Avalanche forecast

Northwest Coastal

Apr 16 – 17, 2016Avalanche Canada
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Avalanche danger

Mon
Tue
Alpine
No rating
Treeline
No rating
Below
No rating
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Highlights

Stormy weekend weather means wintery avalanche conditions. A quick shift in mind-set is required Monday when summer sunshine and temperatures arrive.

Avalanche problems

  • Cornices

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    2–5
    New snow and strong southwest wind will help existing trophy sized cornices grow new noses. This may lead to natural cornice failure during the storm and when the sun returns.

  • Storm Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible - Likely
    Size
    1–4
    New storm slabs at high elevations with additional wind slabs on northerly aspects. Storm snow rests on a crust in many locations which could increase the sensitivity to human-triggering.

Weather Forecast

Strong SW flow hitting the region is very "pineapple" like. Freezing levels should remain relatively low (snow as low as 1000m) through mid-day Sunday and a fair amount of precipitation is expected through Sunday in the south (through Monday near Stewart). SUNDAY: Overcast skies, freezing level as low as 1200m in the morning but climbing to near 2000m by evening, 5 to 10 cm of snow, strong south wind. MONDAY: Mix of sun and cloud as the system clears out, precipitation ends, freezing level rises to around 2500 m, strong south winds. Northern areas (e.g. Stewart) still in the storm. TUESDAY: Sunny, dry, even warmer than Monday (freezing level touching 3000m), light southerly wind.

Avalanche Summary

No new observations to report; however, remember that we have very few eyes & ears still in the mountains.

Snowpack Summary

Mod to Strong S'ly winds able to redistribute HS & HST at high elevations, primarily in the northern and inland areas. Cooler temps in "cold zones" have locked up capping crust. HST storm- & wind-slab developing, when warm temps / sun return there will be a new supply for Loose Wet .Snow is falling at elevations above about 1000m. The moderate to strong southerly wind has likely formed fresh wind slabs and created new cornice growth. This storm snow buried a widespread melt-freeze crust thought to exist almost everywhere except possibly high elevation north facing terrain. Any old layers in the midpack or at the ground are dormant for now, and the snowpack may just gracefully melt away. However, these layers have the potential to wake up; the hottest weather of the year is expected in a few days which might test almost forgotten layers.

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