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

Gale NW winds, lots of snow, and variable freezing levels mean the avalanche danger will be high on Tuesday, especially near the Divide

Stay out of avalanche terrain, and be aware of large paths near the divide which may run into the sub-alpine.

Avalanche problems

  • Wind Slabs

    • All elevations
    Likelihood
    Very Likely
    Size
    3

    With over a metre of new snow expected near the divide on Tuesday and gale NW winds, large windslab avalanches are likely on NE through to SW slopes in the alpine and high alpine. Gale winds can swirl around in valleys, building 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.

    Large avalanche paths near the divide could run into the sub-alpine. Pay attention to the terrain above you and avoid travel in these runouts.

  • Storm Slabs

    • All elevations
    Likelihood
    Likely
    Size
    2

    Intense snowfall and warming temperatures can make for denser snow falling onto lighter snow, creating a storm slab hazard. Expect to find an "upside down" snowpack anywhere that's sheltered enough to avoid windslab.

  • Loose Dry

    • All elevations
    Likelihood
    Very Likely
    Size
    1.5

    Loose snow avalanches are very likely out of steep terrain on Tuesday. These will be dry at higher elevations (above around 1800m) and wet below the rain-snow line. These could also trigger windslab and storm slab avalanches.

Recent Avalanche Activity

Observations from the 13th are limited due to bad weather, but natural avalanches are expected during this storm.

Prior to the storm, there was some small loose wet activity on sunny slopes over the weekend.

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

Current Snowpack Conditions

Around 30cm of new snow has fallen around the divide, tapering to 20cm on the Liebigs, and 10cm in the eastern part of the forecast area above 1500m. This has fallen with moderate NW winds which will have built deeper drifts in sheltered east and south facing slopes near ridgeline.

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

Rain, heavy and possibly thundery, with snow above 1600 metres. Easing to showers in the evening.

Wind at 1000 metres: Northerly gale 80 km/h, easing to northwesterly 40 km/h in the evening.

Wind at 2000 metres: Northwesterly severe gale 105 km/h, easing to gale 65 km/h in the evening.

Wind at 3000 metres: Northwesterly severe gale 120 km/h, easing to westerly severe gale 95 km/h late evening.

Freezing level: 1900 metres, lowering to 1600 metres at night.

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 confident a natural avalanche cycle will begin shortly after the arrival of the incoming weather.
  • We are uncertain due to variable freezing levels.

New Zealand Avalanche Advisory (NZ Mountain Safety Council)

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