Avalanche forecast

Banff Yoho Kootenay

Mar 19 – 20, 2019Parks Canada
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Avalanche danger

Thu
Fri
Alpine
4 · High
Treeline
4 · High
Below
4 · High
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Highlights

http://www.pc.gc.ca/apps/scond/Cond_E.asp?oID=34810&oPark=100092The avalanche cycle continues. With the on-going blast of heat, calm  winds and clear sky conditions, expect the danger to climb to HIGH with daytime heating.

Avalanche problems

  • Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Very Likely
    Size
    1–3
    10-20 cm settled snow (since Mar 7) has formed slabs above treeline due to winds and warm temperatures. They sit over a variety of weaker surfaces. Natural and skier triggering of this recent snow has occurred in the last several days on all aspects.

  • Loose Wet

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Very Likely - Certain
    Size
    1–3
    Rapidly warming daytime temperatures and high solar inputs are causing loose wet avalanches to start by mid morning. Some of these are running long distances or triggering slabs along the way. Avoid exposure to these slopes when they heat up.

  • Deep Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    1–3.5
    We are starting to see places where avalanches are failing on the basal weaknesses and scrubbing to ground. This is mostly occurring with large triggers in thin rocky areas but we expect this type of avalanche activity to increase with more heat.

Weather Forecast

Clear skies again tonight will help freeze the snowpack despite the relatively warm overnight temperatures. Conditions will deteriorate rapidly with another clear and calm day for Wednesday where temperatures at treeline will climb to 10-15C. This diurnal spring like pattern will continue until the weekend.

Snowpack Summary

Sun crusts or moist snow on solar aspects and moist snow at lower elevations. 10-20 cm of recent snow sits over a mix of facets, sun crust and wind slabs above treeline, and over 30-50 cm of weak facets elsewhere. While a supportive mid-pack exists in thicker areas, weak facets to the ground are seen in many thin areas.

Avalanche Summary

A widespread spring avalanche cycle continues with the bulk occurring on solar aspects as they heat up through the day. Avalanche size ranged from size 1-3. Most slides have been within the surface snow (March 7 interface) with some stepping down a bit deeper; however, we have seen only a few avalanche step down to the basal layers.

Confidence

The weather pattern is stable

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