Avalanche Forecast

Issued: Feb 13th, 2016 8:12AM

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

jlammers, Avalanche Canada

Purcells.

Triggering large avalanches is still possible, especially in the north of the region. Remain diligent and continue to make conservative decisions.

Summary

Confidence

Moderate

Weather Forecast

A series of weak systems will pass through the region over the forecast period. Expect 5-10cm of new snow on Sunday afternoon, a mix of sun and cloud on Monday and an additional 5-10cm of snow on Tuesday. Ridgetop winds will be extreme from the southwest on Sunday afternoon, strong and northwesterly on Monday, and strong and southwesterly on Tuesday. Freezing levels should hover around 1700m for the forecast period.

Avalanche Summary

A natural Size 1.5 avalanche was observed in the Golden Backcountry on Thursday that apparently ran on a reloaded bed surface in a wind loaded feature. The interface is suspected to be the early January weak layer. Natural persistent slab avalanche activity was also observed earlier in the week, with a report of two Size 2.5s also in the Dogtooth Range that also released on the surface hoar, facet and crust weakness as deep as a meter down.

Snowpack Summary

A supportive crust (in most places aside from shaded aspects at treeline elevations) and perhaps new surface hoar (where it survived the heat, rain and sun) could be buried by as much as 5-10cm of fresh snow or deeper wind slabs. The early January surface hoar/ facet layer is typically down 70-90 cm. Recent avalanches have been failing on this interface in the north of the region (see avalanche discussion) and it continues to produce sudden planar results in snow pit tests. In general, the lower snowpack is well settled and strong, apart from some thin snowpack areas where basal facets exist.

Problems

Wind Slabs

Touchy fresh pockets of wind-deposited snow may be lurking on the downwind side of ridgecrests and terrain features. Expect them to get bigger and touchier throughout the day on Sunday.

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

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

Elevations: Alpine, Treeline.

Likelihood

Likely

Expected Size

1 - 2

Persistent Slabs

A weak mix of surface hoar and facets remain a concern, especially in the Dogtooth Range in the north of the region. A cautious approach is required in this area, as this layer may still surprise with nasty consequences.

Avoid convexities or areas with a thin or variable snowpack.>Avoid thin, rocky or sparsely-treed slopes.>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.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible

Expected Size

3 - 5

Valid until: Feb 14th, 2016 2:00PM