Avalanche Forecast

Issued: Dec 16th, 2013 8:24AM

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

rbuhler, Avalanche Canada

South Rockies.

Summary

Confidence

Fair - Due to the number of field observations

Weather Forecast

On Tuesday, a low pressure system will move across central BC. While the system is expected to miss the South Rockies, the associated warm front will cause freezing levels to rise even higher, up to around 2300m. A weak ridge of high pressure will build after the low passes. The associated cold front on Wednesday will bring light snowfall to the region. Another low pressure system is expected to hit the coast on Thursday.Tuesday: A mix of sun and cloud, freezing levels as high as 2300m, moderate westerly alpine windsWednesday: Light snowfall, freezing levels dropping to valley bottom, light SW winds switching to NE during the dayThursday: A mix of sun and cloud, light NE winds switching to SW during the day

Avalanche Summary

No new avalanches reported.

Snowpack Summary

Recent incremental snowfall has started to bury the mid-Dec surface hoar and the previously faceted upper snowpack. Snowpack depths at treeline seem to vary from 50 - 110 cm with high variability in wind-exposed areas. Buried surface hoar/facets/crust (late-Nov interface) are down approximately 30-40cm. The base of the snowpack is made up of weak facets and depth hoar. This deep persistent weakness may be stubborn to trigger, especially in deeper snowpack areas, but the sensitivity to triggers likely increases in shallower locations, especially on a steep, convex slopes. In some below treeline areas the snowpack is below threshold and early season hazards like open creeks and stumps remain a concern.

Problems

Wind Slabs

Wind slabs have developed recently on a variety of aspects due to shifting winds. Expect to encounter these deep deposits of wind-transported snow below ridge crests and behind terrain features.

Be cautious as you transition into wind affected terrain.>Be careful with wind loaded pockets. Be aware of wide variation in snowpack depth>

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

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 3

Persistent Slabs

Sugary facets at or near the base of the snowpack are most likely triggered on steep, convex slopes with a thin snowpack. In deeper snowpack areas you may find a stubborn buried surface hoar layer.

Whumpfing, shooting cracks and recent avalanches are all strong inicators of unstable snowpack.>Dig down to find and test weak layers before committing to a line.>Avoid shallow snowpack areas on steep, convex terrain where triggering is more likely.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Unlikely - Possible

Expected Size

1 - 4

Valid until: Dec 17th, 2013 2:00PM