Archived

Avalanche Forecast

Apr 23rd, 2014–Apr 24th, 2014

Alpine

2: Moderate

The avalanche danger rating in the alpine will be moderate

Treeline

2: Moderate

The avalanche danger rating at treeline will be moderate

Below Treeline

1: Low

The avalanche danger rating below treeline will be low

Alpine

2: Moderate

The avalanche danger rating in the alpine will be moderate

Treeline

2: Moderate

The avalanche danger rating at treeline will be moderate

Below Treeline

1: Low

The avalanche danger rating below treeline will be low

Alpine

2: Moderate

The avalanche danger rating in the alpine will be moderate

Treeline

2: Moderate

The avalanche danger rating at treeline will be moderate

Below Treeline

1: Low

The avalanche danger rating below treeline will be low

Regions: Purcells.

This forecast was build on limited field reports. If you head out into the mountains please tell us about the conditions you found. Send your observations to [email protected]

Confidence

Fair - Due to the number of field observations

Weather Forecast

Synopsis:Â Unsettled weather will persist throughout the forecast period .Tonight and Thursday: Sunny with cloudy periods and chances of flurries / Light southerly winds / Freezing levels 2000mFriday: Flurries / light southeasterly winds / Freezing levels 2000mSaturday: Flurries / Light southwesterly winds / Freezing levels 2000m

Avalanche Summary

Small slabs have been recently triggered naturally and by skiers in areas where the upper snow is moist and sits above a crust. 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 large deep slab avalanches on the slopes below.

Snowpack Summary

A recent crust on all but high elevation North aspects is now buried by up to 10cm of new snow. Below this 10 to 30cm of snow overlies older melt-freeze crusts from earlier in the month. Wind slabs can be found in lee features on N and E aspects in the Alpine.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 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.- Weak basal facets can be found in many areas, however triggering this layer is unlikely.

Avalanche Problems

Wind Slabs

Moderate winds have redistributed recent snow and wind slabs may be found in lee features on North aspects. Below 2200m these slabs may be sitting on a recent melt freeze crust.

The new snow will require several days to settle and stabilize.>Be cautious as you transition into wind affected terrain.>

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

Elevations: Alpine, Treeline.

Likelihood: Possible

Expected Size: 1 - 3

Loose Wet

A supportive melt freeze crust can be found at lower elevations. This crust could break down rapidly if the sun comes out

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

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood: Possible - Likely

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