Avalanche Forecast

Issued: Apr 19th, 2014 9:24AM

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

esharp, Avalanche Canada

Purcells.

Avalanche danger can quickly rise above what is forecast with warming temperatures and/or brief periods of sun. Be aware of changing conditions and overhead hazards.For more insight into spring danger ratings, check out our Blog Post.

Summary

Confidence

Fair - Due to the number of field observations

Weather Forecast

Synopsis: A weak ridge of high pressure will develop over the interior of the province Sunday. Convective flurries may be possible. The ridge shifts eastward as the next system moves in over the region Monday night.Tonight and Sunday: Light precipitation overnight (up to 10cm) then clearing / Moderate then light westerly winds / Freezing levels 2000mMonday: Partly cloudy with a chance of flurries / Moderate southwesterly winds / Freezing levels up to 2600m Tuesday: Flurries (5-20 cm) / Light southerly winds / Freezing levels between 1900 and 2500m

Avalanche Summary

At lower elevations and on solar aspects small to large loose wet avalanche continue to be triggered on steep slopes. Cornices collapses have been reported during periods of daytime warming. Occasionally these heavy triggers have caused larger deep slab avalanches on the slopes below.

Snowpack Summary

5-30 cm of recent storms snow is rapidly settling and appears to be bonding well to a supportive crust that can be found on all aspects and elevations except for high elevation north-facing terrain. Soft winds slabs may be found in the immediate lee of ridges and ribs.Three persistent weak layers still exist in the highly variable snowpack of the Purcells: The mid-March sun crust/surface hoar layer down 50-80cm and the early-March crust/facet/surface hoar layer down around 80-120cm seem to be laying dormant for the time being. The mid-February crust/facet/surface hoar combo is typically down 60 - 120cm. Direct triggering of this layer has become unlikely, however, cornice fall, a smaller avalanche in motion or prolonged warming may wake this layer up. The resulting avalanche would be very large and destructive.At the base of the snowpack weak basal facets can be found in many areas, however triggering this layer is unlikely.

Problems

Loose Wet

Expect to see an increase in avalanche activity at lower elevations or on solar aspects if the sun comes out for extended periods of time.

Avoid sun exposed slopes when the solar radiation is strong, especially if snow is moist or wet.>Cornices become weak with daytime heating. >

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 3

Wind Slabs

Wind slabs immediately lee of ridge crest may be sensitive to human triggering.

Be careful with wind loaded pockets, especially near ridge crests and roll-overs.>

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

Elevations: Alpine.

Likelihood

Unlikely - Possible

Expected Size

1 - 3

Deep Persistent Slabs

The potential for very large deep slab avalanches needs to remain on your radar. Cornice fall, strong sun, warming temperatures or a surface avalanche in motion could act as triggers.

Be aware of the potential for very large, deep and destructive avalanches due to the presence of deeply buried persistent weak layers.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Unlikely - Possible

Expected Size

3 - 6

Valid until: Apr 20th, 2014 2:00PM