Bollettino valanghe

Northwest Coastal

Apr 8 – 9, 2023Avalanche Canada
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Archiviato · scaduto 3 years ago

Pericolo valanghe

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

In sintesi

As storm snow continues to build, step back into conservative terrain. Reactive storm slabs are forming at all elevations.

A weak layer buried late March came alive on Friday, head to low angle terrain free from overhead hazard to minimize your exposure.

Problemi valanghivi

  • Persistent Slabs

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

    Buried layers from late March reached a tipping point and became very reactive on Friday, with impressive propagation. Of primary concern is a layer of facets and surface hoar buried 50-80 cm on shaded slopes. On other slopes, this layer is a crust with facets above. Avoid steep open slopes capable of producing large avalanches, storm snow is adding a significant load to the snowpack.

    Reactivity has been most concerning west of Stewart, however, this layer extends throughout the Northwest Coast region.

  • Storm Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Likely
    Dimensione
    1–2.5

    Fresh and reactive slabs are expected to build at all elevations as new snowfall continues to stack up. Coastal areas have seen much heavier snowfall. Expect greater reactivity and size of possible avalanches as you travel further west.

    At lower elevations precipitation may fall as rain on an already moist snowpack. Loose wet activity will become more likely as rain/wet snow continues. Avoid slopes that have moist or wet surface snow.

Confidence

Moderate

Avalanche Summary

On Friday numerous persistent slab avalanches were reported near Stewart on the March 31st buried weak layer. Natural, rider triggered and remote avalanches were triggered to size 2.5. Activity occurred on all aspects and elevations. A wind slab reported in this area on a northeast facing slope stepped down to this weak layer as well.

On Thursday operators reported loose wet activity at low elevations where temperatures remained warm. Natural and rider-triggered avalanche activity was reported within the recent storm snow, mostly to size 1, with larger results produced by explosive control methods in heavy snowfall areas.

Snowpack Summary

Recent snowfall totals may reach 50 to 80 cm in coastal areas, and taper as you move inland where about 30-50 cm of snow has fallen over the week. This continues to be redistributed by southerly winds into wind slabs on north-facing slopes. This sits over wind-affected surfaces or a crust on south-facing slopes that extends into the alpine, or weak facetted crystals.

A weak layer buried at the end of March sits 50-80 cm deep in most areas (potentially over 1m deep in immediate coastal terrain). It includes facets and surface hoar in shaded areas, and a melt-freeze crust elsewhere. This layer has shown limited reactivity within the past week.

The mid and lower snowpack are considered generally strong and well-bonded. In far northern reaches of the region, basal facets may exist which are currently considered inactive. This layer may become active with abrupt changes to the snowpack, such as rapid loading (heavy snowfall or rain) or prolonged warming.

Weather Summary

Friday Night

Mostly cloudy with 5-15 cm of snow. Moderate southerly winds. Freezing levels around 800 m.

Saturday

Cloudy with strong to extreme southerly winds. Snow intensifies with 15-40 cm possible. Higher amounts favor typical coastal terrain. Freezing levels around 1000 m.

Sunday

Cloudy with strong to extreme southerly winds. Another 15-30 cm of snow is possible. Freezing levels around 1000 m.

Monday

Cloudy, light snowfall with strong southerly winds. Freezing levels around 1000 m.

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.
  • Be carefull around freshly wind loaded features.
  • Potential for wide propagation exists, fresh slabs may rest on surface hoar, facets and/or crust.
  • Back off slopes as the surface becomes moist or wet with rising temperatures.

Regioni coperte