Avalanche Forecast

Issued: Mar 18th, 2012 4:00PM

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

triley, Avalanche Canada

Cariboos.

Summary

Confidence

Fair - Timing or intensity of solar radiation is uncertain on Monday

Weather Forecast

A ridge of high pressure with light winds and many sunny periods are expected on Monday over all of the interior regions. The airmass is still unsettled, and some areas may develop periods of convective flurries. A Pacific frontal system is forecast to move onto the coast during Monday evening, and should develop cloud and precipitation in the Interior around midnight. Expect winds to increase to moderate from the southwest and precipitation to be moderate to heavy by Tuesday morning. This system is expected to continue during the day and into Wednesday morning.

Avalanche Summary

No new avalanche activity has been reported. Forecast sunshine on Monday may cause another natural avalanche cycle.

Snowpack Summary

Periods of sunshine have caused moist snow on solar aspects up to about 1500 metres. Recent cornice growth has made cornices unstable. The new snow has added to the well consolidated storm slab that overlies weak surfaces that formed early February. This interface, which lies between 1 and 2 metres below the surface, includes a widespread surface hoar instability that, depending on aspect and elevation, may exist in combination with facets or crusts. These persistent weak layers have been reactive all week and remain a concern at all elevations. The weight of new snow, near-surface avalanches, sleds, and skiers may easily trigger these deeper weaknesses creating unexpectedly large and destructive avalanches.

Problems

Persistent Slabs

Persistent weaknesses are buried upwards of 150cm below the surface. Surprisingly large and destructive avalanches could be triggered naturally by the weight of additional snowfall, or by the energy of a person/sled.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible - Likely

Expected Size

3 - 7

Storm Slabs

The recent storm snow has consolidated into a cohesive slab. Extended sunny breaks may weaken the slab resulting in natural activity. Storm slab avalanches may step down to deeper weak layers.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Likely

Expected Size

2 - 6

Wind Slabs

Recent southwest wind and new snow have developed windslabs in the alpine and at treeline. These windslabs may take a few days to settle and bond.

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

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

2 - 5

Valid until: Mar 19th, 2012 9:00AM