Avalanche Forecast

Issued: Mar 29th, 2016 9:28AM

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

triley, Avalanche Canada

Purcells.

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

Some natural cornice falls were reported on Monday up to size 2.0. I suspect that avalanche activity will increase as the temperatures and freezing levels rise over the next few days.

Snowpack Summary

Forecast warming and strong solar is expected to result in loose wet avalanches on sun exposed aspects at all elevations. This warming trend may start to affect deeper snowpack layers each day. Surface crusts may break down early, and persistent weak layers may fail if the warming reaches their fragile structure. The late February surface hoar/crust layer is down 40-90 cm. This layer may continue to react to human triggers during periods of strong solar radiation and high daytime temperatures. Loose wet avalanches in motion, or cornice falls may step down to deeply buried weak layers. Cornices continue to be described as large and fragile, and may fail with forecast warming and strong sunshine this week. Conservative terrain without overhead hazard is a good strategy for avoiding the persistent slab problem.

Problems

Persistent Slabs

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

Avoid sun exposed slopes when the solar radiation is strong, especially if snow is moist or wet.>Be aware of the potential for large, deep avalanches due to the presence of a few different persistent weak layers.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

3 - 6

Cornices

Cornices may release naturally during periods of strong solar radiation and very warm daytime temperatures.

Do not travel on slopes that are exposed to cornices overhead.>Cornices become weak with daytime heating. >

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

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

3 - 6

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.

Avoid exposure to terrain traps where the consequences of a small avalanche could be serious.>

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

Elevations: All elevations.

Likelihood

Likely

Expected Size

1 - 3

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