Avalanche forecast

Arthur's Pass

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

A rapid warming trend on Wednesday will increase the risk of loose wet avalanches on solar aspects. Beware of what is above you.

Shifting winds have created windslabs in unexpected places. Be wary of stiffer or hollow sounding snow pillows.

Route selection should allow for changing hazard during the day.

Avalanche problems

  • Loose Wet

    • All elevations
    Likelihood
    Likely
    Size
    1.5

    Loose wet hazard will increase during the day on Wednesday.

  • Wind Slabs

    • All elevations
    Likelihood
    Possible
    Size
    1.5

    Windslabs have formed on slopes all the way from NW through SE aspects. Take care on "filled in" pockets of otherwise wind scoured slopes.Be alert to firm snow pillows lee to ridge tops and around mid-slope terrain features.

Recent Avalanche Activity

No avalanche activity reported on 4 August but significant wind transport across ridge lines observed.

If you see anything, please report it in the public observations section of the NZAA website.

Current Snowpack Conditions

At higher elevations loose surface snow on S-SW aspects from the 31st July storm will have been redistributed over the past 12-24hrs. Winds shifting all the way through north west to southerly quarters will have produced a complex layering in the near surface snowpack. Expect wind stripped surfaces at higher elevations on windward aspects, with some deep pockets in the lees. On Tuesday, temps stayed cold and windslab will have developed on slopes lee to the S-SW, mainly above 1500m. Below this is a formerly wind pressed snowpack with no significant layers of concern. There are limited observations of the new snow line around the forecast area, but threshold for avalanches is estimated at around 1500m in the west, tapering east. At lower elevations (below 2000m) ice crusts exist but bonding to the ice layers has been good.

Mountain Weather

Forecast for Wednesday

Fine.

Wind at 1000 metres

Southwesterlies 35 km/h.

Wind at 2000 metres

Southerlies gale 75 km/h, easing to 45 km/h in the evening.

Freezing level

500 metres, lifting to 1200 metres by midday.

Sliding Danger

Expect areas to be stripped back to hard surfaces from the gale winds at higher elevations. Crampons and an ice axe are a good idea, as many firmer areas now exist.

Forecast Confidence

Moderate

  • We are uncertain due to a limited number of field observations.
  • We are uncertain due to the variability of wind effect on the snowpack.

New Zealand Avalanche Advisory (NZ Mountain Safety Council)

Regions covered