Lawinenlagebericht

Northwest Inland

Mar 13 – 14, 2017Avalanche Canada
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Archiviert · abgelaufen 10 years ago

Lawinengefahr

Wed
Thu
Hochgebirge
3 · Erheblich
Waldgrenze
3 · Erheblich
Unterhalb
3 · Erheblich

Kernpunkte

Warm weather has opened the door for large avalanches on deep weak layers. It's time to be extra conservative with your terrain choices.

Lawinenprobleme

  • Persistent Slabs

    • Hochgebirge
    • Waldgrenze
    • Unterhalb der Waldgrenze
    Wahrscheinlichkeit
    Possible - Likely
    Größe
    2–3
    A reactive slab has possibly formed above a weak layer of crusts, facets, and surface hoar that formed in February.
  • Storm Slabs

    • Hochgebirge
    • Waldgrenze
    • Unterhalb der Waldgrenze
    Wahrscheinlichkeit
    Likely
    Größe
    1–2
    Another storm pulse will develop thicker storms slabs that will be extra reactive in the lee of exposed terrain.
  • Deep Persistent Slabs

    • Hochgebirge
    • Waldgrenze
    • Unterhalb der Waldgrenze
    Wahrscheinlichkeit
    Unlikely - Possible
    Größe
    2–3
    A lingering weakness at the bottom of the snowpack may reawaken with the load of the new snow and warming. It'll be most reactive in thin rocky start zones and shallow snowpack locations.

Confidence

Moderate - Due to the number and quality of field observations

Weather Forecast

TUESDAY: Another storm with 5-15 cm of new snow, strong southwest winds, freezing level dropping with alpine temperatures around -4 C.WENDESDAY: Lingering flurries with 2-5 cm, moderate southwest winds, alpine temperatures around -8 C.THURSDAY: Scattered clouds with isolated flurries, moderate southwest winds, alpine temperatures around -8 C.

Avalanche Summary

Small avalanches have been reported in wind affected terrain the past few days, including a few naturals up to size 2 and a few size 1-1.5 skier-triggered avalanches. A MIN report from Friday describes a size 1 wind slab avalanche at Hudson Bay Mountain (here).The storm snow is expected to form reactive slabs and has the potential to form a persistent slab above the weak February interface.

Snowpack Summary

Another 5-15 cm and strong winds will continue to build storm slabs after Sunday's storm delivered 15-30 cm. Warm temperatures will make touchy slabs at higher elevations and unstable wet snow at lower elevations. A weak interface that was buried in late February may finally have enough snow above it to form a reactive slab. The interface is composed of facets, crusts, and surface hoar and may be 40-80 cm deep. There's uncertainty about the distribution and reactivity of this interface. The mid-pack is well consolidated and sits above weak sugary snow near the ground. The deeper basal weakness remain a concern in thin rocky start zones and shallow snowpack locations.

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