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
3 · Considerable
Sub Alpine · below 1,500 m
3 · Considerable
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Highlights

Heavy snowfall and strong NW winds are forecast over the weekend.

Large natural avalanches are likely where rain falls onto the existing snowpack, while heavy snowfall and strong winds rapidly load slopes.

Travel in avalanche terrain is not recommended this weekend.

Stay well clear of avalanche paths and runout zones.

Avalanche problems

  • Wind Slabs

    • All elevations
    Likelihood
    Likely
    Size
    2

    The wind slab problem is expected to increase as heavy snowfall and strengthening NW winds affect the region over the weekend.

    Up to 1 m of new snow is possible near the Main Divide. This new snow will fall onto well-developed near-surface facets, wind-pressed snow, or slick melt-freeze crust, creating potential weak layers and poor bonding.

    Large avalanches are likely. Stay clear of avalanche paths and avoid travelling through or beneath avalanche terrain.

  • Loose Wet

    • All elevations
    Likelihood
    Likely
    Size
    2

    Large loose wet avalanches are possible where precipitation falls as rain onto the existing snowpack.

    Temperatures are expected to fluctuate during the weekend storm, with uncertainty around how much temperatures will rise and fall. Rain may reach elevations as high as 2,000 m.

    These wet avalanches can be large, heavy, and destructive. Stay clear of avalanche paths and avoid travelling beneath steep slopes.

Recent Avalanche Activity

17 Aug: A skier triggered a Size 2 wind slab near Pioneer Hut at approximately 2300 m on a north-facing slope. See public observation.

16 Aug: Slab avalanching was generally confined to the recent storm snow, with one deeper slab observed on steep, unsupported NW-facing terrain on Mt Darwin at 2,700 m.16 Aug: Several Size 2 storm slabs were observed on south and southeast aspects in Twin Stream.

12 Aug: Heavy snow and rain overnight triggered a widespread cycle of wet loose and slab avalanches up to Size 3, mainly on south and east aspects.

Current Snowpack Conditions

Up to 30 cm of new snow fell overnight on 15 August, mainly in the southeast, with 5–10 cm on the Divide. Snow fell as low as 500 m. The new snow has generally bonded well to the old surface, with a cold clear night expected to further drying out the new snow.

Further west, a hard rain crust is still present around 2,000 m where less new snow fell. Deeper snowpack areas are generally strong, while shallow areas in the east have some faceting around crusts. This is not currently a major concern but could become reactive with a heavier load.

Mountain Weather

Rain, with heavy falls from morning. Snow to 1400 metres until afternoon.

Wind at 1000 metresNorthwesterly gale 70 km/h, easing to 50 km/h for a time in the afternoon and evening.

Wind at 2000 metresNorthwesterly severe gale 90 km/h.

Wind at 3000 metresNorthwesterly severe gale 100 km/h.

Freezing level1700 metres, lifting to 2000 metres for a time in the afternoon and evening.

Sliding Danger

Crampons and ice axe are useful at the moment for alpine travel. The firm rain crust is now buried by snowfall. In steep terrain or where the new snow is shallow this may be an issue underfoot or ski.

Forecast Confidence

Moderate

  • We are uncertain about forecast precipitation amounts.
  • We are uncertain due to rapidly changing freezing levels.

New Zealand Avalanche Advisory (NZ Mountain Safety Council)

Regions covered