Boletín de aludes

Lizard-Flathead

Dec 12 – 13, 2021Avalanche Canada
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Archivado · caducó 5 years ago

Peligro de aludes

Tue
Wed
Alta montaña
4 · Fuerte
Límite del bosque
4 · Fuerte
Bajo el límite
3 · Notable
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Lo esencial

Avoid being in or under avalanche terrain until the new snow has time to stabilize.

Heavier snowfall amounts may be isolated to small areas. If you are riding in an area that saw less than 30 cm of snow in the last 24 hours, reduce the hazard to considerable.

Problemas de aludes

  • Storm Slabs

    • Alta montaña
    • Límite del bosque
    • Bajo el límite del bosque
    Probabilidad
    Very Likely
    Tamaño
    2–3.5

    Underneath the storm snow, there are lingering wind slabs that were bonding poorly to the icy crust below. An avalanche that starts in the storm snow has the potential to step down to these wind slabs. These wind slabs were most prominent at treeline and in the alpine on northwest through south aspects.

    If you are unsure where the old wind slabs are lurking, then assume any storm slab avalanche that starts has the potential to get bigger than expected.

    Expect storm slabs to be the deepest and most reactive in the Lizard Range. That area is expected to receive significantly more overnight snow than the rest of the region.

Terrain and Travel

  • Continue to make conservative terrain choices while the storm snow settles and stabilizes.
  • Storm slabs in motion may step down to deeper layers resulting in large avalanches.
  • Closely monitor how the new snow is bonding to the crust.

Confidence

Moderate - Uncertainty is due to the track & intensity of the incoming weather system. We are confident about the likelihood of avalanche activity, what is less certain are their possible size.

Weather Forecast

SATURDAY NIGHT: Overcast. Heavy snowfall. 15-25cm of snow expected. Strong southwest wind, up to extreme on high peaks. Freezing levels between 1000 and 1500m. 

SUNDAY: Mostly cloudy. Around 5cm of snow expected. Strong southwest wind. Freezing level around 1000m, dropping in the afternoon, back to valley bottom by midnight. 

MONDAY: Mostly cloudy with possible clear periods. 0-5cm of snow expected, another 10 cm overnight. Moderate to strong south to southwest wind. Freezing level at valley bottom in the morning, rising to 1000m through the day. Alpine high around -3 C.

TUESDAY: Mostly cloudy. 5cm of snow expected. Light to moderate southwest wind. Alpine low around -8 C.

Avalanche Summary

Expect natural and skier triggered avalanches to remain likely as the snow and wind continue.

Yesterday, avalanche control produced numerous size 1-1.5 avalanches in the storm snow.

On Friday, avalanche control work continued to trigger wind slabs up to size 2.5.

On Thursday, natural trigged storm slab avalanches were observed to size 2 near Fernie. Explosives and skiers in the same area also triggered storm slabs to size 2, all failing on the melt freeze crust. 

Snowpack Summary

A reactive, upside-down snowpack may remain until the temperature cools and the storm snow settles. 

Below 2400m, expect to find a thick and supportive melt freeze crust on all aspects down 40-80 cm. 

The snowpack holds several early season crusts about 20-30cm above the ground. Last week's heavy rain saturated the snowpack and has begun to break down this crust at treeline and below, creating a cohesive lower snowpack.

Snowpack depths range from 40-130 cm at treeline elevations. The snowpack tapers quickly below 1800m.

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