Avalanche Forecast

Issued: Apr 27th, 2014 8:32AM

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

jlammers, Avalanche Canada

Purcells.

We are no longer issuing danger ratings for this region due to a lack of field data.Please refer to this blog post for more insight into managing the current conditions.

Summary

Confidence

Poor - Due to the number of field observations

Weather Forecast

On Monday expect a mix of sun and cloud with a chance of isolated flurries. Winds should be mainly light from the northwest with freezing levels hovering around 1800m. On Tuesday and Wednesday a dry ridge of high pressure will bring mainly clear skies, light winds and freezing levels climbing upwards of 2500m by Tuesday afternoon.

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.The mid-February facet layer 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

New snow amounts are extremely variable across the region with the highest amounts falling in the south. Moderate winds have redistributed new snow and wind slabs may be found in lee features. Expect touchy conditions when the sun comes out.

Be cautious as you transition into wind affected terrain.>Avoid sun exposed slopes when the solar radiation is strong, especially if snow is moist or wet.>

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

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1 - 3

Loose Wet

Expect loose wet avalanches in steep terrain, especially if the sun comes out on Monday and 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: All elevations.

Likelihood

Possible

Expected Size

1 - 4

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 28th, 2014 2:00PM