Avalanche forecast

Two Thumbs

New Zealand Avalanche Advisory
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Avalanche danger

High Alpine · above 1,800 m
2 · Moderate
Alpine · 1,200 m–1,800 m
2 · Moderate
Sub Alpine · below 1,200 m
1 · Low
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Highlights

New snow will build windslabs at higher elevations.

If more than the forecast 10cm of snow arrives, the danger could reach CONSIDERABLE.

Be prepared for a widespread sliding hazard with lots of rocks in the runouts.

Avalanche problems

  • Wind Slabs

    • All elevations
    Likelihood
    Likely
    Size
    1

    Windslabs are likely to build above about 1700m over Thursday night and into Friday. They could be easily triggered due to poor bonding with previous weak snow surfaces or hard smooth crusts.

    Only 10cm of snow is forecast for the region. This could build slabs up to 50cm thick around ridges and terrain features that face south, southeast or east.

    If more than 20cm or snow actually arrives, the slabs will be larger, more dangerous and could be easier to trigger. The danger will be Considerable.

    Visibility will likely be poor, so it will be hard to identify windloaded areas and manage the terrain.

    Even a small avalanche may be consequential with rocks or cliffs in the runout.

  • Loose Wet

    • All elevations
    Likelihood
    Possible
    Size
    1

    At lower elevations we expect around 10mm of rain.

    This could cause loose wet avalanches on steep terrain.

Recent Avalanche Activity

No recent avalanches have been reported.

If you see any activity on the Two Thumb Range, please make a public observation. It really helps us to produce accurate forecasts.

Current Snowpack Conditions

Expect around 10cm of new snow on Thursday night to be distributed by gale NW winds.

Previous gale force wind from the northwest and southwest has left old crusts and rock exposed on ridges and upper elevations.

Deeper snow has been reported at mid and lower elevations on northern slopes.

A widespread rain crust below about 2200m has undergone several melt freeze cycles on sunny slopes

Snow depths in the south are about 70cm, tapering to about about 50cm mid range and 40cm in the north.

The snowpack north of Stag Saddle is not well understood, with no direct observations. It is possible that above about 2300m very deep snow has accumulated.

Mountain Weather

Scattered showers with snow possible to 1000 metres.

Wind at 1000 metres

Northwesterly 60 km/h easing to 30 km/h in the afternoon. Turning southwesterly 45 km/h at night.

Wind at 2000 metres

Northwesterly severe gale 95 km/h easing to 60 km/h in the morning. Turning to southwesterly 60 km/h at night.

Freezing level

1900 metres, lowering to 1300 metres in the evening.

Sliding Danger

The wind has stripped the soft snow back to exposed crusts.

Below 2000m, the snowpack has gone through melt freeze cycles, so any overnight freeze will form a slick crust.

Expect high sliding danger with lots of rocks in the runouts.

Iceaxe and crampons are highly recommended.

Forecast Confidence

Moderate

  • We have a good understanding of the snowpack structure and confidence in the weather forecast.
  • We are uncertain about forecast precipitation amounts.

New Zealand Avalanche Advisory (NZ Mountain Safety Council)

Regions covered