Bollettino valanghe

Northwest Inland

Feb 25 – 26, 2021Avalanche Canada
Vedi sulla mappa
Archiviato · scaduto 6 years ago

Pericolo valanghe

Sat
Sun
Alta quota
4 · Forte
Limite del bosco
3 · Marcato
Sotto il limite
3 · Marcato
Apri la mappa completa

In sintesi

Slabs will rapidly build with new snow and extreme wind, requiring terrain avoidance and otherwise a conservative mindset to travel safely. Treat the danger as HIGH and avoid avalanche terrain anywhere you find more than 25 cm of fresh snow.

Problemi valanghivi

  • Storm Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Likely - Very Likely
    Dimensione
    1.5–3

    15 to 35 cm of snow is expected to accumulate by Thursday afternoon, forming new storm slabs. The wind is forecast to howl from the southwest to northwest, so wind slabs will rapidly build at treeline and alpine elevations as well. Including the weekend's snow, around 40 to 80 cm of recent storm snow will have built above the surfaces formed mid-February, potentially including weak surface hoar and/or faceted grains. These slabs will remain likely for riders to trigger on Thursday. Should 25 cm or more snow accumulate, another natural avalanche cycle may occur on Thursday.

Confidence

Moderate - Uncertainty is due to the track & intensity of the incoming weather system.

Weather Forecast

WEDNESDAY NIGHT: Cloudy with afternoon snowfall, accumulation 10 to 20 cm, 60 to 80 km/h southwest wind, alpine temperature -11 C.

THURSDAY: Cloudy with snowfall, accumulation 5 to 15 cm, 40 to 60 km/h west wind, alpine temperature -9 C, freezing level 800 m.

FRIDAY: Cloudy with snowfall, accumulation 5 to 10 cm, 40 to 60 km/h west wind, alpine temperature -9 C.

SATURDAY: Cloudy with snowfall, accumulation 5 to 10 cm, 40 to 60 km/h west wind, alpine temperature -7 C.

Avalanche Summary

We are still receiving reports of widespread avalanche activity that occurred earlier this week across the region, for example as described in this MIN as well as this MIN. We also heard of a deep persistent slab releasing out of treeline terrain on a north aspect near Ningunsaw.

Looking towards Thursday, another natural avalanche cycle may occur in parts of the region as a substantial amount of new snow and extreme wind are forecast. It will be a good day to stay well away from avalanche terrain if your local riding area has more than 25 cm of fresh snow. Should you recreate in an area with less snowfall, the safe bet will be to apply a conservative mindset and avoid slopes with any negative consequence, as triggering storm and wind slabs will remain likely.

Snowpack Summary

The region may see anywhere from 15 to 35 cm by Thursday afternoon above 800 m, with associated strong to extreme southwest to northwest wind. Storm slabs are expected to build rapidly in sheltered terrain and wind slabs in exposed terrain at high elevations. Below 800 m, rain will soak a snowpack that was recently wet.

This snow will build on the 40 to 60 cm of snow that accumulated earlier this week. All of this snow overlies hard wind-affected snow in exposed terrain and weak, faceted snow or surface hoar crystals in sheltered terrain, suggesting it may take some time for the snow to bond to these surfaces.

Basal faceted snow remains part of the snowpack structure in much of the region. Once we see a substantial warm-up, we'll be thinking about the potential for the reactivation of basal layers.

Terrain and Travel

  • Travel in alpine terrain is not recommended.
  • Avoid all avalanche terrain during periods of heavy loading from new snow and wind.
  • Choose conservative terrain and watch for clues of instability.
  • Watch for signs of instability like whumpfing, hollow sounds, shooting cracks or recent avalanches.
  • Potential for wide propagation exists, fresh slabs may rest on surface hoar, facets and/or crust.

Regioni coperte