Avalanche Forecast

Issued: Mar 24th, 2016 9:28AM

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

Cariboos.

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 avalanches reported. On Tuesday, we had a report of a natural slab avalanche size 2.5 on a southwest aspect at 2200 metres with a wide propagation and depth of about 100 cm, the bed surface was sun-crust with melted surface hoar on top. Solar induced loose wet avalanches up to size 2.0 were reported on Monday and Tuesday.

Snowpack Summary

Forecast new snow and wind is expected to develop new storm slabs at all elevations. Daytime warming continues to melt surface snow, and overnight crust recovery has been variable depending on cloud cover. Large cornices loom over many ridge lines and many are teetering on the brink of failure. Old wind slabs may remain a problem on high elevation north facing features. The make up of the late February persistent weak layer is an aspect dependant mix of surface hoar, facets and/or a thick crust down around 70 to 100 cm below the snow surface. Large triggers like natural cornice fall and explosive control work continue to initiate avalanches failing on this interface. The recent warm to cool temperatures should give the overlying slab a bit of strength, but it has yet to prove itself trustworthy. Unfortunately there's not much of a reliable pattern telling us what exact aspects are most suspect. As a precautionary measure, we recommend remaining suspicious of steep unsupported features at and above treeline.

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.

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.

Avoid steep slopes below cornices.>Extra caution needed around cornices with current conditions.>

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

Elevations: Alpine, Treeline.

Likelihood

Likely

Expected Size

2 - 4

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