Bollettino valanghe

Northwest Inland

Nov 26 – 27, 2015Avalanche Canada
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Archiviato · scaduto 11 years ago

Pericolo valanghe

Sat
Sun
Alta quota
Senza grado
Limite del bosco
Senza grado
Sotto il limite
Senza grado

In sintesi

The snowpack is extremely variable depending on aspect and elevation and does not adjust well to rapid change. Watch for rising alpine temperatures to well above zero. Check out the Mountain Information Network. Give info, get info!

Problemi valanghivi

  • Wind Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Possible - Likely
    Dimensione
    1–3
    Watch for new wind slabs on opposite slopes due to northerly winds. Destructive wind slabs from last weekends storm may still exist, watch for wide propagations, especially in the lee of ridgecrests.
  • Loose Wet

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Possible - Likely
    Dimensione
    1–3
    Increasing and strengthening warm air aloft (above 1000 m) may deteriorate snow surfaces initiating loose wet avalanches. Smaller avalanches could dig down to deeper layers, especially at higher elevations, initiating larger slab avalanches.

Weather Forecast

The above freezing layer will exist over the Northern regions through the forecast period. Temperatures could rise as high as 8 degrees above 1200 m and stay below zero with the outflow winds in the valleys. Patchy valley cloud may accompany the strengthening inversion as moisture becomes trapped. Ridgetop winds will generally be light and from the southwest.

Avalanche Summary

No new avalanches have been reported. Newly formed wind slabs may remain sensitive to human triggering and surface snow may start to deteriorate especially on solar aspects with the warming. Watch for obvious clues of instability like natural avalanches, snow balling and moist/ wet snow.

Snowpack Summary

The snowpack is extremely variable depending on aspect and elevation, with new wind slabs developing on reverse loaded southerly slopes and widespread surface crusts on all aspects at lower elevations. At upper elevations, last weekends storm likely produced stiff wind slabs on northerly aspects. The reactivity of these new wind slabs will likely change with elevation and underlying snowpack structure. The snowpack doesn't adjust well to rapid changes, so it may take several days to adjust and settle with the warm temperatures at higher elevations. Due to limited observations, I have very little confidence in what that underlying structure may be, although I suspect faceting, crusts and surface hoar may exist. How are they adjusting and reacting as shears? Are they distinct and reacting like a cash register when tested? Or are they becoming hard to find with resistant shear characteristics? If I were traveling in the mountains, I'd maintain a conservative and investigative approach and dig down to test for weak layers before committing to a slope.

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