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

Small pockets of wind slab may build near ridge-top and in cross-loaded gullies. With shifting winds, these will be on any aspect at upper elevations.

Firm snow, ice and exposed rocks present a significant hazard in many areas.

Use careful route selection around ridge-lines, gullies and above rocky runouts.

Avalanche problems

  • Wind Slabs

    • All elevations
    Likelihood
    Unlikely
    Size
    1

    With winds switching from north-west to north-east, then south-east during the day, small pockets of wind slab may build on any aspect at upper elevations. You will find these in sheltered lee terrain, particularly near ridge-lines, below roll-overs and in cross-loaded gullies.

    Wind slabs are more likely to be found in areas where enough soft snow remains for transport. If the forecast snow arrives earlier in the day, or more than 10cm falls, you can expect the hazard to rise to MODERATE.

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

  • Loose Wet

    • All elevations
    Likelihood
    Unlikely
    Size
    1

    If it starts to rain, the likelihood of small loose wet avalanches will increase.

    Look for roller-balling and signs the snow is losing cohesion.

    Be ready to adjust your route if necessary.

Recent Avalanche Activity

No new avalanche observations over the past 2 days.

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. Firm crusts and areas of wind-affected snow are widespread, with the most variable conditions found in the high alpine.

Sheltered terrain continues to hold soft snow — up to 20cm of cold wind-drifted snow can be found in sheltered bowls that have escaped the southwest gales.

Snow depth varies from 40-70cm, with deeper accumulations of 100-120cm in sheltered areas.

Small facets (weak sugary crystals) have begun developing around crusts in the upper snowpack, particularly on shallow shaded slopes. At present, these are not posing a significant problem. Below the crusts, the lower snowpack is well settled.

Northern end of range — north of Stag Saddle

The snowpack north of Stag Saddle is not well understood, with no direct observations. We expect that deep snow will have accumulated in sheltered areas above 1800m.

Mountain Weather

Partly cloudy with morning frosts and isolated showers. Rain developing in the afternoon, with snow to 1500 metres.

WIND AT 1000 METRES

Northwesterly 30 km/h, but 50 km/h in exposed places, dying out in the morning. Northeasterly 50 km/h developing late evening.

WIND AT 2000 METRES

Northwesterly 45 km/h, dying out in the morning. Northeasterly 60 km/h, but southeasterly 40 km/h about the Mackenzie Basin developing in the evening.

FREEZING LEVEL

2000 metres, lowering to 1500 metres about the Mackenzie Basin in the evening.

Sliding Danger

Firm snow surfaces, exposed ice and rocks are widespread and will present a greater hazard than avalanches in areas previously exposed to the south-west gales. A slip or fall on steep terrain could have serious consequences, particularly above bluffs, in gullies or where runouts are confined.

Take extra care when travelling on hard snow, 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 are uncertain about forecast precipitation amounts.
  • We are uncertain if precipitation will fall as rain or snow.
  • We are uncertain whether the wind will be enough to form new wind slabs.

New Zealand Avalanche Advisory (NZ Mountain Safety Council)

Regions covered