Bollettino valanghe

Northwest Inland

Jan 31 – Feb 1, 2021Avalanche Canada
Vedi sulla mappa
Archiviato · scaduto 6 years ago

Pericolo valanghe

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

In sintesi

Moderate southerly wind overnight will form fresh wind slabs in lee terrain features in the alpine and exposed treeline. Older wind slabs built by easterly and northerly outflow winds might still be reactive and harder to recognize. 

Problemi valanghivi

  • Wind Slabs

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

    Moderate southerly wind will redistribute loose snow overnight and form fresh wind slabs in lee terrain features on northerly and easterly aspects. Older wind slabs were formed on westerly aspects on previous days and may still be reactive and more tricky to recognize. Wind and soft slabs will be particularly reactive anywhere they overlie surface hoar that was reported to be widespread in many sheltered areas. 

    Loose snow avalanches (sluffs) are likely in steep and wind-protected areas and they might run longer and grow larger than expected. 

Confidence

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

Weather Forecast

SATURDAY NIGHT: Mainly cloudy, up to 5 cm new snow, moderate southerly wind, treeline temperature -11 C.

SUNDAY: Mix of sun and cloud, trace of new snow, light to moderate southerly wind, treeline temperature -9 C.

MONDAY: Mainly cloudy, trace of new snow, light southwest wind, treeline temperature -12 C.

TUESDAY: Mainly cloudy, 5 cm new snow, light westerly wind, treeline temperature -12 C.

Avalanche Summary

A large natural dry loose avalanche was reported on Thursday. Fresh small wind slabs and small dry loose avalanches (sluffs) on steep alpine slopes were reported on Tuesday. 

Isolated large avalanches failed during the storm last weekend on buried surface hoar in the southwest of the region where snowfall amounts were on the higher end (up to 15 cm). 

Sporadic deep persistent slab avalanches were reported 2-3 weeks ago (triggered with heavy loads such as explosives and cornices), but deeper weak layers appear unreactive under the current conditions.

Snowpack Summary

10-30 cm recent low density snow has buried surface hoar, which was reported as widespread below treeline and isolated at sheltered treeline and alpine locations. A buried sun crust can be found on steep solar aspects underneath the new snow. The new snow sits on widespread wind scoured surfaces, older wind slabs in alpine and exposed treeline locations and open wind affected areas below treeline. A thick crust exists near the surface below 1000 m. 

The lower snowpack has two decomposing crust layers that have been causing a deep persistent slab problem for most of the past month. The upper crust is 70-140 cm deep in the Smithers area and continues to show occasional hard sudden results in snow pits. The deeper crust at the bottom of the snowpack continues to be a problem in shallow ranges like the Babines. These layers should be unreactive under the current conditions, but shallow rocky slopes should still be carefully assessed and approached with caution. 

Terrain and Travel

  • Recent wind has varied in direction so watch for wind slabs on all aspects.
  • Watch for signs of instability like whumpfing, hollow sounds, shooting cracks or recent avalanches.
  • Watch your sluff: it may run faster and further than you expect.

Regioni coperte