Avalanche forecast

Banff Yoho Kootenay

Jan 4 – 5, 2019Parks Canada
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Avalanche danger

Sat
Sun
Alpine
5 · Extreme
Treeline
5 · Extreme
Below
4 · High
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Highlights

Time to stay out of avalanche terrain. Weather models predict another 30-75 cm with strong winds, if this storm continues as forecasted through tomorrow the hazard will be into Extreme for Friday.

Avalanche problems

  • Loose Dry

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Very Likely - Certain
    Size
    1–2.5
    Loose snow avalanches are occurring and is very likely to initiate a larger avalanche on the Persistent slab layer described above.

  • Storm Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Very Likely - Certain
    Size
    1.5–3
    Another 30 cm is forecasted for Emerald adding to the 35 cm already received. This will certainly form a touchy slab. Any avalanches initiated here are likely to step down to the deeper Dec. 10th layer.

  • Deep Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Very Likely - Certain
    Size
    2–3.5
    The Dec. 10th layer of facets and surface hoar down 80-160 cm continues to be rapidly loaded by an ongoing intense storm. Any avalanche that initiates almost certainly to step down to this layer and run well into the run outs below treeline.

Weather Forecast

Another 30-70 cm of snow is expected before the storm ends Friday night with the greatest amounts on the Wapta. Most weather models are in agreement. The system is accompanied by warm temperatures & moderate to strong westerly winds = a perfect recipe for large avalanches stepping down into our persistent weak layers!

Snowpack Summary

25-45 cm of storm snow so far with moderate to strong WSW wind is overloading the Dec. 10th weak layer of facets and depth hoar which is down 80-120 cm. In thin snowpack areas, the Dec.10th layer is mixed in with the basal facets and October crust. In thicker areas, it is a distinct layer, with a stronger snowpack below.

Avalanche Summary

Although visibility was obscured today, a wide spread natural avalanche cycle is occurring with avalanches running well into the run out zones with avalanches up to size 3.5. We expect the cycle to continue through Friday with the ongoing storm. Continued wind transport on Saturday will keep the hazard elevated.

Confidence

Regions covered