Severe Gale North West winds combined with frozen rain crusts have created a significant widespread sliding hazard on many aspects.
Forecast new snow with continuing Gale Westerly winds will form further windslab on East Aspects.
Whilst the avalanche hazard is easing the potential for long sliding falls is increasing
Fresh windslab will be forming on Eastern aspects. This will be sitting over older windslab that is likely to have been healing. Where windslab can be found the snow structure below is probably complex. A small avalanche may step down into older layers. Avoid areas of stiff wind slab, steep entries from ridgelines, convex rolls or cross loaded features
29th August - No avalanches reported or observed. Severe Gale North Westerlies affecting the Park.
28th August. As the storm has cleared we have gained observations on multiple large Loose Wet and Wet slab activity that has run to valley floor on a range of aspectsWet Slab activity to size 3 was also reported from Plateau Hut. Clearing skies also allowed for observations from Plateau hut of multiple Loose Wet avalanches to size 2.5 on the Malte Brun range 27th August - Haszard range - some observations of Loose wet avalanching during the afternoon on various aspects at 2000m and below. A brief break in the weather allowed for observations of Wet slab avalanches on East Aspects around 1100m. Poor visibility hindered any other observations
26th August - Large Loose wet avalanche reported running to valley floor on Mt Ollivier Fan below Mueller Ridgeline reaching the lower bush line. Further observations restricted by current storm cycle.
Gale and Severe Gale North Westerlies have been affecting the park on the 29th of August. There has been intense snow transport - however it is likely that this has also been accompanied by a great deal of sublimation. As a result expect that many aspects have been stripped back to previous hard Melt Freeze or Rain Crusts. Stiff wind slab is likely to have formed on South and East aspects above 2000m on very specific terrain features. Elsewhere firm sliding surfaces are likely to be found. Below 2000m a stout Rain crust will have formed on most aspects.
The recent winds have meant that we have again few direct observations of the snowpack
Showers. Snow lowering to 1000 metres in the afternoon.
Wind at 1000 metres
Westerly gale 70 km/h.
Wind at 2000 metres
Westerly severe gale 90 km/h.
Wind at 3000 metres
Westerly severe gale 90 km/h, rising to severe gale 110 km/h in the morning.
Freezing level
1600 metres, lowering to 1300 metres in the afternoon.
There is a significant sliding hazard at present on most aspects below 2000m and on windward aspects above 2000m. Ice axe and crampons are essential.
Low
New Zealand Avalanche Advisory (NZ Mountain Safety Council)
