Avalanche forecast

Sea To Sky

Nov 30 – Dec 1, 2018Avalanche Canada
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Avalanche danger

Sun
Mon
Alpine
2 · Moderate
Treeline
1 · Low
Below
1 · Low
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Highlights

Avalanche danger ratings have decreased, but cornices and wind slabs likely remain problematic in the alpine, especially in extreme terrain. We're working from very few observations right now, please let us know what you're seeing on the MIN!

Avalanche problems

  • Wind Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    1–2
    Soft slabs up to 30 cm in depth exist in the alpine. Cooling temperatures continue to reduce the slabs sensitivity to human triggering, but you need to be mindful of this problem, especially in extreme terrain and immediately lee of ridgecrest.

  • Cornices

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    1–2
    Touchy cornices have formed on many alpine ridgelines. These cornices may be large and weak. Do not trust them and avoid travel on or underneath them.

Confidence

Low - Due to the number of field observations

Weather Forecast

We are  transitioning into a period of pronounced high pressure. The forecast period is marked by cooler temps, clearing skies and no significant precipitation, even in the extended forecast.FRIDAY NIGHT: Freezing level around 800 m, very light variable wind, a trace of snow possible. SATURDAY: A few clouds, freezing level around 800 m, light northeast wind, no significant precipitation expected.SUNDAY: A few clouds, freezing level around 800 m, light northeast wind, no significant precipitation expected.MONDAY: Clear skies, freezing level around 800 m, light east/northeast wind, no significant precipitation expected.

Avalanche Summary

No new avalanche activity reported on Thursday.  On Wednesday cornices were touchy, a size 1.5 cornice failure was initiated with a very light load. Control work produced storm slabs that averaged size 1.5 on a variety of aspects in the alpine. The outlier was a size 3 avalanche induced by control work on a south facing alpine feature which stepped down to the early November crust.Skies cleared Tuesday allowing some observation of avalanches that likely released at the height of the storm. A large (size 2.5) avalanche was reported on a northeast facing glacial feature between 2100 and 2200 m. The avalanche failed naturally with a crown up to 1 meter in depth. Another large natural avalanche (size 2) was reported from a north facing feature near 2000 m. Several natural loose wet avalanches to size 1.5 were also reported from treeline.Please submit any observations you have to the Mountain Information Network here,

Snowpack Summary

Monday and Tuesday's intense precipitation event rain-soaked the existing snowpack up to about 1800 m and left 20 to 30 cm of wet snow in place up to 2000 m. Above 2000 m the storm produced around 60 cm of new snow. The upper 20 to 30 cm of snow is reportedly dry in the alpine. Strong to extreme wind on Monday and Tuesday formed storm slabs, cornices, and wind damaged snow in high elevation alpine terrain. Above 2000 m, 50 to 200 cm of snow now sits on the early November melt-freeze crust. Little is known about the reactivity of this interface in the alpine. This crust may be associated with weak faceted crystals in some places where it lies close to the ground. This is most likely to cause problems in glaciated terrain or on smoother, high elevation slopes where the summer snow did not melt out.

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