Avalanche Forecast

Issued: Mar 6th, 2016 9:16AM

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

triley, Avalanche Canada

Cariboos.

Storm slabs continue to be a concern. Wide fracture propagations are possible where the storm snow is sitting on a weak buried layer of surface hoar.

Summary

Confidence

Moderate - Freezing levels are uncertain

Weather Forecast

A clearing and cooling trend should bring freezing levels down to valley bottoms overnight. A mix of sun and cloud on Monday with periods of light precipitation and moderate westerly winds. A mix of sun and cloud on Tuesday with light winds. A diurnal freeze/thaw cycle setting up with freezing down to valley bottoms overnight and then rising up to 1500 metres during the day. No change for Wednesday, but a new system moving into the region on Wednesday night.

Avalanche Summary

Natural avalanches continued to release down 40-60 cm on Friday up to size 2.5, and on Saturday up to size 3.0. Reports from Thursday that several natural size 2.0 slab avalanches and one size 3.0 storm slab were suspected to have released on the late February surface hoar layer. There was also a report of a size 3.0 avalanche remotely triggered by a skier that was 20 metres away.

Snowpack Summary

New snow continues to develop the storm slab that is 40-60cm thick and bonding poorly to a crust on previously sun-exposed slopes and surface hoar (February 27th or late February) on shady and sheltered slopes. Thicker and touchier wind slabs are lurking throughout exposed terrain at and above treeline. A couple of sun crusts might exist in the upper 50-70cm on southerly aspects. The surface hoar and/or crust layer which was buried February 10 is now down around a metre and is still producing isolated hard sudden results in snowpack tests. Large cornices will be getting weak with warmer temperatures.

Problems

Storm Slabs

Storm slabs may continue to be triggered by light additional loads at treeline and in the alpine. Dropping freezing levels may develop a crust at lower elevations where the surface was moist or wet.

Be cautious as you transition into wind affected terrain.>The new snow will require several days to settle and stabilize.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Likely

Expected Size

1 - 4

Persistent Slabs

The persistent weak layer of surface hoar may continue to be triggered by large loads like re-grouping or cornice falls.

Choose well supported terrain without convexities.>Be aware of the potential for large, deep avalanches due to the presence of buried surface hoar.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Likely

Expected Size

2 - 5

Cornices

Fresh cornice growth may fall off naturally due to daytime warming.

Extra caution needed around cornices with current conditions.>Cornices become weak with daytime heating. >

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

Elevations: Alpine.

Likelihood

Possible

Expected Size

2 - 5

Valid until: Mar 7th, 2016 2:00PM