Avalanche forecast

Aoraki/Mt Cook

New Zealand Avalanche Advisory
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Avalanche danger

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

With plenty of new snow and wind in the last 48 hours, the avalanche danger remains high for Wednesday, especially near the Divide.

Stay out of avalanche terrain, and give the new snow some time to settle.

Avalanche problems

  • Wind Slabs

    • All elevations
    Likelihood
    Very Likely
    Size
    3

    Large windslab avalanches are still likely on NE through to SW slopes in the alpine and high alpine, with the possibility of large paths near the divide running into thesub- alpine. Gale winds may have built windslab mid-slope or in unexpected areas. Stay out of avalanche terrain until the storm passes.

    Snowfall totals will be lower away from the divide, but winds and warming temperatures could still build significant slabs and dangerous avalanche conditions.

    A southwesterly change on Wednesday afternoon could see new slabs building on northerly aspects above 1800m.

  • Storm Slabs

    • All elevations
    Likelihood
    Likely
    Size
    2

    Storm slab avalanches in sheltered areas are still likely as snowfall and temperature fluctuations continue through Wednesday.

  • Loose Dry

    • All elevations
    Likelihood
    Likely
    Size
    1

    Loose snow avalanches are likely out of steep terrain on Wednesday. These will be dry at higher elevations (above around 1900m) and wet below the rain-snow line. These could also trigger windslab and storm slab avalanches.

Recent Avalanche Activity

Observations are still limited by bad weather, but two size 3 suspected wind slab avalanches were visible from Aoraki Mt Cook Village on SE facing slopes in the Hayter and Stewart Stream drainages off the Divide on the 14th.

There was also a widespread loose wet avalanche cycle below 1800m.

Please let us know via the Public Observations link if you see any slides.

Current Snowpack Conditions

Around 1m of new snow has fallen around the divide, tapering to 70cm on the Liebigs, and 20cm in the eastern part of the forecast area above 1800m. This has been redistributed by gale NW winds which will have built deeper drifts in sheltered east and south facing slopes. Freezing levels have fluctuated from between around 1500m and 2000m, leaving wet snow at lower elevations and density inversions in the storm snow in the Alpine and High Alpine.

This sits on a well settled snowpack, with as much 2m of snow near the divide, tapering to 120cm at upper elevations in the Liebig, Gammack and Burnett Mountains, tapering to roughly 50cm at 1700m.

In the eastern part of the forecast area, this snowpack was capped with a variable rime crust around 1cm thick, with another crust down around 6cm. Any surface hoar that developed during the cold, clear conditions on the weekend has probably been destroyed by gale NW winds on Monday morning, but faceting below these two crusts has probably survived. We are monitoring these layers to see how they respond to new load during this storm.

Mountain Weather

Isolated showers turning to rain, possibly heavy, for a time in the morning and afternoon. Snow above 1500 metres until evening.

Wind at 1000 metres: Northwesterly 40 km/h, rising to gale 70 km/h in the morning, easing to southwesterly 30 km/h in the afternoon.

Wind at 2000 metres: Northwesterly 55 km/h, rising to gale 80 km/h in the morning, easing to westerly 40 km/h in the evening.

Wind at 3000 metres: Northwesterly severe gale 95 km/h, easing to westerly gale 70 km/h in the afternoon

Freezing level: 1600 metres, lifting to 1900 metres for a time in the afternoon.

Sliding Danger

Exposed areas will likely be stripped back to a slick crust by strong NW winds on Monday morning. Take an ice axe and crampons for any travel in the high alpine or ridge travel at lower elevations.

Forecast Confidence

Moderate

  • We are confident the likelihood of avalanches will increase with the forecast weather.
  • We are uncertain due to a limited number of field observations.
  • We are uncertain due to variable freezing levels.

New Zealand Avalanche Advisory (NZ Mountain Safety Council)

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