Bollettino valanghe

Two Thumbs

New Zealand Avalanche Advisory
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Pericolo valanghe

High Alpine · above 1,800 m
2 · Moderato
Alpine · 1,200 m–1,800 m
1 · Debole
Sub Alpine · below 1,200 m
Senza grado
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Non aggiornato — questo bollettino è scaduto 3 weeks ago. Stai vedendo condizioni passate, non il bollettino in corso.

In sintesi

Expect small pockets of wind slab to build on the south-eastern half and in cross-loaded gullies.

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.

Problemi valanghivi

  • Wind Slabs

    • Tutte le quote
    Probabilità
    Possible
    Dimensione
    1

    Incoming north-west winds will build small pockets of wind slab in sheltered lee terrain (north-east, east, south-east and south facing slopes), particularly near ridge-lines, below roll-overs and in cross-loaded gullies.

    Wind slabs are likely to be small and isolated. They are more likely to be found in areas where enough soft snow remains for transport. Expect wind slabs to be larger north of Stag Saddle, and if incoming new snow is more than the 2-5 centimetres forecast.

    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

    • Tutte le quote
    Probabilità
    Possible
    Dimensione
    1

    With incoming rain and rising freezing levels, small loose wet avalanches are possible.

    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

Cloud increasing with patchy rain, more persistent about the Divide.

WIND AT 1000 METRES

Northwesterly 35 km/h, but 60 km/h in exposed places.

WIND AT 2000 METRES

Northwesterly 35 km/h, rising to gale 70 km/h in the morning, then easing to 45 km/h at night.

FREEZING LEVEL

1600 metres, lifting to 2000 metres 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 confident the likelihood of avalanches will increase with the forecast weather.
  • We are uncertain about forecast precipitation amounts.
  • We are uncertain if precipitation will fall as rain or snow.

New Zealand Avalanche Advisory (NZ Mountain Safety Council)

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