Avalanche Forecast

Issued: Mar 29th, 2016 9:21AM

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

triley, Avalanche Canada

South Columbia.

Special Public Avalanche Warning for this region. Forecast very warm temperatures, high freezing levels, and strong solar radiation will increase the avalanche danger.

Summary

Confidence

High

Weather Forecast

Clear skies and very warm daytime temperatures are forecast for the remainder of the week; freezing levels should reach at least 2500 metres. Winds are expected to be light from the west or northwest. There should be some radiative cooling overnight that may develop surface crusts, but the warm air mass may break these crusts down very early in the day.

Avalanche Summary

On Monday some recent storm slab avalanches were reported releasing from skier triggering up to size 1.0 on north aspects in the alpine. Some natural cornice activity was also reported up to size 2.5 from northeast and easterly aspects in the alpine. Forecast very warm temperatures and high freezing levels are expected to increase natural cornice activity, and may trigger the buried persistent weak layers.

Snowpack Summary

Approximately 5-10 cm of snow fell on Sunday, which will probably be sun-affected on solar aspects and wind-affected in exposed terrain from forecast northerly winds. Approximately 40-50 cm of settled storm snow sits on a melt-freeze crust buried on Mar. 22. The late February persistent weak layer is an aspect dependant mix of surface hoar, facets and/or a thick crust down around 60-110 cm below the snow surface. Commercial operators continue to see hard sudden planar results in snowpack tests, which suggests that wide fracture propagations are possible. Cornices continue to be described as large and fragile. Expect loose wet avalanches and natural cornice falls with strong solar radiation and significant warming this week.

Problems

Cornices

Forecast high freezing levels, very warm daytime temperatures, and strong solar radiation are expected to result in natural cornice falls. Large cornice falls in motion may release deeply buried weak layers resulting in very large avalanches.

Do not travel on slopes that are exposed to cornices overhead.>

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

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

2 - 5

Loose Wet

High daytime temperatures and strong solar radiation may result in natural loose wet avalanches at all elevations. Avoid sun exposed slopes if the snow is moist or wet.

Be alert to conditions that change with elevation.>Avoid sun exposed slopes when the solar radiation is strong, especially if snow is moist or wet.>Avoid travelling in areas that have been reverse loaded by winds.>

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

Elevations: All elevations.

Likelihood

Likely

Expected Size

1 - 3

Persistent Slabs

Intense spring sun and rising temperatures could reactivate buried persistent weaknesses in the upper snowpack.

Be aware of the potential for large, deep avalanches due to the presence of buried surface hoar.>Use conservative route selection, stick to moderate angled terrain with low consequence.>Choose well supported terrain without convexities.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

3 - 6

Valid until: Mar 30th, 2016 2:00PM