Avalanche Forecast

Issued: Jan 23rd, 2016 8:16AM

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

bcorrigan, Avalanche Canada

Purcells.

Extra caution should be used around tree line, especially in areas that have not seen a lot of recent traffic.A Special Public Avalanche Warning is in effect for this region

Summary

Confidence

Moderate - Forecast snowfall amounts are uncertain

Weather Forecast

A low pressure system will brush the southern part of the Province as it moves north eastward into Alberta Saturday afternoon and Sunday morning. The southern Purcells may receive 5 to 10cm of moist snow from this system . Freezing levels will fluctuate between 500 m overnight to 1000 min the afternoon on Sunday. Monday the freezing level will again rise to 1000 m with cloudy skies and a slight chance of flurries

Avalanche Summary

Numerous reports from yesterday of natural, skier remote, skier controlled and explosive result avalanches up to size 2.5. Most of these failed on a persistent weak layer 30 to 50 cm from the surface consisting of surface hoar or a crust/facet interface. Strong winds, new snow and rising temperatures increase likelihood of avalanches this weekend. Human triggering remains a real possibility through the forecast period.

Snowpack Summary

Conditions are variable across the Purcells. Wind slabs and storm slabs have developed at treeline and alpine elevations. In some areas, these overlie a surface hoar or crust/facet interface from early January and may be extra touchy. This persistent weak layer is around 30-60 cm down and may be just reaching tipping point in parts of the region. A more deeply buried layer of surface hoar from December is now considered dormant. In general, the mid and lower snowpack are well settled and strong.

Problems

Storm Slabs

Storm and wind slabs are particularly reactive around tree line and above, use great care venturing into new terrain at these elevations.

Choose conservative lines and watch for clues of instability.>Be cautious as you transition into wind affected terrain.>Travel on ridgetops to avoid wind slabs on slopes below.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Likely

Expected Size

1 - 4

Persistent Slabs

A small storm or wind slab avalanche may awaken this sleeping persistent slab and trigger a large, destructive avalanche

Be aware of the potential for remote triggers and wide propagations.>Avoid open slopes and convex rolls at and below treeline, and north-facing alpine slopes, where buried surface hoar may be preserved.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible

Expected Size

1 - 5

Valid until: Jan 24th, 2016 2:00PM