Lawinenlagebericht

Purcells

Mar 23 – 24, 2016Avalanche Canada
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Archiviert · abgelaufen 11 years ago

Lawinengefahr

Fri
Sat
Hochgebirge
3 · Erheblich
Waldgrenze
2 · Mässig
Unterhalb
2 · Mässig

Kernpunkte

New snow and strong winds overnight will increase the avalanche danger. New snow may release as loose wet avalanches when temperatures rise during the day.

Lawinenprobleme

  • Cornices

    • Hochgebirge
    • Waldgrenze
    • Unterhalb der Waldgrenze
    Wahrscheinlichkeit
    Possible - Likely
    Größe
    3–5
    Cloud cover and reduced solar may reduce likelihood, but forecast new snow and wind may increase the load on fragile cornice structures. Avoid slopes below cornices and chutes with corniced entrances.
  • Persistent Slabs

    • Hochgebirge
    • Waldgrenze
    • Unterhalb der Waldgrenze
    Wahrscheinlichkeit
    Possible
    Größe
    3–6
    The late February persistent weak layer has been remotely triggered as recently as Monday March 21st on a southeast aspect in the alpine. This problem may be more likely in the north of the region.
  • Storm Slabs

    • Hochgebirge
    • Waldgrenze
    • Unterhalb der Waldgrenze
    Wahrscheinlichkeit
    Possible - Likely
    Größe
    1–3
    Forecast new snow and wind are expected to develop new storm slabs at all elevations. Moist snow below treeline may release as loose wet avalanches during daytime heating.

Confidence

Moderate - Timing, track, or intensity of incoming weather system is uncertain

Weather Forecast

Moderate snowfall (5-10 cm) overnight with moderate southwest winds and freezing level staying above 1300 metres. Continued light snow on Thursday with moderate to strong westerly winds, freezing levels rising to 1500 metres, and a chance of sunny breaks in the afternoon. Freezing down to valley bottoms on Friday morning with lingering flurries early in the day, becoming mostly sunny with light northwest winds. A mix of sun and cloud on Saturday with westerly winds, there is some uncertainty on the amount of sun at this time.

Avalanche Summary

Some explosives control on cornice on Tuesday resulted in releases up to size 2.5 on northerly aspects. We had a report on Monday of another skier remote triggered avalanche size 2.5 from 200 metres away on a southeast aspect at 2320 metres, believed to have released on the February 27th weak layer. A MIN report from Monday at Gorman lake in the Dogtooth range describes "a lot of cornice failures", as well as "many slides running full path." On Sunday, large cornice releases triggered persistent slabs on slopes below up to size 3.0 in the central part of the region, and a group of skiers remotely triggered a size 2.5 from 6 metres away on a southeast aspect at 2400 metres in the north of the region.

Snowpack Summary

Forecast new snow and wind are expected to develop a new storm slab above a mix of crusts on solar aspects, moist snow up to about 1800 metres, and dry snow or recent wind slabs on shaded high alpine aspects. Cornices continue to be described as large and fragile, and may fail with additional loading from forecast snow, or from high daytime temperatures. Buried persistent weak layers continue to be a concern for remote triggering in isolated areas where crusts are not strong enough to "bridge" the weakness. The late February surface hoar/crust weak layer is down 40-90 cm. This layer is still reactive to human triggers in some places while in other spots it's really tough to trigger, and there's not much of a reliable pattern telling us what exact aspects are most suspect. Deeper weak layers from mid-February and early January are now down 50-90cm and 70-120cm respectively. Triggering an avalanche on either of these layers has become unlikely but still has the potential to produce very large avalanches in isolated locations.

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