Avalanche Forecast

Issued: Mar 10th, 2014 10:15AM

The alpine rating is considerable, the treeline rating is considerable, and the below treeline rating is moderate. Known problems include Storm Slabs, Deep Persistent Slabs and Loose Wet.

jlammers, Avalanche Canada

Cariboos.

The big storm may have passed, but elevated danger ratings will persist, especially with forecast warm temperatures. If the sun comes out, the avalanche danger may become HIGH.

Summary

Confidence

Fair - Timing or intensity of solar radiation is uncertain

Weather Forecast

We can expect a mix of sun and cloud for the forecast period as a ridge of high pressure pushes into the province. Ridgetop winds should remain light to moderate from the west-northwest. Freezing levels should sit at about 1500m on Tuesday, rising to about 1800m on Wednesday and then dropping back to about 1500m on Thursday.

Avalanche Summary

Several storm slab avalanches to size 2 were reported to have released on variety of aspects and elevations on Sunday. Numerous natural deep persistent slab avalanches to size 3 also occurred on the same day and stepped down to the February 10th interface. In a few isolated cases storm slab activity stepped down to basal facets at ground. Looking forward, another natural cycle may occur on solar aspects with forecast sunny breaks and warming.

Snowpack Summary

A storm slab which formed in recent days overlies small surface hoar crystals in sheltered areas and a sun crust on previously sun-exposed slopes. Wind and warming have created an "upside down" slab which may be particularly reactive where it overlies the buried crust. Rain at lower elevations has likely saturated much of the snowpack. Cornice development has also been significantThere is ongoing concern for a mix of weak surfaces which were buried on February 10th. This persistent interface lies about a metre below the surface, and includes weak surface hoar, well developed facets and a mix of hard surfaces which remain widespread at all aspects and elevations. Potential triggers at this point include a surface slab in motion, a large cornice fall, or intense solar warming.For the most part, the mid and lower snowpack are strong and well consolidated. Weak basal facets exist in some areas, but triggering is unlikely.

Problems

Storm Slabs

Recently formed storm slabs may become less likely to trigger, but solar warming may reactivate natural activity. Storm slabs may be particularly reactive where they overlie a buried crust. Cornices are now large and unstable.

Be cautious as you transition into wind affected terrain.>Be alert to conditions that change with elevation.>The new snow will require several days to settle and stabilize.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible - Likely

Expected Size

1 - 3

Deep Persistent Slabs

The early February weak layer may be stubborn to trigger, but long fracture propagations may still result if a large force such as a storm slab in motion or a cornice fall steps down to the persistent weak layer.

Avoid convexities or areas with a thin or variable snowpack.>Be aware of the potential for large, deep avalanches due to the presence of buried weak layers.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Unlikely - Possible

Expected Size

3 - 6

Loose Wet

Elevated freezing levels and the possibility of sun over the next few days will increase the chances of loose wet avalanches. A loose wet avalanche in motion may trigger deeper instabilities.

Avoid exposure to terrain traps where the consequences of a small avalanche could be serious.>Be cautious of wet sluffing in steep terrain.>Avoid sun exposed slopes when the solar radiation is strong, especially if snow is moist or wet.>

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

Elevations: All elevations.

Likelihood

Possible

Expected Size

1 - 3

Valid until: Mar 11th, 2014 2:00PM