Archived

Avalanche Forecast

Apr 2nd, 2016–Apr 3rd, 2016

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

3: Considerable

The avalanche danger rating in the alpine will be considerable

Treeline

3: Considerable

The avalanche danger rating at treeline will be considerable

Below Treeline

2: Moderate

The avalanche danger rating below treeline will be moderate

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

2: Moderate

The avalanche danger rating below treeline will be moderate

Regions: South Coast.

Extra caution is still required around and below cornices. Avoid sun-exposed slopes if the sun makes an appearance on Sunday.

Confidence

Moderate

Weather Forecast

Increased cloud will develop throughout Sunday with 10-20cm of new snow expected between Sunday night and Monday morning. A mix of sun and cloud and occasional light flurries are forecast for the rest of the period. Ridgetop winds should be moderate from the southwest with Sunday night's system and then become light. Freezing levels should sit at 2000m on Sunday, 1600m on Monday and 1500m on Tuesday.

Avalanche Summary

In recent days, natural cornice releases and explosives control triggered size 2.5 persistent slabs in the Duffey area. A few size 2 wet slabs were also reported. Lots of loose wet sluffing was also observed. Cooling temperatures on Saturday will mean that natural sluffing and cornice releases will become less likely, but with all the heat in the snowpack, it will still be possible for human-triggering of cornices. It may still be possible for a cornice release to trigger a deep weakness in the north of the region. Once the snow surface develops a widespread supportive crust layer, it will become unlikely to trigger any deep weaknesses.

Snowpack Summary

A melt-freeze cycle is reported to be widespread to mountaintops except for shaded true north aspects above 2200m. The last few nights have seen some limited overnight crust formation which has quickly broken down the following morning. With freezing levels dropping on Saturday, a surface crust has likely formed at higher elevations and hasn't completely broken down during the day. Large cornices are lingering above many alpine slopes. Below the snow surface, there is a layer of concern in the northern half of the region. Professionals are tracking a thick layer of facets down over 1m which likely resulted in a couple deep persistent avalanches which were reported on Thursday. Deep persistent weaknesses and natural cornice failures will remain a concern until there is a substantial period of cooling.

Avalanche Problems

Cornices

Lingering cornices are not expected to fail naturally once the temperature drops but may remain reactive to human-triggering. Use extra caution around cornices until the region sees substantial cooling and refreeze.

Cornices become weak with daytime heating, so travel early on exposed slopes. >Extra caution needed around cornices with current conditions. >Give cornices a wide berth when traveling on or below ridges. >

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

Elevations: Alpine, Treeline.

Likelihood: Possible

Expected Size: 1 - 5

Loose Wet

As temperatures drop and cloudy skies develop, loose wet avalanches will become less likely. If the sun makes an appearance on Sunday, use extra caution in sun-exposed terrain.

Avoid sun exposed slopes when the solar radiation is strong, especially if snow is moist or wet. >Start and finish early before the surface crusts melt. >Be cautious of sluffing in steep terrain.>

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

Elevations: All elevations.

Likelihood: Possible

Expected Size: 1 - 2

Deep Persistent Slabs

There is concern that buried weak layers may wake-up with the warming this week, especially in the northern half of the region. Pros are tracking a facet layer down over 1m. Very large avalanche may be possible in isolated areas.

Cornice releases have the potential to trigger deeply buried weak layers. >Avoid sun exposed slopes when the solar radiation is strong, especially if snow is moist or wet. >Be aware of the potential for large, deep avalanches due to the presence of buried weak layers. >

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood: Unlikely - Possible

Expected Size: 3 - 6