Bollettino valanghe

Northwest Inland

Mar 22 – 23, 2022Avalanche Canada
Vedi sulla mappa
Archiviato · scaduto 5 years ago

Pericolo valanghe

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

In sintesi

A crust on the surface will make triggering an avalanche less likely but we still have uncertainty about a buried weak layer. Wind slabs likely remain triggerable at elevations where snow has remained dry.

Problemi valanghivi

  • Wind Slabs

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

    Wind slabs likely remain triggerable at elevations where the snow has remained dry. 

  • Persistent Slabs

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

    A couple of layers of weak crystals in the top 50 cm of the snowpack. are reportedly breaking down. This problem has likely become more difficult to trigger as a bridging crust forms over wet surface snow, but we don't have enough evidence to rule it out yet.

Confidence

Moderate - Uncertainty is due to extremely variable snowpack conditions reported through the region.

Weather Forecast

Tuesday night: Flurries around 5 cm. Strong southwest wind. Alpine high around -8 °C. Freezing level dropping to valley bottom.

Wednesday: A mix of sun and cloud. Moderate southwest wind. Alpine high around -6 °C. Freezing level 1000 m. 

Thursday: A mix of sun and cloud. Light southeast wind. Alpine high around -5 °C. Freezing level 1000 m.

Friday: A mix of sun and cloud. Light south wind. Alpine high around -4 °C. Freezing level 1200 m.

Avalanche Summary

On Monday, natural and skier controlled wind slabs size 1.5 were reported. Over the last two days large, (size 2-3) avalanches have resulted from natural cornice failures triggering wind slabs on slopes below.

Persistent slab avalanches on a weak layer of surface hoar crystals buried in late February surprised a few people last week with accidental and remote triggers. The layer was most active on north-northeast aspects between 1200 and 1600 m in areas north of Hazelton.

Snowpack Summary

Wet surfaces up to 1700 m have likely refrozen into a crust. Wind slabs may be found at high elevations that remained dry.

A couple of layers of weak crystals exist in the upper snowpack, most often found on north to east aspects around treeline. We suspect that the surface crust will help bridge these layers, decreasing their likelihood of triggering.

A thick crust formed in mid-February is now buried 50-80 cm deep. It is unlikely to present an avalanche problem under the current conditions and in fact bridges any underlying instabilities in the lower snowpack.

Terrain and Travel

  • A crust on the surface will help bind the snow together, but may make for tough travel conditions.
  • Watch for areas of hard wind slab on alpine features.
  • Surface hoar distribution is highly variable. Avoid generalizing your observations.
  • Carefully evaluate bigger terrain features on an individual basis before committing to them.
  • Use extra caution around cornices: they are large, fragile, and can trigger slabs on slopes below.

Regioni coperte