Avalanche Forecast

Issued: Mar 14th, 2017 4:53PM

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

rbuhler, Avalanche Canada

South Coast.

On Wednesday, touchy storm slabs are expected in the high alpine. Extra caution is also required on all sun exposed slopes if the sun comes out in full force.

Summary

Confidence

Low - Due to the number of field observations

Weather Forecast

Wednesday is currently expected to be mainly dry with a chance of sunny breaks. Alpine wind is expected to be light to moderate from the southwest and freezing levels are expected to be around 1300 m. The next pulse of precipitation is expected to arrive Wednesday overnight or Thursday morning and 30-40 mm is currently forecast between Thursday morning and Friday morning. Ridgetop wind is expected to be moderate from the southwest on Thursday with freezing levels around 900 m. Friday is currently forecast to be mainly dry with the next storm system arriving Friday overnight or Saturday morning.

Avalanche Summary

No new avalanches have been reported, but it should be noted that the warm, stormy weather has been discouraging backcountry travel and obscuring visibility into alpine terrain so observations have been very limited.On Wednesday, stability is generally expected to improve as temperatures drop. However, if the sun comes out, it can quickly destabilize the snowpack on sun exposed slopes. In the high alpine above the rain line, any recent storm snow is expected to remain touchy, especially in wind loaded terrain.

Snowpack Summary

Heavy rain has saturated the upper snowpack at all but high alpine elevations after roughly 50mm of precipitation fell over Sunday night and Monday morning. Any new snow that may have accumulated at high alpine elevations is likely to remain reactive to human triggering over the short term. At higher elevations, lingering potential may exist for loading from rain or snow to promote reactivity at the late February interface, roughly 1.5 metres deep. This layer is composed of a sun crust on southerly aspects and surface hoar on shaded aspects. An avalanche on this layer would be large and very destructive. No concerns exist below this interface and the snowpack at treeline and below is generally well settled and strong.

Problems

Storm Slabs

In the high alpine, recent storm snow may be touchy on Wednesday, especially in wind loaded terrain. Extra caution is also needed around cornices right now.

Be alert to conditions that change with elevation.Avoid freshly wind loaded features.Give cornices a wide berth when travelling on or below ridges.

Aspects: All aspects.

Elevations: Alpine.

Likelihood

Possible - Likely

Expected Size

1 - 2

Loose Wet

If the sun comes out in full force, expect sluffing from steep sun exposed slopes. Cornices will also become weak with prolonged sun exposure.

Be cautious of sluffing in steep terrain.Minimize exposure to steep, sun exposed slopes when the solar radiation is strong.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible - Likely

Expected Size

1 - 2

Persistent Slabs

A weak layer down around 1.5 metres is creating a low probability/high consequence scenario. While it is unlikely to directly trigger this layer, a small avalanche or cornice fall could step down to it.

Be aware of the potential for very large avalanches due to deeply buried weak layers.If triggered, storm slabs may step down to deeper layers resulting in very large avalanches.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Unlikely - Possible

Expected Size

2 - 4

Valid until: Mar 15th, 2017 2:00PM