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 and cornice exist on northern and western aspects. A loose wet avalanche problem may develop as winds ease and the sun returns. Recommend a conservative mindset with careful snowpack assessment as you travel. The weather is improving over the next 24 hours as high pressure starts to affect the region, bringing easing winds and fine conditions.

Avalanche problems

  • Wind Slabs

    • All elevations
    Likelihood
    Possible
    Size
    2

    Wind slabs have formed by strong to gale winds transporting the new loose snow. Light snow showers are possible overnight. Any subsequent snowfall accumulation will be deposited on west- and north-facing slopes, compounding this problem. Wind slab deposits may continue to form near sheltering terrain features and catchment. Triggering these wind slabs is more probable on steep slopes lacking support. Slopes such as the northern aspect of Tahurangi will have had continued loading over the past few days. It's advisable to approach any freshly loaded slope with caution, especially those that are convex-shaped and positioned high in the path.

  • Cornices

    • All elevations
    Likelihood
    Possible
    Size
    1.5

    Cornice formations exist near ridgelines facing north or west. New snow has been transported by the persistent southerly winds during the recent storm system. Cornices have an isolated distribution but can be reactive to light loads. Failure will be possible once weight exceeds support, triggering wind slab on the slope below. Recommend avoidance and maintaining a decent distance even after a storm event.

  • Loose Wet

    • All elevations
    Likelihood
    Possible
    Size
    1.5

    Loose wet avalanche activity will increase as cooling winds ease and the sun makes an appearance. Cold wind-driven new snow deposits will react negatively to any rapid warming. Solar aspects, mostly north-facing, will be prone to structural breakdown of surface layers. Watch for signs of solar effect such as rollerball and pinwheel activity.

Recent Avalanche Activity

Multiple avalanches up to size 1 were initiated by Whakapapa and Turoa ski patrols during slope assessment today, 19082026. Locations were at elevations up to 2300 metres on north- and west-facing aspects. Most were wind slabs, but some cornices were also triggered.

Current Snowpack Conditions

During this last storm cycle, Turoa has received about 30-40 cm of new snow above 1600 metres. This new snow was paired with gale southerly or southeast winds. Wind slab deposits are over 100 cm deep in the southern areas on northern- and west-facing aspects. Deposits have been reactive to heavy loads during testing today, 19082026. These wind slabs are hard, with loading patterns varying from upper to mid path. Typically, new-snow weaknesses form within these deposits during development, with the new-old snow interface serving as a potential bed surface. In the northwest, isolated pockets of wind slab exist. New snow has also accumulated in the northwest; snow transport has occurred, with wind-driven deposits forming also. The gale southerly winds continue to strip exposed slopes, leaving a rain crust at the surface. Threshold is now about 1800 metres in the northwestern areas. Snow cover will exist on Mt Ngauruhoe and Mt Tongariro. Sub-zero temperatures currently; snow and ice are present on the Tongariro Alpine Crossing. Alpine skills and equipment are essential to hike this track. If doing the Tongariro Crossing, you will be traveling over snow and ice with exposure to start zones at threshold. Recommend alpine gear and take avalanche precautions. Threshold in the southwest remains at an elevation of about 1600 metres.

Mountain Weather

Thursday the 20th of August will be partly cloudy with isolated morning showers. The winds are moderate southerlies, easing throughout the day Thursday and becoming light. The freezing level is about 1300 metres, lifting to 2200 metres in the morning. A showery south to southwest flow weakens today as a ridge of high pressure slowly pushes onto Aotearoa New Zealand from the west. The high remains over the country tomorrow.

Sliding Danger

Strong winds can strip exposed slopes, making the surfaces slick and icy. 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 and competence is essential for navigating over slick surfaces, as the consequences can be severe.

Forecast Confidence

Moderate

  • We are confident due to a stable weather pattern.
  • We are uncertain due to rapidly changing freezing levels.

New Zealand Avalanche Advisory (NZ Mountain Safety Council)

Regions covered