Bollettino valanghe

Sea To Sky

Feb 14 – 15, 2023Avalanche Canada
Vedi sulla mappa
Archiviato · scaduto 4 years ago

Pericolo valanghe

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

In sintesi

Dangerous avalanche conditions exist in the alpine where storm snow and strong winds have built fresh wind slabs.

Be alert to conditions that change with aspect and elevation, especially on slopes being impacted by direct sun. Periods of intense solar radiation could quickly initiate a natural avalanche cycle.

Problemi valanghivi

  • Wind Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Possible
    Dimensione
    1–2.5

    Strong southwest winds have transported available snow and built fresh wind slabs in treeline and alpine lees. Wind slabs may be sitting on a crust making them especially reactive to ridder triggering.

    On Tuesday winds switch to light from the north so watch for winds reverse-loading exposed features at higher elevations.

    During periods of direct sun watch for slab properties increasing in surface snow. Minimize exposure to steep sun-exposed slopes, especially when solar radiation is strong.

  • Persistent Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Unlikely - Possible
    Dimensione
    1.5–3

    Two weak layers consisting of a crust with small facets found above them have been reactive to rider traffic in the last week. The first, down 40-100 cm has been reactive at treeline in the Rhododendron and Pemberton Icefields area. The second is found down 60-150 cm and up to 1900 m. Both of these layers seem like isolated problems at the moment but if triggered they will result in large consequential avalanches.

Confidence

Moderate

Avalanche Summary

On Monday afternoon, search and rescue technicians responded to a fatal avalanche incident north of the Sea to Sky region. The avalanche is believed to have occurred on Saturday and was initiated in a shallow rocky area. See the MIN for more details.

On Saturday, wind-affected snow was reported to be reactive to skier traffic. A size 2 wind slab avalanche was skier triggered on a west aspect at 1700 m as the skier passed over a convex roll. See MIN for photos of the slide. A skier accidental size 1.5 storm slab avalanche was reported on a steep, northeast, treeline feature.

Evidence of several size 3 natural slab avalanches was observed. It is believed these avalanches ran within the storm on the late January persistent weak layer.

On Wednesday, a rider triggered a size 2.5 persistent slab avalanche on a weak layer from mid-January. See MIN for photos and details.

Snowpack Summary

5-10 cm of recent storm snow overlies 40-70 cm of wind-affected snow. As you descend in elevation wind effect decreases and the temperature effect increases and the new snow may overlie a crust.

A series of crusts are found in the mid-pack at varying depths throughout the region. A crust from late January is found at all elevations down 40-100 cm with small facets above it. In the Rhododendron and Pemberton Icefield area, this crust has been reactive to skier traffic and in test pits at treeline. In the Brandywine area, a crust found 60-150 cm deep resulted in a few surprisingly large rider-triggered avalanches in the past few days. This layer exists to 1900 m.

Total snowpack depths are reaching 300 cm in some areas.

Weather Summary

Monday Night

Partly cloudy with isolated flurries, 2-3 cm accumulation. West winds switch to the north 20 km/h. Treeline temperature -8 °C. Freezing levels drop from 1000 m to valley bottom.

Tuesday

Sunny. Light variable winds. Treeline temperature -10 °C. Freezing level 800 m.

Wednesday

Mainly sunny with clouds increasing in the afternoon. Winds west 10 to 25 km/h. Treeline temperature -7 °C. Freezing level 600 m.

Thursday

Mix of sun and cloud with isolated flurries, trace accumulation. Winds southwest 20 km/h gusting to 40 km/h. Treeline temperature -8 °C. Freezing level 800 m.

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

  • Be carefull around freshly wind loaded features.
  • Avoid steep, rocky, and wind effected areas where triggering slabs is more likely.
  • Potential for wide propagation exists, fresh slabs may rest on surface hoar, facets and/or crust.
  • Avoid exposure to overhead hazards when solar radiation is strong.

Regioni coperte