Avalanche Forecast

Issued: Feb 23rd, 2013 8:50AM

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

Peter, Avalanche Canada

Northwest Inland.

Summary

Confidence

Fair - Intensity of incoming weather is uncertain

Weather Forecast

Synopsis: The active weather pattern continues into next week with a series of frontal systems affecting the region with short breaks in between each pulse.Overnight and Sunday: The first system arrives late Saturday bringing 5-10 cm overnight, and an additional 5-10 cm on Monday morning. The freezing level is around 800 m and winds are moderate to strong from the southwest. Monday: Cloudy with sunny breaks. The freezing level is near valley bottom and winds ease to light from the northeast. Tuesday: The next system arrives bringing more cloud and light snow with increasing winds.

Avalanche Summary

There are no new reports of avalanches; however, observations have been limited due to poor visibility and weather.

Snowpack Summary

Around 30 cm of new snow has fallen in the past couple days. This new snow was accompanied by strong southwest winds forming wind slabs in exposed terrain in lee of ridges, in gullies, and behind terrain features. There are a variety of old interfaces now down 40 - 100cm which include facets, crusts and isolated pockets of surface hoar. There is very limited information about the nature of this interface. I would stress the importance of digging down to find and test weak layers before committing to larger and steeper slopes.A strong mid-pack currently overlies a weak base layer of facets/depth hoar. It is worth noting that the snowpack in general is quite shallow compared to averages; triggering the basal weakness may still be possible from thin spots, rocky outcrops or under the weight of larger triggers such as cornice fall.

Problems

Wind Slabs

New snow has been redistributed into dense wind slabs in exposed lee terrain and cross-loaded gully features. Triggering is likely on steep wind loaded slopes.

Be cautious as you transition into wind affected terrain.>Highmark or enter your line well below ridge crests to avoid wind loaded pillows.>Whumpfing, shooting cracks and recent avalanches are all strong indicators of an unstable snowpack.>

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

Elevations: Alpine, Treeline.

Likelihood

Likely

Expected Size

1 - 4

Persistent Slabs

Buried beneath the new snow sits a surface hoar/crust/facet weakness down 50 - 100 cm. This may be sensitive to rider triggering in steeper sheltered terrain or over convex rolls, especially at treeline elevations.

Avoid open slopes and convex rolls at and below treeline where buried surface hoar may be preserved.>Avoid convexities or areas with a thin or variable snowpack.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible

Expected Size

1 - 5

Valid until: Feb 24th, 2013 2:00PM