Avalanche forecast

Aoraki/Mt Cook

New Zealand Avalanche Advisory
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Avalanche danger

High Alpine · above 2,000 m
3 · Considerable
Alpine · 1,500 m–2,000 m
2 · Moderate
Sub Alpine · below 1,500 m
2 · Moderate
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Highlights

Reactive storm and windslabs may be encountered.

Below around 16-1800m new snow overlies a staunch rain crust. Any avalanching through this band may run further and with more momentum than expected.

New snow will need time to settle and bond-keep plans conservative.

Avalanche problems

  • Storm Slabs

    • All elevations
    Likelihood
    Possible
    Size
    2

    An estimated 100cm of new snow has fallen about the Divide, with around 40cm to the east as of Saturday morning. Winds were strong to gale NW but eased back over Friday, and finished much colder southerly. A change to very cold southerly winds will have shifted loading onto northerly aspects. Any storm snow instabilities should be healing and early observations tend to support this. Be sure to treat each slope with respect and check the bond within the new snow and to the old surface. The new snow has landed on a variety of snow surfaces; from hard crust to old stiff windslab and shallow powder in sheltered areas. The danger is considerable on the Divide above 2000m and moderate elsewhere.

  • Loose Dry

    • All elevations
    Likelihood
    Very Likely
    Size
    1.5

    Loose dry avalanching is very likely. As the day warms over Sunday expect this to transition to a loose wet problem on northern and western aspects, especially below 1700m where the old surface was frozen.

Recent Avalanche Activity

A natural avalanche cycle has taken place. Clouds parted Saturday afternoon, several size 2-3 slab avalanches were observed to have run above Sefton Bivi, and on Cadogan Peak. Likely others elsewhere.

Current Snowpack Conditions

Around 100cm of new snow is estimated to have fallen about the Divide since late Thursday, with 50cm at Mueller hut (1800m elevation), and around 60cm in the Liebig range. 20-40cm of new snow is expected to have reached eastern areas in the Cass. Winds were strong or gale NW initially but eased and turned much colder southerly. Snow has fallen to valley floor. Reports from Guides at Caroline Hut in the Mt Cook Range suggest a 'right side up' trend in the storm snow and non reactive to snowpack tests. This new snow overlies snowfall from earlier last week that was extensively distributed by gale NW and SW winds. Below around 1800m the older snowpack was capped with a hard rain crust which will provide a good sliding surface for any avalanching, (loose or slab), to gain momentum. Faceting has been observed in shallow snowpack areas. The lower snowpack appears to be well bonded, but we are continuing to monitor crust facet laminates in the lower pack in the eastern part of the forecast area.

Mountain Weather

Forecast (for Monday)

Fine, then a few showers developing in the evening. Snow lowering to 1200 metres at night.

Wind at 1000 metres

Southwesterly 30 km/h, dying out at night.

Wind at 2000 metres

Southwesterly 30 km/h, turning to northwesterly 35 km/h at night.

Wind at 3000 metres

Southwesterly 35 km/h.

Freezing level

300 metres, lifting to 1200 metres in the morning.

Sliding Danger

Exposed areas could be firm. Firm crusts may be hidden under new snow below 1600m.

Forecast Confidence

Moderate

  • We are uncertain due to a limited number of field observations.

New Zealand Avalanche Advisory (NZ Mountain Safety Council)

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