Archived

Avalanche Forecast

Nov 30th, 2013–Dec 1st, 2013

Alpine

3: Considerable

The avalanche danger rating in the alpine will be considerable

Treeline

3: Considerable

The avalanche danger rating at treeline will be considerable

Below Treeline

2: Moderate

The avalanche danger rating below treeline will be moderate

Alpine

3: Considerable

The avalanche danger rating in the alpine will be considerable

Treeline

3: Considerable

The avalanche danger rating at treeline will be considerable

Below Treeline

2: Moderate

The avalanche danger rating below treeline will be moderate

Alpine

3: Considerable

The avalanche danger rating in the alpine will be considerable

Treeline

2: Moderate

The avalanche danger rating at treeline will be moderate

Below Treeline

2: Moderate

The avalanche danger rating below treeline will be moderate

Regions: Purcells.

Avalanche danger is increasing as the storm moves into the region. The new storm snow may not bond to the recent buried weak layers.

Confidence

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

Weather Forecast

Overnight and Sunday: Moderate to locally heavy precipitation overnight as the arctic front collides with Pacific moisture. Expect strong westerly winds ahead of the arctic air, and moderate northerly winds after the passage of the cold front.Monday: Precipitation should end during the day. Expect clearing skies and cold valley temperatures.Tuesday: Clear and cold with moderate Northeast winds.

Avalanche Summary

No recent avalanche activity has been reported. New storm slabs are expected to develop overnight. Storm slab avalanches may be easily triggered where recently buried weak layers exist. The new load of storm snow, or storm slabs in motion may cause avalanches to release on this crust layer. The most likely place you would trigger this layer is on smooth, planar, north facing slopes.

Snowpack Summary

New storm slabs are developing above weak surface layers of facetted crystals and melt/freeze crusts. These recently buried weak layers may not support the new load of storm snow that is forecast. The deeply buried early season crust continues to be a concern. There have been reports of weak sugary crystals at the crust interface that may create an easy sliding surface and allow for wide propagations.

Avalanche Problems

Storm Slabs

New storm slabs are developing above recently buried weak layers. Strong winds and forecast heavy snow falls may result in easy triggering from adjacent terrain features.

The new snow may require several days to settle and stabilize due to the presence of newly buried weak layers.>Minimize exposure during periods of heavy loading from new snow, wind.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood: Likely

Expected Size: 1 - 4

Persistent Slabs

The new load of storm snow may overload the deeply buried weak layer. Storms slabs that are in motion may trigger the deeply buried weak layer resulting in wide propagations and very large avalanches.

Be aware of the potential for large, deep avalanches due to the presence of a buried crust/ facet combo.>Storm slabs in motion may trigger deeper instabilities.>

Aspects: North, North East, East.

Elevations: Alpine, Treeline.

Likelihood: Possible

Expected Size: 3 - 6