Archived

Avalanche Forecast

Apr 19th, 2014–Apr 20th, 2014

Alpine

2: Moderate

Treeline

2: Moderate

Below Treeline

1: Low

Alpine

2: Moderate

Treeline

2: Moderate

Below Treeline

2: Moderate

Alpine

3: Considerable

Treeline

2: Moderate

Below Treeline

2: Moderate

Regions: South Rockies.

Check out this video by the CAC South Rockies field team describing current conditions and what to expect in the South Rockies and Lizard Range over the next couple of weeks. Please send us your observations at forecaster@avalanche.ca

Confidence

Poor - Due to the number of field observations

Weather Forecast

Sunday: Mix of sun and cloud / Light to moderate southwest winds / Freezing level at 2000 mMonday: Overcast skies / Moderate south winds / Freezing level at 2600 mTuesday: Moderate snowfall / Moderate southwest winds / Freezing level at 1900 m

Avalanche Summary

On Thursday, the CAC field team observed a natural cornice failure which triggered a thin slab below near Window Mountain in the Crowsnest Pass. There were also several loose wet avalanches from steep terrain. The team also saw the remnants of a natural deep persistent slab that broke several large mature trees. This avalanche probably occurred in the past week or so, and most likely during a warming event.

Snowpack Summary

Recent snowfall amounts probably vary throughout the region but I would expect there is around 15-30 cm in most places. During the last snowfall the snow line probably hovered between 1500 and 1700 m. The new snow is sitting on hard crust and may not bond well initially. Higher north aspects may have as much as 50 cm of settling dry powder. Cool overnight temperatures will likely form a new surface crust at lower elevations and on slopes that were exposed to sun. The deep facet/crust persistent weakness buried at the beginning of February (now down up to 80-100+ cm) should stay on your radar, especially on all alpine slopes during sunny periods. Any activity at this interface would be large and destructive. Also, give large sagging cornices a wide berth when traveling on or below corniced ridges.

Avalanche Problems

Wind Slabs

Wind slabs will have likely gained strength, but may still be sensitive to human triggering in steep, unsupported lee terrain.

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

Continued warming on Sunday will likely promote pushy loose wet avalanches. Watch for increased reactivity on steep, sun-exposed slopes.

Minimize exposure to sun exposed slopes when the solar radiation is strong.>Avoid exposure to terrain traps where the consequences of a small avalanche could be serious.>

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

Elevations: All elevations.

Likelihood: Likely

Expected Size: 1 - 2

Deep Persistent Slabs

The potential for deep persistent slabs will increase when the sun is shining and temperatures are warm. Minimize exposure to big alpine slopes when things are heating up.

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

Aspects: All aspects.

Elevations: Alpine.

Likelihood: Unlikely - Possible

Expected Size: 3 - 6