Bulletin d’avalanche

Arthur's Pass

New Zealand Avalanche Advisory
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Danger d’avalanche

High Alpine · above 1,800 m
3 · Marqué
Alpine · 1,200 m–1,800 m
3 · Marqué
Sub Alpine · below 1,200 m
Sans niveau
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Points saillants

A ferocious NW storm will bring high winds, rain and snow, raising the avalanche hazard once the storm hits.

Natural avalanches are likely during the storm and mountain travel is not recommended.

Timing the onset of the storm is difficult, so bunker down on Saturday and let nature do its thing.

Problèmes avalancheux

  • Loose Wet

    • Toutes altitudes
    Probabilité
    Likely
    Taille
    1.5

    Up to 100mm of rain is forecast with uncertain timing of when it will arrive and how intense it will be. Rain on snow may trigger a widespread loose wet avalanche cycle on all aspects.

    At lower elevations, beware of saturated snow sitting over a snowgrass sliding surface.

  • Wind Slabs

    • Toutes altitudes
    Probabilité
    Likely
    Taille
    2

    Significant snowfalls up to 1m at higher elevations will sharply increase the windslab hazard on slopes lee to the NW.

    While these slope are mostly in the south-easterly half, winds can 'wrap around' terrain features creating hazards in unexpected places. This weekend is a time for heightened vigilance.

    Beware of sudden changes in snow density, with stiffer or hard snow indicating the presence of windslab.

Recent Avalanche Activity

A small loose wet avalanche cycle played out this week ahead of the new storm.

Park user observations provide important information. Please help us.

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

Current Snowpack Conditions

The snowpack has received a week of heat from sun and mild temps and is gaining strength but variations exist by elevation. Above ~1600m it is mainly consolidated. Below that ,a melt freeze crust has capped weak isothermic snow. The threshold for avalanches ahead of the incoming storm is estimated at around 1500m in the west, tapering east.

Mountain Weather

Forecast for Saturday 22 August

Rain with snow to 1400 metres, and heavy falls from afternoon.

Wind at 1000 metres

Northwesterly 50 km/h, rising to gale 80 km/h in the morning.

Wind at 2000 metres

Severe northwesterly gale 90 km/h, rising to severe gale 115 km/h in the morning.

Freezing level

1600 metres, lifting to 2100 metres in the morning.

Sliding Danger

Elevated sliding danger currently exists throughout the Park ahead of the storm, but mountain travel should be limited this weekend. If you must travel ahead of the storm, ice axe and crampons are essential.

Forecast Confidence

Moderate

  • We are uncertain about forecast precipitation amounts.
  • We are uncertain due to rapidly changing freezing levels.
  • We are uncertain due to the timing of the incoming weather system.

New Zealand Avalanche Advisory (NZ Mountain Safety Council)

Régions couvertes