Bollettino valanghe

Kootenay Boundary

Feb 8 – 9, 2020Avalanche Canada
Vedi sulla mappa
Archiviato · scaduto 7 years ago

Pericolo valanghe

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

In sintesi

Snowfall overnight combined with strong southwest wind will form fresh wind slabs in lee terrain features at treeline and in the alpine. Highest snowfall amounts are forecast for Kootenay Pass with 20-25 cm. Be cautious when transitioning into wind affected terrain.

Problemi valanghivi

  • Wind Slabs

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

    Moderate to strong southwest wind overnight combined with new snow will create fresh wind slabs in lee terrain features sensitive to human triggers. Highest snowfall amounts are expected at Kootenay Pass with 20-25 cm. 

    Wind has recently switched direction from southwest to northwest and back again. At treeline elevations, wind slabs may overly a crust from early February which may make for a favorable sliding surface.

Confidence

Moderate - Uncertainty is due to the speed, direction, or duration of the wind and its effect on the snowpack. Forecast snowfall amounts are uncertain.

Weather Forecast

Friday Night: Snow, accumulation 10-15 cm with Kootenay Pass receiving 20-25 cm, moderate to strong southwest wind, alpine high -4 C, freezing level 1000 m.

Saturday: Cloudy with isolated flurries, accumulation up to 5 cm, light to moderate northerly wind, alpine high -4 C, freezing level 1100 m.

Sunday: Mix of sun and cloud, moderate to strong northwest wind, alpine high -10 C, freezing level 800 m.

Monday: Mostly sunny, light to moderate northerly wind, alpine high -5 C, freezing level 900 m.

Avalanche Summary

On Thursday a few large (size 2-2.5) slab avalanches released naturally during the night. One large (size 3) slab avalanche was triggered by explosives in the west of the region. Several small (size 1-1.5) slab avalanches were triggered by skiers mainly on south and east aspects. 

On Wednesday several small (size 1) slab avalanches in the alpine were triggered by skiers. Several small (size 1) natural and skier triggered loose dry avalanches were reported in steep terrain at treeline and in the alpine. 

Snowpack Summary

Wind switching directions has redistributed recent new snow onto a variety of aspects. The snow surface varies from low density in wind sheltered areas to wind slab at all elevations. Specific terrain features at treeline and in the alpine are scoured to a crust from early February. As high as 2000 m, the upper snowpack contains a crust from recent warming and rain events. Generally the recent storm snow seems to bond well with the crust below. Several avalanches were observed to release within the recent storm snow. However, some avalanches slid on the crust below. 

Weak facet/crust layers near the base of the snowpack are particularly noteworthy in the western Boundary area.

Terrain and Travel

  • Watch for newly formed and reactive wind slabs as you transition into wind affected terrain.
  • Recent wind has varied in direction so watch for wind slabs on all aspects.
  • Be alert to conditions that change with elevation.

Regioni coperte