Boletín de aludes

Lizard-Flathead

Mar 2 – 3, 2022Avalanche Canada
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Archivado · caducó 5 years ago

Peligro de aludes

Fri
Sat
Alta montaña
4 · Fuerte
Límite del bosque
3 · Notable
Bajo el límite
3 · Notable
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Lo esencial

Though natural avalanche activity will taper off, conservative decision making is essential to let the snowpack adjust to the recent 90+ mm of load that the Lizard Range has received. 

Seek out low angle, well supported terrain away from overhead hazard.

Problemas de aludes

  • Persistent Slabs

    • Alta montaña
    • Límite del bosque
    • Bajo el límite del bosque
    Probabilidad
    Possible
    Tamaño
    2–3

    Storm avalanches have the potential to step down to this deeper persistent layer in sheltered north-facing treed terrain.

    Persistent slab avalanches are still possible due to a layer of buried surface hoar that is likely down around 50-100 cm. This problem is tricky to pin down because of its spotty distribution (it isn't a problem everywhere). It has been most reactive recently in the Flathead with reports of rider triggering, whumpfing and cracking a week ago.

  • Storm Slabs

    • Alta montaña
    • Límite del bosque
    • Bajo el límite del bosque
    Probabilidad
    Likely
    Tamaño
    1–3

    Human triggered avalanches will continue to be likely so make conservative terrain choices and give the recent storm snow time to settle and stabilize.

    With no overnight refreeze, elevated freezing levels, and rain-soaked snow at lower elevations, storm slabs may entrain wet loose snow and run further than expected. 

  • Loose Wet

    • Alta montaña
    • Límite del bosque
    • Bajo el límite del bosque
    Probabilidad
    Possible
    Tamaño
    1–2

    Depending on if we get an overnight refreeze, loose wet avalanches may be a concern at lower elevations where rain has destabilized the snowpack causing it to lose cohesion. These avalanches can start from a point and pick up a surprising amount of mass, especially in steep terrain and gully-type features. Storm slabs may entrain wet loose snow at lower elevations and run further than expected. 

Terrain and Travel

  • Continue to make conservative terrain choices while the storm snow settles and stabilizes.
  • Use small low consequence slopes to test the bond of the new snow.
  • Shooting cracks, whumphs and recent avalanches are strong indicators of an unstable snowpack.
  • Storm slabs in motion may step down to deeper layers resulting in large avalanches.

Confidence

Moderate - Uncertainty is due to how the snowpack will react to the forecast weather.

Weather Forecast

Convective pulses and freezing levels are hard to pin down. There is also a system just south of the border that could clip our region for greater than forecast precipitation amounts over the next couple of days.

Tuesday Night: Precipitation continues with 5-10 mm, moderate southwest wind, uncertainty around overnight recovery, treeline temperatures around zero.

Wednesday: Flurries possible 5-10 cm, light to moderate southwest wind, but freezing could still rise to about 1700 m during the day.

Wednesday Night: Light flurries 0-5 cm, light variable winds, freezing levels should drop back to valley bottom.

Thursday: Overcast with flurries 5-10 cm, light variable wind, freezing levels 1300-1500 m, treeline highs around zero.

Friday: Light flurries ease overnight, some clearing during the day, freezing levels drop substantially, treeline highs of -3.

Avalanche Summary

A widespread storm slab avalanche cycle with size 1-3 avalanches on a variety of aspects and elevations was reported from the Lizard Range on Tuesday. Check out this recent MIN report taken from within the ski area boundary looking out of bounds towards the Mammoth Droppings.

Snowpack Summary

The storm started cool and ended warm. The Lizard Range has received over 90 mm of water from this system which has translated to about 40-50 cm of heavy, upside down type snow. Rain runnels have been reported up to 1700 m. All of this new load sits on a variety of old surfaces like sun crusts on south-facing terrain, freezing rain crusts, old wind-pressed snow or cold, weak snow crystals on shaded aspects. Moderate to strong southwest winds have likely contributed to cornice growth as well.

Storm slabs or loose wet avalanches may step down to old persistent layers such as the surface hoar layer buried at the end of January. The distribution of this layer is spotty in nature but has produced avalanches and snowpack test results in the past week, mostly in the Flathead. While it does not appear to be as widespread or reactive in the Lizard Range, it has been found in some locations. 

The lower snowpack is well consolidated, with a crust/facet layer from early-December found near the bottom of the snowpack. It is currently considered dormant but with big rain on snow events, operators will be on guard. Check out the forecaster blog for more information. 

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