Avalanche Forecast

Issued: Jan 30th, 2013 10:06AM

The alpine rating is moderate, the treeline rating is moderate, and the below treeline rating is low. Known problems include Wind Slabs.

Avalanche Canada swerner, Avalanche Canada

Summary

Confidence

Fair - Timing or intensity of solar radiation is uncertain

Weather Forecast

A ridge of high pressure looks to be dominating the pattern for the next few days. Weak systems embedded in the flow will bring light amounts of precipitation and a mix of sun and cloud on Thursday. By Friday the ridge brings sunshine and rising freezing levels.Thursday: Snow amounts 5-10 cm accompanied by moderate-strong ridgetop West winds. Alpine temperatures near -1.0 with freezing levels rising 1300 m. Friday: Mainly sunny with some upper cloud. No precipitation and ridgetop winds blowing light from the SW. Alpine temperatures rising to 2.0 degrees with freezing levels around 2100 m. Saturday: Mainly sunny possible clouds in the afternoon and no precipitation. Ridgetop winds light from the SW. Alpine temperatures near 2.0 and freezing levels rising to 2200 m.

Avalanche Summary

No new avalanche observations reported.

Snowpack Summary

Up to 30 cm of snow fell over the past few days with light to moderate NW winds. This snow is settling and gaining strength although lingering wind slabs are possible behind ridges and ribs and have proven to be touchy to rider triggers. The new snow has buried a variety of surfaces including old wind slabs, crusts and surface hoar crystals which can be found in sheltered terrain below treeline. Changing winds from the West should be strong enough to transport snow - this will create a new series of wind slabs, primarily on easterly and southerly facing slopes and in cross-loaded terrain features.The most recent buried crust/surface hoar interface is down approx. 10-30 cm, and seems to be slightly touchy in isolated sheltered areas where the surface hoar had a chance to form. Down deeper sits another surface hoar layer (40-80 cm) which seems to be gaining strength with little to no recent reactivity on it. Below this sits a generally well settled mid pack, which may be bridging a basal facet/crust layer in deeper snowpack areas. The average snowpack depth at treeline is near 170 cm.

Problems

Wind Slabs

An icon showing Wind Slabs
Recent winds have formed wind slabs in unsuspecting places (reverse loaded). Wind slabs have been touchy to rider triggers, especially in areas where a buried weakness exists. Stiff, hollow snow below your feet is a good indicator of unstable snow.
Be cautious as you transition into wind affected terrain.>Watch for whumpfing, hollow sounds, shooting cracks or recent avalanches.>Dig down to find and test weak layers before committing to a line.>

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

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1 - 4

Valid until: Jan 31st, 2013 2:00PM

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