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Archived

Avalanche Forecast

Dec 10th, 2013–Dec 11th, 2013
Alpine
2: Moderate
The avalanche danger rating in the alpine will be moderate
Treeline
2: Moderate
The avalanche danger rating at treeline will be moderate
Below Treeline
1: Low
The avalanche danger rating below treeline will be low
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
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.

Confidence

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

Weather Forecast

Interior regions will start to see moderate amounts of snow, gradual warming and strong ridgetop winds as the warm front of the Pacific Frontal systems arrives on Wednesday.Wednesday: Cloudy. Snow amounts 5-10 cm. Alpine temperatures near -9. Ridgetop winds moderate from the West. Thursday: Cloudy with flurries near 4 cm. Alpine temperatures near -10. Ridgetop winds moderate, gusting strong from the West.Friday: Cloudy with snow mounts near 5 cm. Alpine temperatures -8. Ridgetop winds light from the SW. On Friday a weak ridge may stall precipitation later in the day, and bring some sunny breaks.

Avalanche Summary

No recent avalanche observations have been reported.

Snowpack Summary

Strong NE winds have reverse loaded and formed isolated wind slabs in the leeward side of SE through West aspects. Loose dry surface sluffing from steeper terrain may occur, so use caution near terrain traps like cliffs, and depressions.Widespread surface hoar development and surface faceting exists from the previous cold temperatures and is now getting buried by incremental snowfall amounts. Snowpack depths at treeline vary across the region, averaging 70-110 cm. In the Southern part of the region there is 40-70cm of new snow over the late-November surface hoar/ crust/ facet interface that may be reactive, especially in sheltered northerly aspects where the surface hoar was better preserved.In the Northern part of the region the lower/mid snowpack is fundamentally weak, composed of an early season crust (more prevalent on north aspects) and weak faceted crystals and depth hoar above and below the crust. This persistent slab may be stubborn to trigger, but if triggered have high consequences.

Avalanche Problems

Wind Slabs

Winds from the North have redistributed snow forming wind slabs in lee terrain. Wind slabs found on these aspects are not typical, and they may surprise you.
Avoid freshly wind loaded features.>Avoid traveling in areas that have been reverse or cross-loaded by winds.>

Aspects: North, North East, East, South East.

Elevations: Alpine, Treeline.

Likelihood: Possible

Expected Size: 1 - 3

Persistent Slabs

In deeper snow areas, it may be possible to trigger an avalanche on a layer of buried surface hoar. In shallower ones, watch for a weak sugary facet layer near the base of the snowpack.
Dig down to find and test weak layers before committing to a line.>Whumpfing, shooting cracks and recent avalanches are all strong indicators of unstable snowpack.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood: Unlikely - Possible

Expected Size: 2 - 5