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
1 · Low
Sub Alpine · below 1,200 m
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Highlights

A fine day with warm temperatures and spring conditions.

Check the overnight freeze to avoid slides and injuries. Un-tracked North-East slopes might yield the best corn snow.

Avalanche problems

  • Loose Wet

    • All elevations
    Likelihood
    Possible
    Size
    1

    Despite the warm air temperatures and rain, few to no loose wet avalanches have been reported in the Two Thumbs until the evening of 13 Aug. We assume the warm aspects have been mostly wind stripped and do not hold enough snow to avalanche.

    In the North a loose wet avalanche cycle should have run and shed most snow for natural loose wet avalanches.

    Tomorrow we expect very few natural loose wet slides, but skiers could trigger a small avalanche in steep sunny terrain once the surfaces have warmed up.

    In the South, it is unlikely to trigger a loose wet avalanche, but possible if a very shallow snowpack warms to ground and slides on tussock.

  • Wind Slabs

    • All elevations
    Likelihood
    Unlikely
    Size
    1

    The wind did not blow as much or as long as we had expected from forecasts. Only small wind slabs might have built and will heal quickly with the warm temperatures. We think that only in the far North of the range, in terrain above 2200m, small isolated pockets might still lurke.

    Look out for smooth, rounded pillows of wind-drifted snow, changes in snow texture and hollow-feeling slabs over firmer old snow. Think about terrain selection in steep alpine terrain, particularly where even a small avalanche could carry you into rocks, gullies or over cliffs.

Recent Avalanche Activity

We only received a maximum of 15-ish cm of new snow in the far North tapering to nothing in the South. No avalanche observations were reported from the Two Thumbs Range.

Guides at Lady Emily have reported a small loose wet avalanche cycle with size 1-2 avalanches, mostly on East to Northeast aspects from steep terrain at 2000m-2200m.

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

Current Snowpack Conditions

Southern end of range — south of Stag Saddle

Ridge-lines and slopes exposed to the south-west, have been heavily scoured, and mostly stripped back to old crusts, or even bare rocks and scree on upper ridges. All surfaces have softened and were moist to the tops.

Sheltered terrain above 1800m on the Eastern half still has a firm base, but surface snow is moist to high elevations. Only above approximately 2200m dry snow may have survived the warm weather. The crusts are mostly decomposed and the lower snowpack is well settled and consists of mainly meltforms or round crystals.

Snow depth varies from 40-50-cm, with deeper accumulations of 100-120cm in sheltered areas.

Northern end of range — north of Stag Saddle

The snowpack north of Stag Saddle is not well understood, with no direct observations. Judging from reports out of the Cass Valley, the snowpack would have been saturated to 1900-2000m. We expect the area would have seen a loose wet avalanche cycle similar to the observations in the Cass Valley. We expect that deep snow will have accumulated in sheltered areas above 1800m.

Mountain Weather

Areas of morning low cloud and frosts, otherwise fine.

WIND AT 1000m & 2000m: Light.

FREEZING LEVEL: 2000m.

Sliding Danger

The warm weather and the rain have softened all surfaces. However, larger parts of the range will experience a clear night and moist surfaces will re-freeze. A slip or fall on steep terrain could have serious consequences. Many run out areas are now bare rock or scree.

Take extra care when travelling on hard snow in the morning before the surfaces will soften again! Assess runout zones before committing to steep slopes, and carry equipment appropriate for firm alpine conditions, such as crampons and an ice axe. Conservative route selection remains the most effective way to manage these hazards.

Forecast Confidence

Moderate

  • We have a good understanding of the snowpack structure and confidence in the weather forecast.
  • We are uncertain due to a limited number of field observations.

New Zealand Avalanche Advisory (NZ Mountain Safety Council)

Regions covered