Lawinenlagebericht

Purcells

Feb 19, 2018Avalanche Canada
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Archiviert · abgelaufen 9 years ago

Lawinengefahr

Tue
Wed
Hochgebirge
3 · Erheblich
Waldgrenze
2 · Mässig
Unterhalb
2 · Mässig
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Kernpunkte

Fresh wind slabs and cornices have formed at higher elevations. Riding preserved powder in sheltered trees is a good option.

Lawinenprobleme

  • Wind Slabs

    • Hochgebirge
    • Waldgrenze
    • Unterhalb der Waldgrenze
    Wahrscheinlichkeit
    Possible - Likely
    Größe
    1–2
    Wind slabs may be especially reactive and slow to gain strength due to a mix of underlying weak surfaces. Watch for new wind slab development and reverse loading due to northwest through northeast winds.

  • Persistent Slabs

    • Hochgebirge
    • Waldgrenze
    • Unterhalb der Waldgrenze
    Wahrscheinlichkeit
    Possible
    Größe
    2–4
    Several troublesome layers exist in the snowpack and may be reactive to large triggers such as a cornice or storm slab release. Human triggering may also be possible in shallow or thin, rocky areas.

Confidence

Moderate - Wind effect is extremely variable

Weather Forecast

Clear and cold for the foreseeable future, with overnight lows near -24 Celsius in some locations. Monday: Mainly sunny with increasing cloud in the afternoon. Tree line temperature around -15 Celsius. Winds light northerly.Tuesday: Cloudy with sunny periods. Tree line temperature around -14 Celsius. Light winds northerly. Wednesday: Cloudy. Tree line temperatures around -14 Celsius. Winds light to moderate westerly.

Avalanche Summary

On Sunday, skiers were able to intentionally trigger small (size 1) wind slab avalanches in immediate down wind (lee) features near ridge crests. See here for an update on conditions near Golden. Although deeper, persistent avalanche activity is becoming less frequent, these avalanches point to the continued reactivity and destructive potential of these layers.

Snowpack Summary

Recent storm snow totals are 15-30 cm with more in the very south of the region near Kimberley, where totals are closer to 50 cm. Moderate south west through north west winds shifted these accumulations into deeper, reactive slabs in wind-exposed terrain. The recent snow sits on a mix of older wind slabs in exposed higher elevation terrain, a sun crust on steep solar aspects and surface hoar on sheltered slopes.Below the snow surface several persistent weak layers make up a troublesome snowpack which is not tolerating recent storm loads. In the top 1-2 m of the snowpack, two surface hoar/ crust layers buried in January can be found. Expect to find one or other of these on all aspects and elevations.Deeper in the snowpack (around 200 cm deep) is a facet/crust/surface hoar layer from December, most prevalent at and below tree line.Near the base of the snowpack is a crust/facet combo, most likely to be triggered from thin spots in the alpine.All of these layers have produced large avalanches recently. The wide distribution and ongoing reactivity of these layers suggests that avoidance through choosing simple terrain is the best strategy.

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