Bollettino valanghe

South Columbia

Mar 19 – 20, 2021Avalanche Canada
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Archiviato · scaduto 6 years ago

Pericolo valanghe

Sun
Mon
Alta quota
2 · Moderato
Limite del bosco
1 · Debole
Sotto il limite
1 · Debole
Apri la mappa completa

In sintesi

Potentially touchy wind slabs may form throughout the weekend on upper elevation north, northeast & east facing slopes. These fresh slabs may rest on a thin layer of surface hoar. Convective flurries could produce locally heavy snowfall, watch for rapidly changing conditions. 

Problemi valanghivi

  • Wind Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Possible - Likely
    Dimensione
    1–2

    The best riding conditions and the highest hazard will overlap this weekend. High elevation north, northeast and east facing slopes may have a thin layer of surface hoar in place and continued southwest winds are expected to build fresh slabs above this surface hoar. Carefully assess your line for touchy wind slabs before committing. This problem is expected to increase in sensitivity over the next few days as new snow and wind continue to build the slab. Steep, convex slopes below alpine ridge tops are the most likely places to trigger these slabs. 

    If the sun pokes out it may have enough punch to initiate the recent snow as loose wet or dry avalanches from steep terrain features. 

  • Cornices

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Possible
    Dimensione
    2–3

    Periods of sunshine breaking through the clouds could pack enough punch to increase the likelihood of cornice failures. The best way to mitigate the risk is to minimize your exposure, especially when solar radiation is strong.

Confidence

Moderate - Uncertainty is due to the timing, track, & intensity of the incoming weather system.

Weather Forecast

Looks like it’s back to winter for the next few days.

FRIDAY NIGHT: Freezing level lowering to about 750 m, moderate southwest wind with potential for strong gusts, 1 to 5 cm of snow possible with convection possibly delivering as much as 10 cm to favoured locations. 

SATURDAY: Overcast, freezing level rising to about 1500 m, moderate southwest wind, 2 to 8 cm of snow expected in most locations. Convective flurries could produce 15+ cm in favoured locations.

SUNDAY: Overcast, freezing level beginning near valley bottom rising to about 1500 m, light to moderate southwest wind, 3 to 6 cm of snow possible during the day with potential for 5 to 10 cm Sunday night.

MONDAY: Broken cloud cover at dawn with skies steadily clearing throughout the day, freezing level beginning near valley bottom rising to about 1500 m, light northwest wind, 1 to 3 cm of snow possible.

Avalanche Summary

On Thursday several loose wet avalanches to size two were reported on solar alpine features. Pin wheeling was also noted on north aspects below 2000 m in the afternoon.

On Wednesday a few loose-wet avalanches were seen on steep solar aspects below treeline. 

On Tuesday, a natural 1.5 loose wet avalanche was reported from steep rocky terrain and small loose-dry sluffs were easily triggered by skier traffic on northerly aspects. 

Snowpack Summary

Isolated wind slabs may form just below ridgelines with new snow and strong wind this weekend. New snow comes to rest on a variety of old surfaces including surface hoar up to 10 mm in size that exists at treeline and above. Sunny skies and warm temperatures have formed sun crusts on solar aspects at all elevations. A crust exists up to about 2000 m on polar aspects too. Dry snow still exists on north aspects at upper elevations. Large cornices loom over alpine ridgetops.

Persistent weak layers of surface hoar, crusts, and/or facets 80-120 cm down have recently been unreactive and no recent avalanches have been reported on these layers. 

Terrain and Travel

  • Avoid freshly wind loaded features, especially near ridge crests, roll-overs and in steep terrain.
  • Look for signs of instability: whumphing, hollow sounds, shooting cracks, and recent avalanches.
  • Use caution above cliffs and terrain traps where even small avalanches may have severe consequences.
  • Cornices become weak with daytime heating or solar exposure.

Regioni coperte