Lawinenlagebericht

Purcells

Jan 11 – 12, 2013Avalanche Canada
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Archiviert · abgelaufen 14 years ago

Lawinengefahr

Sun
Mon
Hochgebirge
3 · Erheblich
Waldgrenze
3 · Erheblich
Unterhalb
2 · Mässig
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Kernpunkte

Current avalanche conditions are complex.  Stay very cautious in your approach to the mountains this weekend.

Lawinenprobleme

  • Wind Slabs

    • Hochgebirge
    • Waldgrenze
    • Unterhalb der Waldgrenze
    Wahrscheinlichkeit
    Possible - Likely
    Größe
    2–6
    Previously strong winds formed thick wind slabs that deserve caution and respect.  Wind slabs may be found lower on slopes than you normally see them.

  • Persistent Slabs

    • Hochgebirge
    • Waldgrenze
    • Unterhalb der Waldgrenze
    Wahrscheinlichkeit
    Possible - Likely
    Größe
    1–5
    Storm snow is settling into a cohesive slab 30 - 100 cm in depth.  This slab rests on a mixed bag of weak layers that when triggered may result in large avalanches.

Confidence

Fair - Due to variable snowpack conditions

Weather Forecast

Saturday: Light winds out of northwest.  Freezing level at valley bottom.  No significant snowfall. 1500m temp: -10Sunday: Light ridgetop winds out of the N increasing to moderate NW in the evening. Freezing level at valley bottom.  No significant snowfall.  1500m temp: -10Monday:  Mod/Strong NW winds at ridgetop.  Freezing level at valley bottom.  No significant snowfall.Tuesday: Freezing level rising to 2000m+

Avalanche Summary

Operators report evidence of a mid storm avalanche cycle to size 2.5.  Evidence of the cycle is slowly being eroded by the winds. Explosive work in the region produced avalanches on all aspects that averaged size 2.  Near the Purcell Wilderness Conservancy a cycle was observed that produced avalanches to size 3 in the alpine which ran to valley bottom.  Small avalanches were observed on unsupported treeline features too.

Snowpack Summary

40 - 80 cm of rapidly settling storm snow rests on the January 4th interface which consists of small facets, surface hoar (up to 12mm) in sheltered treeline and below treeline areas and sun crust on steep south and west facing slopes. The bonds with the facetted snow are improving while the surface hoar &/or sun crust interface is weak.  Recent tests on this interface show shears trending towards Resistant Planar.  It should be noted that the interface has the full attention of professional operators in the region.Previous SW winds redistributed the new snow (dramatically in some areas) to create widespread wind slabbing on lee and open features in the alpine and exposed treeline. Where the wind has been strongest, wind slabs are much lower on slopes than normal.The midpack is well bonded and strong. The deep crust/facet combo from early November still exists and concern remains (although unlikely) for triggering this layer from a shallow spot.

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