Avalanche Forecast

Issued: Apr 7th, 2013 10:11AM

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

ghelgeson, Avalanche Canada

Purcells.

Summary

Confidence

Fair - Intensity of incoming weather is uncertain on Wednesday

Weather Forecast

Synopsis: A ridge builds into the region Monday followed by a moderate system Tuesday night. A strong zonal flow sets up in the wake of the Tuesday night storm.Monday: Freezing Level: 1500m. Precip: 2/4mm â€“ 2/6cm Wind: Light, South.Tuesday: Freezing Level: 1800m Precip: 8/15mm â€“ 8/25cm (overnight) Wind: Mod, WWednesday: Freezing Level: 1900m Precip: Convective flurries. Wind: Light, South.

Avalanche Summary

Natural avalanches up to size 1.5 have been running in the recent storm snow.Â In the south of the region natural wet loose avalanches to size 2 were observed on NW-NE facing slopes at 2000m.

Snowpack Summary

At upper elevations 15-40cm of new snow is covering a crust or moist snow. In some places in the alpine and at treeline this new snow may have buried a recently formed layer of surface hoar or facets. At many lower elevations (below 2000m) warm temperatures have created a snowpack that is almost entirely isothermal. New snow combined with wind will has made large cornices even bigger.The March 10th surface hoar/crust interface is buried more than 100cm in most places. Although unlikely to trigger, this deep persistent weakness remains a concern because of the potential for very large avalanches particularly with heavy triggers such as cornice falls or lighter triggers on solar aspects where the crust is more prevalent. Below this the snowpack is strong and well settled.

Problems

Wind Slabs

Wind slabs are likely growing old and tired but they may still be a problem on high elevation lee slopes. The large cornices that loom over many slopes may fail with daytime heating/solar input.

Be cautious as you transition into wind affected terrain.>Use ridges or ribs to avoid pockets of wind loaded snow.>Give cornices a wide berth when travelling on or below ridges.>

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

Elevations: Alpine.

Likelihood

Possible

Expected Size

1 - 5

Loose Wet

Conditions at and below treeline change radically with air temperature and solar input this time of year. Daytime heating and direct sun will likely be followed by another round of loose snow avalanches.

Make your travel plans to take advantage of overnight freezing.>Take advantage of cooler parts of the day if you're planning bigger objectives or plan to travel under large avalanche paths.>Watch for wet loose or slab activity with forecast warm temperatures.>Avoid exposure to terrain traps where the consequences of a small avalanche could be serious.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 4

Valid until: Apr 8th, 2013 2:00PM