Avalanche forecast

Tongariro

New Zealand Avalanche Advisory
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Avalanche danger

High Alpine · above 2,300 m
3 · Considerable
Alpine · 1,800 m–2,300 m
2 · Moderate
Sub Alpine · below 1,800 m
2 · Moderate
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Highlights

Wind slabs are likely to develop as new snow begins to be transported to south aspects. At lower elevations, rain will weaken the surface snow, creating a loose wet avalanche hazard. The weather will be unpleasant over the next 24 hours. Poor visibility and showers make identifying alpine hazards difficult. Recommend delaying alpine travel until the conditions improve.

Avalanche problems

  • Wind Slabs

    • All elevations
    Likelihood
    Likely
    Size
    2

    Wind slabs will form on south-facing aspects as new snow accumulates and is redistributed. Any loose material will be transported to south-facing aspects above 1900 metres elevation. This wind slab hazard may become reactive to light loads at the higher elevations. The location of these deposits will be on terrain features such as rocky outcrops and near ridgelines, which act as catchments. Triggering these wind slabs will be more likely on steep, extreme, unsupported slopes.

  • Loose Wet

    • All elevations
    Likelihood
    Possible
    Size
    2

    Loose wet avalanche activity will increase as snowpack saturation eventuates. Rain will continue to weaken the surface snow, increasing the likelihood of triggering avalanches on steep slopes. This will eventually affect the surface structure, breaking down the surface layers. Watch for signs such as rollerball and pinwheel activity.

Recent Avalanche Activity

No natural or human-triggered avalanche activity has been reported or observed over the past 24 hours.

Current Snowpack Conditions

Rain has impacted the snowpack overnight into Friday. Saturation of the upper layers has occurred, reducing surface structure. The deeper supportive snowpack is currently consolidated, with buried crusts contributing to structural integrity. The existing surface crusts in the southwest are robust and will take time to break down. The threshold is now about 1800 metres in the northwestern areas. Snow cover will exist on Mt Ngauruhoe and Mt Tongariro. Snow and ice are present on the Tongariro Alpine Crossing, but the current rain will be reducing snow cover. Alpine skills and equipment are essential to hike this track. Recommend alpine gear and take avalanche precautions. The threshold in the southwestern areas is at an elevation of about 1700 metres.

Mountain Weather

Saturday the 29th of August will have periods of heavy rain with snow to 2000 metres before dawn, easing in the evening. The winds are strong northerlies, easing throughout the day. The freezing level is at about 2300 metres. Several fronts move northeast over the South Island and central New Zealand today and tomorrow. Meanwhile, a low approaches the country from the north and affects the upper North Island tomorrow.

Sliding Danger

An overnight refreeze of the surface snow will result in slick and icy conditions. Numerous hazards, including exposed rocks and cliff bands, exist. It is recommended to carry an ice axe and crampons when venturing into the backcountry. Having strong alpine skills is essential for navigating over slick surfaces, as the consequences can be severe.

Forecast Confidence

Low

  • We are uncertain about forecast rain amounts.
  • We are uncertain about forecast snowfall amounts.
  • We are uncertain if precipitation will fall as rain or snow.

New Zealand Avalanche Advisory (NZ Mountain Safety Council)

Regions covered