Avalanche Forecast

Issued: Mar 24th, 2016 9:14AM

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

triley, Avalanche Canada

South Columbia.

Sunny weather returning after a brief storm. Watch for new storm slabs on dry shaded aspects and loose wet snow on solar aspects. Expect natural cornice falls due to sun and daytime warming.

Summary

Confidence

Moderate - Timing or intensity of solar radiation is uncertain

Weather Forecast

Snow ending overnight or early Friday morning, with cloud breaking up and becoming scattered in the afternoon. Periods of strong solar radiation with freezing levels climbing up to at least 1500 metres and light westerly winds. Expect a good freeze down close to valley bottoms on Saturday morning. Light southwest winds and mostly sunny skies during the day, high cloud developing in the late afternoon. Freezing levels climbing up to 1700 metres. On Sunday, expect mostly cloudy conditions with flurries or light snow by the afternoon.

Avalanche Summary

No new reports of persistent slab avalanches. On Wednesday we had reports of loose wet solar induced activity in most areas up to size to size 2.0, as well as some thin wind slabs in the high alpine on shaded aspects. I suspect that the new storm slab was reactive to human triggering on Thursday. New storm slabs may continue to be triggered on shaded aspects, and storm snow may release as loose wet avalanches on solar aspects.

Snowpack Summary

Forecast new snow and wind is expected to develop new storm slabs above a mix of surfaces, including crusts on solar aspects, moist snow up to treeline, and dry snow or recent wind slabs in the alpine on shaded aspects. Cornices continue to be described as large and fragile. The late February persistent weak layer is an aspect dependant mix of surface hoar, facets and/or a thick crust down around 60 to 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. New storm loading above the buried persistent weak layer may increase the likelihood of triggering large avalanches.

Problems

Storm Slabs

New storm slabs may be easy to trigger on shaded aspects. Storm snow may release as loose wet avalanches on solar aspects during periods of clear and sunny weather.

Be alert to conditions that change with elevation.>Avoid freshly wind loaded features.>Avoid sun exposed slopes when the solar radiation is strong, especially if snow is moist or wet.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1 - 4

Persistent Slabs

The persistent weak layer of buried surface hoar, facets, and crusts is buried down close to a metre. This has become a low probability of triggering, but high consequence of large avalanche problem. Choose well supported terrain without convexities.

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

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Unlikely

Expected Size

3 - 6

Cornices

Natural cornice falls are likely during periods of strong solar radiation and warm daytime temperatures. Cornice falls may trigger deeply buried persistent weak layers.

Extra caution needed around cornices with current conditions.>Do not travel on slopes that are exposed to cornices overhead.>

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

Elevations: Alpine, Treeline.

Likelihood

Likely

Expected Size

3 - 5

Valid until: Mar 25th, 2016 2:00PM