Avalanche Forecast

Issued: Nov 27th, 2021 4:00PM

The alpine rating is high, the treeline rating is high, and the below treeline rating is moderate. Known problems include Storm Slabs.

Avalanche Canada JSmith, Avalanche Canada

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Large natural avalanches are expected overnight Saturday and into Sunday morning.

Travel in avalanche terrain is not recommended.

Summary

Confidence

Moderate - Forecast precipitation (either snow or rain) amounts are uncertain.

Weather Forecast

SATURDAY NIGHT: Snow/rain; 15-25 cm / Extreme, southwesterly winds / Low of -1 / Freezing level rising to 1300 m.

SUNDAY: Snow/rain; 10-15 cm / Strong, southwesterly winds / High of -1 / Freezing level lowering to 800 m

MONDAY: Mix of sun and cloud with flurries; 5-10 cm / Moderate, southwesterly winds / High of -3 / Freezing level 300 m.

TUESDAY: Snow/rain; 40-60 cm / Extreme, southwesterly winds / High of 1 / Freezing level rising to 1300 m.

Avalanche Summary

Numerous naturally triggered storm slabs up to size 3 have been reported near Shames over the last couple of days; including one large avalanche that may have failed on the early November crust near the bottom of the snowpack.

Large natural avalanches are expected at upper elevations overnight Saturday and into Sunday morning.

Snowpack Summary

Southern portion of region (around Terrace):

30-40 cm of new snow is forecast to fall overnight Saturday into Sunday morning. This will add to the 20 cm of recent snow which sits on top of a hard crust. Extreme southwesterly winds will make these fresh storm slabs most reactive on lee features at treeline and above.

A prominent crust can be found near the bottom of the snowpack.

Treeline snowpack depths are estimated to be around 200-300 cm.

Northern region (around Bear Pass):

30-40 cm of new snow is forecast to fall overnight Saturday into Sunday morning. This will add to the 60-80 cm of recent snow which was heavily wind affected. Extreme southwesterly winds will make these fresh storm slabs most reactive on lee features at treeline and above.

Below the recent snow, two weak layers of surface hoar have been reported in sheltered areas, as well as a crust near the bottom of the snowpack.

Terrain and Travel

  • Avoid exposure to overhead avalanche terrain, avalanches may run surprisingly far.
  • Avoid all avalanche terrain during periods of heavy snowfall.
  • Stick to non-avalanche terrain or small features with limited consequence.
  • Watch for signs of instability like whumpfing, hollow sounds, shooting cracks or recent avalanches.
  • Be especially cautious as you transition into wind affected terrain.

Problems

Storm Slabs

An icon showing Storm Slabs

Forecast snow and wind will form LARGE touchy storm slabs at treeline and above. These slabs will be especially reactive on leeward features.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Very Likely

Expected Size

1.5 - 2.5

Valid until: Nov 28th, 2021 4:00PM