Avalanche Forecast

Issued: Feb 4th, 2013 9:03AM

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

Avalanche Canada swerner, Avalanche Canada

If your receive less then 20 cm of new snow in your local riding area, consider the danger ratings to be one step to high on Tuesday.

Summary

Confidence

Fair - Forecast snowfall amounts are uncertain

Weather Forecast

Tuesday: The trailing cold front has brought temperatures back down to seasonal norms. The next well developed system brings light-moderate (10-20 cm) snow amounts. Ridgetop winds will blow strong from the SW and alpine temperatures will be near -6. Freezing levels will hover around 1300 m. Wednesday: Upper disturbances embedded in the SW flow will bring continued stormy conditions. Snow amounts 10-15 cm throughout the day, tapering off overnight. Ridgetop winds will continue to be moderate-strong from the SW. Alpine temperatures near -7 and freezing levels around 1100 m. Thursday: Week unsettled conditions will prevail with no significant precipitation. Ridgetop winds will blow light from the South. Alpine temperatures near -8 and freezing levels will stay near 900 m in the afternoon then falling overnight.

Avalanche Summary

No new avalanches reported. Aggressive slope testing in the Allen Creek area produced no results on steep wind loaded slopes.

Snowpack Summary

The old storm snow has settled into a dense slab that can be triggered by skiers or sledders and produce avalanches up to size 2.0. There has been a lot of wind transport and wind slab formation in the alpine. Forecast new snow and strong SW winds will build fresh wind slabs and add to the recent storm slab which sits on a spotty and variable weak interface buried  40-80 cm down (in isolated locations). Professionals are finding the early January surface hoar layer to be well preserved in more locations below 2000 metres than had been suspected. Use extra caution on open slopes, cutblocks and convex rolls at and below treeline where buried surface hoar may be preserved.

Problems

Wind Slabs

An icon showing Wind Slabs
Old wind slabs continue to be a concern, and new wind slabs are will build with the next pulse of moisture. Concerning areas are on lee slopes and behind terrain features like ridges and ribs, especially in areas that host a buried weak layer below.
Avoid freshly wind loaded features.>Whumpfing, shooting cracks and recent avalanches are all strong indicators of an unstable snowpack.>Use ridges or ribs to avoid pockets of wind loaded snow.>

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

Elevations: Alpine, Treeline.

Likelihood

Likely

Expected Size

1 - 5

Valid until: Feb 5th, 2013 2:00PM

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