Bollettino valanghe

Purcells

Mar 16 – 17, 2016Avalanche Canada
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Archiviato · scaduto 11 years ago

Pericolo valanghe

Fri
Sat
Alta quota
3 · Marcato
Limite del bosco
3 · Marcato
Sotto il limite
2 · Moderato
Apri la mappa completa

In sintesi

As stormy weather tapers-off and a dry ridge  builds over the province, solar radiation will become the driver for natural avalanche activity. Watch your overhead hazard as avalanches could travel farther than anticipated.

Problemi valanghivi

  • Cornices

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Possible - Likely
    Dimensione
    2–5
    Daytime warming and solar radiation will promote large cornice failures which could, in turn, trigger a large avalanche on the slope below.

  • Persistent Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Possible - Likely
    Dimensione
    3–5
    The late February layer is becoming less likely to trigger, but it continues to surprise riders with large avalanches. I'd aim for well-supported slopes without convexities, and I'd be increasingly cautious as solar radiation comes into play.

  • Loose Wet

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Likely
    Dimensione
    1–4
    As the sun comes out, surface avalanche conditions will include a mix of wind slabs in high elevation lee terrain, and pushy loose wet activity on steep, sun-exposed slopes. Loose wet avalanches may also trigger deep and destructive slab avalanches.

Confidence

High

Weather Forecast

A dry ridge of high pressure will develop over the region bringing clear skies for Thursday and Friday. Increased cloud is forecast for Saturday. Ridgetop winds will be light to moderate from the northwest on Thursday morning, and then become light for the rest of the forecast period. Freezing levels will hover around 1200m on Thursday, 1500m on Friday and 2100m on Saturday.

Avalanche Summary

Explosives control on the west/central part of the region produced slab avalanches to size 3 on Tuesday. In many cases, avalanches failed within the recent storm snow; however, a few of the bigger avalanches stepped down to the late February weak layer. A size 2 persistent slab avalanche was also noted on Sunday in the Dogtooth Range. The avalanche, which failed on a northeast aspect at 2200m, started as a smaller wind slab and stepped-down to the late February layer. This illustrates the touchy conditions in some areas. As stormy weather tapers-off and a dry ridge builds over the province, solar radiation will become the driver for natural avalanche activity.

Snowpack Summary

On lee features at treeline and in the alpine light amounts of new snow overlie older wind slabs while intermittent sunny skies have likely promoted a melt-freeze cycle on some sun-exposed slopes. 35-80 cm below the surface you'll find a persistent weak layer comprised of surface hoar, facets and/or a thick crust. This layer, which was buried on February 27th, seems variably reactive. In other words, it's still really touchy in some places while in other places it's really tough to trigger, and there's not much of a reliable pattern telling us what exact aspects are most suspect. I'd continue to be suspicious of steep, unsupported features at treeline and in the alpine as this layer has the potential for large avalanches. 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 either still has the isolated potential to produce very large avalanches with a heavy trigger or significant warming. At ridgetop, cornices are huge and could be become increasingly touchy with forecast solar radiation.

Regioni coperte