Avalanche Forecast

Issued: Apr 25th, 2014 9:10AM

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

mbender, Avalanche Canada

Purcells.

Avalanche danger can rise quickly with daytime warming and solar radiation. Be aware of changing conditions and overhead hazards.

Summary

Confidence

Poor - Due to the number of field observations

Weather Forecast

Synopsis: Unsettled weather will persist throughout the forecast period as a series of fronts slowly move across the province.Saturday: Flurries / Light southerly winds / Freezing levels 1800m.Sunday: Flurries /Light southwesterly winds / Freezing levels 1800-2000m.Monday: Mix of sun and cloud / Light southwesterly winds / Freezing level 2100m.

Avalanche Summary

Expect loose wet avalanches in steep terrain if it is raining or during sunny periods, especially if the sun or rain is affecting fresh snow. Spring squalls may bring locally heavy precipitation and new storm or wind slabs may develop in higher terrain if you see significant new snow accumulation. Cornices collapses have been reported during periods of daytime warming. Occasionally these heavy triggers have caused large deep slab avalanches on the slopes below.

Snowpack Summary

This is a broad general summary of conditions in the region. This summary is based on limited field data and should be supplemented with local observations to help assess avalanche danger.Over the past week or so the Purcells have seen moderate amounts of new snow mixed with showers or periods of rain below 1600-1800 m. Southerly winds have likely formed pockets of wind slab at higher elevations in lee of ridges and terrain features. The upper snowpack generally consists of layers of moist and/or dry snow mixed with several well bonded crusts.Several 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 80 - 180cm. 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.- Weak basal facets can be found in many areas, however triggering this layer is unlikely.

Problems

Wind Slabs

Moderate winds have redistributed recent snow and wind slabs may be found in lee features.

Be cautious as you transition into wind affected terrain.>

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

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 3

Loose Wet

Expect loose wet avalanches in steep terrain if it is raining or during sunny periods, especially if the sun or rain is affecting fresh snow.

Avoid sun exposed slopes when the solar radiation is strong, especially if snow is moist or wet.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

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, warming temperatures or a smaller wet or wind slab 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.>Give cornices a wide berth when travelling on or below ridges.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Unlikely

Expected Size

3 - 6

Valid until: Apr 26th, 2014 2:00PM