Avalanche Forecast

Issued: Jan 16th, 2017 3:49PM

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

Avalanche Canada mgrist, Avalanche Canada

Conservative terrain use is essential. Rein in your exposure and avoid slopes that have consequences if they were to slide.

Summary

Confidence

Moderate - Timing, track, or intensity of incoming weather system is uncertain

Weather Forecast

We're expecting moderate snowfall in the forecast period but amounts are tapering off towards Thursday. TUESDAY: An additional 15-20 cm in the south and 5 cm in the north. Winds moderate (20 - 40 Km/hr) from the south. Freezing level 1100m in the south and 900m in the north. Alpine temperatures near +1 in the south and -2 in the north. WEDNESDAY: 5-15 cm snow in the south and 10cm in the north. Freezing levels around 1100m. Winds moderate gusting strong (40-80 Km/hr) southwesterly. Alpine temperatures +1 in the south to -3 in the north. THURSDAY: Scattered flurries with up to 5cm snow. Winds moderate (25-40 Km/hr) from the southwest. Freezing level 800m.  Alpine high temperatures -1 in the south and -5 in the north.

Avalanche Summary

A widespread natural avalanche cycle with storm slabs and loose dry avalanches occurred on all elevations with steep aspects throughout the weekend.

Snowpack Summary

We've had a significant warming trend since the arctic outbreak, and a large storm snowfall gradient (25-35cm in the south ; 60-80cm near Stewart). The new snow fell with moderate to strong SW winds, and formed touchy soft slabs and wind slabs. Expect this new snow to bond poorly to all the windslabs (and a spotty layer of surface hoar and facets buried Jan 12th) that formed during last week's arctic outbreak conditions. The older wind slabs sit on a variable interface composed of hard wind slabs, weak surface hoar (Jan 5/6 layer) and faceted snow. If you're starting to think it's a dog's breakfast, you're right! With the recent new snow loading, the deeper slabs have remained reactive, especially on southwest facing features near ridge crests. Deeper in the snowpack, the Christmas surface hoar layer (buried 70-120 cm) is still preserved in some southern areas and has been reactive in sheltered areas and steep open features at treeline and below treeline. Lower elevations (below treeline) have moist snow below 1000m elevation, making for heavy and difficult riding.

Problems

Storm Slabs

An icon showing Storm Slabs
Lots of storm snow sits on a complex mix of wind slabs, surface hoar and facets. Conservative terrain use is essential!
Minimize exposure during periods of heavy loading from new snow and wind.If triggered the storm/wind slabs may step down to deeper layers resulting in large avalanches.Use conservative route selection, choose moderate angled and supported terrain with low consequence.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Likely

Expected Size

1 - 4

Persistent Slabs

An icon showing Persistent Slabs
It is still possible to trigger avalanches on buried weak layers (Dec 25, Dec 30, Jan 5th, Jan 12th surface hoar) ... or have a smaller avalanche 'step down' and trigger deeper instabilities.
Be aware of the potential for wide propagations.Use conservative route selection, choose moderate angled and supported terrain with low consequence.Be aware of thin areas that may propogate to deeper instabilites.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Unlikely - Possible

Expected Size

1 - 3

Valid until: Jan 17th, 2017 2:00PM