down 70 to 175 is gaining strength but is still reactive in test profiles. It is likely trending towards dormancy.

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