Bollettino valanghe

South Columbia

Apr 2 – 3, 2022Avalanche Canada
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Archiviato · scaduto 4 years ago

Pericolo valanghe

Mon
Tue
Alta quota
2 · Moderato
Limite del bosco
2 · Moderato
Sotto il limite
1 · Debole

In sintesi

Westerly wind created wind slabs in lee terrain features in the alpine and treeline. These slabs are especially reactive where they overlie a crust. 

Problemi valanghivi

  • Wind Slabs

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

    Northwest winds have redistributed snow and formed wind slabs in lee terrain features in the alpine and treeline. 

    On Sunday, moderate to strong southwest wind will form fresh wind slabs in leeward (N-NE-E) terrain features in the alpine and exposed treeline. These slabs will be most reactive where they overlie a slick crust.

Confidence

High -

Weather Forecast

Saturday night: Clear with cloudy periods, trace of new snow, moderate southwest wind, alpine low -5 °C, freezing level at 600 m.

Sunday: Cloudy, up to 4 cm snow, moderate to strong southwest wind, alpine high -4 °C, freezing level at 1500 m. 

Monday: Cloudy, 20-25 cm snow, moderate to strong southwest wind, alpine high -4 °C, freezing level at 1500 m. 

Tuesday: Mainly cloudy, 5-10 cm snow, moderate westerly wind, alpine high -6 °C, freezing level at 1500 m.

Avalanche Summary

On Friday, small natural wet loose avalanches were observed. Skiers triggered small wind/storm slab and wet loose avalanches, as well as a large (size 2) wind slab avalanche. 

On Thursday, a few natural wind slabs up to size 2 were reported from the alpine on northeasterly slopes. Skier triggered dry loose and small storm slabs were easily triggered within the new storm snow up to size 1.5. 

On Wednesday, the recent storm snow was reactive to skier triggering, especially where it sat above a crust. Reports showed numerous dry loose and wind/storm slab avalanches size 1-2.

Snowpack Summary

15-35 cm of new snow overlies up to 20 cm of denser snow above 2100 m and tapers rapidly at lower elevations. 50-60 cm of snow now sits over the mid-March interface at upper elevations.

A melt-freeze crust exists on all aspects as high as 2100 m and to mountain top on solar aspects. Below the crust, the top 10-30 cm of the snowpack is moist. 

The early-December rain crust is approximately a metre off the ground. Reports have recently indicated that large slab avalanches have failed on this interface earlier this week following a rain and warming event. This layer may be dormant now due to colder weather, however, it may appear again during the next big warm-up or with increased load from wind, snow, and/or rain. 

Terrain and Travel

  • Watch for newly formed and reactive wind slabs as you transition into wind affected terrain.
  • Wind slabs may be poorly bonded to the underlying crust.
  • Pay attention to cornices and give them a wide berth when traveling on or below ridges.
  • When a thick, melt-freeze surface crust is present, avalanche activity is unlikely.

Regioni coperte