Avalanche forecast

Two Thumbs

New Zealand Avalanche Advisory
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Avalanche danger

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

Rising temps could cause loose snow avalanches on sunny slopes.

Pay attention to signs that the snow pack is heating up and be prepared to change your plans.

Avalanche problems

  • Loose Wet

    • All elevations
    Likelihood
    Possible
    Size
    1.5

    Warmer temperatures and sun on Sunday will mean at lower elevations things will warm up. Loose snow activity is possible in the heat of the day on steep, sunny slopes. There's a lot of snow on the northern half, so these could get quite large given a big enough slope that rapidly warms.

    Timing is everything. Anticipate where the sun will be baking the snowpack. Watch for signs of rollerballing. Consider what is above you and where you would end up if caught.

    Be prepared to change you plans if you see signs of significant warming.

  • Wind Slabs

    • All elevations
    Likelihood
    Unlikely
    Size
    1

    With the wind expected to turn north-west and pick up in the afternoon, small windslabs may start to form on south, south east and east facing terrain.

    Managing the risk of small avalanches is often about looking at the consequences. Before committing to a particular slope, consider where you will end up if a small slide knocks you off your feet. South facing terrain has a shallower snowpack right now. It is more likely to hide rocks that could cause injury in a slide.

Current Snowpack Conditions

The storm snow from last week has settled. Snow depths in the south are about 70cm, tapering to about about 50cm mid range and 40cm in the north.

The snow has been distributed by gale southerly winds with deep drifts on northerly facing terrain and exposed ridges are scoured. Testing on windloaded slopes in the south of the range shows good bonding.

At the southern end of the range, a thick, but breakable rime crust makes off piste skiing very challenging, particularly on south facing terrain. This weakens as you head north. It was not observed around Round Hill Ski Area or around Camp Stream. Elsewhere, north facing terrain has developed sun crusts, while south facing holds dry snow, but is much thinner.

The snowpack north of Stag Saddle is not well understood, with no direct observations.

Mountain Weather

Fine, apart from areas of low cloud and valley fog. Severe morning frosts.

Wind at 1000 metres

Westerly 30 km/h developing in the morning, rising to northwesterly 60 km/h on the eastern slopes in the evening.

Wind at 2000 metres

Westerly 30 km/h, rising to northwesterly 60 km/h in the evening.

Freezing level

1700 metres.

Sliding Danger

Sliding danger is low due to new snow.

Forecast Confidence

Moderate

  • We are confident due to a stable weather pattern.
  • We are uncertain due to a limited number of field observations.

Recent Avalanche Activity

A small loose wet avalanches were reported in steep terrain in the Camp Stream area on Saturday. 1800m NW facing slope.

5 slab avalanches were triggered naturally, possibly by cornice fall near the end of the storm on Wednesday. They were up to size 2 (large enough to bury a person) on a NW aspect at 2100m on the Richmond Range.

Two loose dry avalanches ran naturally, on Mt Maude, probably during the storm. They were size 2 on a N aspect. They ran right to ground.

There have been limited observations of terrain post storm, so other avalanches are possible.

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

New Zealand Avalanche Advisory (NZ Mountain Safety Council)

Regions covered