Avalanche forecast

Tongariro

New Zealand Avalanche Advisory
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Avalanche danger

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

Wind slab formation at higher elevations is possible. New snow will start to be moved around by strong to gale northerlies. Loose wet avalanche activity remains a possibility at lower elevations. The weather is deteriorating over the next 24 hours with showers and poor visibility. Navigation and identifying hazards will be challenging when visibility is limited.

Avalanche problems

  • Wind Slabs

    • All elevations
    Likelihood
    Possible
    Size
    1.5

    Wind slabs may form at the higher elevations. Increasing northerly winds over the next 24 hours will transport new snow. Any loose material will be transported to south-facing aspects above 2300 metres elevation. This hazard is predicted to be stubborn to light loads and isolated to steep terrain features acting as catchments. Anticipated wind slabs will be small and low volume. Forecasted snowfall is light, minimising available snow for transport.

  • Loose Wet

    • All elevations
    Likelihood
    Possible
    Size
    1.5

    A loose, wet avalanche problem may develop on any steep unsupported slopes. Rain is likely at the lower elevations. 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 avalanche activity has been reported or observed over the past 24 hours.

Current Snowpack Conditions

Rain has impacted the snowpack over the past 36 hours. Not enough rain to reduce snowpack stability to a significant degree. A melt-freeze cycle has been occurring with refreezing overnight and a release during the day. Above 1900 metres, surface crust was very slick and icy first thing this morning (check photo). This crust will be resistant to any subsequent bonding if loaded by new snow despite irregular surface. The deeper supportive snowpack is currently consolidated with no significant weaknesses identified but is heading isothermal at the lower elevations. 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. 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. The threshold in the southwestern areas is at an elevation of about 1700 metres.

Mountain Weather

Friday the 28th will be cloudy with a few showers. Turning to rain at night, possibly heavy, with snow to 1800 metres. The winds are from the north, moderate but increasing overnight, becoming gale force. The freezing level is about 2300 metres elevation. A trough over the South Island deepens today, while a ridge over the North Island moves east. The broad trough moves onto the North Island tomorrow, while an associated low moves southeast across the lower South Island.

Sliding Danger

Surface refreezing overnight has been occurring, resulting in a slick, icy crust. This will increase the chance of a sliding accident. 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 is essential for navigating over slick surfaces, as the consequences can be severe.

Forecast Confidence

Moderate

  • The snowpack structure is well understood.
  • We are uncertain due to rapidly changing freezing levels.

New Zealand Avalanche Advisory (NZ Mountain Safety Council)

Regions covered