Bulletin d’avalanche

Lizard-Flathead

Feb 16 – 17, 2020Avalanche Canada
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Archivé · expiré 7 years ago

Danger d’avalanche

Tue
Wed
Alpin
2 · Modéré
Limite forestière
2 · Modéré
Sous la limite
2 · Modéré

Points saillants

Overnight snowfall is uncertain so be ready to dial back your terrain selection if it exceeds forecast amounts. Fresh snow will be eager to shed from steep slopes that see strong sunshine.

Problèmes avalancheux

  • Cornices

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Possible - Likely
    Taille
    1.5–2.5

    Natural cornice falls are a feature of recent reports that will likely increase with sun exposure on Sunday. Cornice falls are dangerous in their own right but they may also trigger avalanches on slopes they impact.

  • Storm Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Possible - Likely
    Taille
    1–2

    Overnight snowfall is likely to form a touchy new storm slab problem for Sunday. Depending on amounts, the problem may become widespread or instead be focused toward the wind loaded lees of exposed terrain features. Fresh accumulations are likely to shed easily from steep slopes that see sun.

Terrain and Travel

  • Seek out sheltered terrain where new snow hasn't been wind-affected.
  • Caution around slopes that are exposed to cornices overhead.
  • Be alert to conditions that change with elevation and sun exposure.

Confidence

Moderate - Forecast snowfall amounts are uncertain.

Weather Forecast

Saturday night: Cloudy with flurries bringing 5-15 cm of new snow. Moderate southwest winds.

Sunday: Diminishing cloud and easing flurries bringing up to 5 cm of new snow in the morning. Light northwest winds. Alpine high temperatures around -9.

Monday: Mainly sunny. Light west winds. Alpine high temperatures around -9.

Tuesday: Sunny. Light west winds. Alpine high temperatures around -10.

Avalanche Summary

Slightly enhanced snowfall over Thursday night brought more active avalanche conditions to the region on Friday. Reports showed several natural and explosives triggerd storm slabs reached size 2, with crown fracture depths of 20-40 cm, showing some evidence of wind loading. Northeast aspects above 1900 metres featured most prominently. Several natural cornice falls were another stand-out feature.

New avalanche observations from Tuesday were limited to a few small (size 1) wind slabs able to be skier triggered in crossloaded gully features. Observations into the alpine were limited by poor visibility. Wednesday's reports showed a transition to small dry loose releases.

Looking forward, another night of snowfall

Snowpack Summary

10-20 cm of snow from the past week has been adding to wind-affected snow and old wind slabs in exposed terrain while adding to older, settled storm snow in sheltered areas. Collectively 25-50 cm of snow now overlies a thick rain crust that exists up to roughly 2100 m. In many areas this capping crust extends to mountaintops. 

The bottom 20 cm of the snowpack consists of basal facets and decomposing crusts that have not been an active avalanche problem since December, but could reemerge as a problem after sustained warming.

Régions couvertes