Avalanche Forecast

Issued: Feb 16th, 2016 8:46AM

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

triley, Avalanche Canada

Purcells.

Persistent slab avalanches continue to be reported from the north of this region near Golden. Check out our new blog post.

Summary

Confidence

Moderate - Timing or intensity of solar radiation is uncertain

Weather Forecast

Overcast on Wednesday with flurries or light snow, light southerly winds, and freezing levels rising from valley bottoms overnight to about 1200 metres during the day. Overcast with light snow on Thursday combined with moderate southwest wind and freezing levels rising from valley bottoms up to 1300 metres. On Friday, sunny periods with scattered or broken clouds, moderate southwest winds, and freezing levels rising up to 1400 metres.

Avalanche Summary

On Tuesday we had reports of thin new windslabs that were skier controlled, and a size 2.5 deep persistent slab avalanche was reported that probably released on Monday on a west aspect in the alpine. On Monday we had reports of natural wind slab avalanches up to size 2.0, and one wind slab in the alpine that stepped down to a persistent week layer on an east aspect resulting in a size 3.0 avalanche.

Snowpack Summary

Approximately 10 cm of new snow arrived by Tuesday morning. Moderate to strong westerly winds transported the new snow into wind slabs in the alpine and at treeline. The new snow will overlie wind slabs which formed over the past few days. About 15-40 cm below the surface, you'll likely find a melt freeze crust which exists in most places except for in high elevation shaded terrain. In general there seems to be a reasonable bond between the crust and the overlying snow. I'd still keep an eye on this interface as it has become reactive on some features. The early January surface hoar/ facet layer is typically down 70-120 cm. Avalanche activity at this interface has tapered-off over the past week, but I'd be reluctant to trust this potentially destructive layer just yet. In general, the lower snowpack is well settled and strong, apart from some thin snowpack areas where basal facets exist.

Problems

Wind Slabs

Wind slabs may continue to be easy to trigger in the alpine and at treeline. This problem may result in wide propagations on easterly aspects where the recent storm snow is sitting on a supportive crust.

Travel on ridges to avoid freshly wind loaded features. >Be cautious as you transition into wind affected terrain.>

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

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1 - 3

Persistent Slabs

A recent size 3 persistent slab avalanche near Golden is a clear indication that deeply buried weaknesses cannot be trusted. Extra caution is required in the north of the region near Golden.

Be cautious around open slopes and convex rolls at and below treeline where buried surface hoar may be preserved. Big alpine features are also suspect.>Avoid thin, rocky or sparsely-treed slopes.>Avoid convexities or areas with a thin or variable snowpack.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Unlikely - Possible

Expected Size

3 - 5

Loose Wet

Recent storm accumulations may react as a loose wet avalanche in steep, sun-exposed terrain. Warming may also trigger destructive cornice falls.

Avoid sun exposed slopes when the solar radiation is strong, especially if snow is moist or wet.>

Aspects: North, North East, East.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 2

Valid until: Feb 17th, 2016 2:00PM