Bollettino valanghe

Lizard-Flathead

Dec 25 – 26, 2022Avalanche Canada
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Archiviato · scaduto 4 years ago

Pericolo valanghe

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

In sintesi

Recent snow and strong winds have built wind slabs at all elevations.

A buried surface hoar layer may increase reactivity, and small avalanches may step down to deeper weak layers.

Problemi valanghivi

  • Wind Slabs

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

    Fresh snow and strong winds has built new and reactive slabs. Expect winds to redistribute snow at treeline and alpine elevations into deeper and more reactive slabs in wind loaded features. Where strong winds are observed slabs could be found further down slope than expected.

    Expect slabs to be reactive as they sit over a variety of weak surfaces - facets, a crust and/or surface hoar.

  • Persistent Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Possible
    Dimensione
    1.5–3

    Two concerning persistent weak layers can be found in the snowpack. The first is a surface hoar/crust layer from early December and the second is a surface hoar, facet or crust layer from mid November. These layers are most concerning on sheltered treeline features where surface hoar is most likely to be preserved.

Confidence

Moderate

Avalanche Summary

On Thursday loose dry avalanches to size 2 were reported in steep terrain features.

On Tuesday explosive control produced a few small avalanches, up to size one.

A natural size 2.5 persistent slab avalanche was reported, thought to have occurred on Tuesday. This avalanche occurred on a northeast aspect, 2000 m on a reloaded bed surface.

Snowpack Summary

New snow accumulates over the day, redistributed into larger deposits in east and north facing terrain. Slabs form over facets, surface hoar or a crust and may not bond well.

Around 50cm deep a layer of surface hoar at treeline and a thin crust on steep south facing slopes exists buried in early December.

The primary concern in the snowpack is the mid-November layer consisting of facets and surface hoar, buried around 80 cm deep. This layer could become more reactive as temperatures increase on Monday and Tuesday.

The snowpack in the forecast region is quite variable with snowpack depths at treeline varying from 100cm to 200cm.

Weather Summary

Saturday Night

Mostly cloudy with 10-15 cm of snow. Strong westerly winds ease back to moderate. Freezing level below 500 m.

Sunday

Mostly cloudy with light flurries bringing trace amounts of new snow. Moderate westerly winds. Freezing levels around 500 m, high temperatures of -7°C.

Monday

Cloudy with 10-15 cm of mixed precipitation expected. Strong southwest winds return. Freezing levels rise, to around 1000 m with an above freezing layer likely from 1300 to nearly 2500 m in the south. High temperatures of +2°C.

Tuesday

Wet snow and rain continues overnight with another 15 mm forecast, while freezing levels rise to around 1800 m over the day.

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

  • Storm slab size and sensitivity to triggering will likely increase through the day.
  • Watch for fresh storm slabs building throughout the day.
  • Storm slabs in motion may step down to deeper layers resulting in large avalanches.

Regioni coperte