Aoraki/Mt Cook

There are hard crusts below 2000m. South facing terrain will not soften, and cloud and cooling forecast Saturday may limit softening on other aspects.

A widespread cycle of wet loose and slab avalanching up to size 3 has been observed after the heavy snow and rain over night on the 12th. Slab avalanching was mainly around south and east aspects and limited to the storm snow. There was an outlier observation of a much deeper slab on steep unsupported ground high on Mt Darwin NW aspect at 2700m.

Overnight Wednesday up to 60cm of fell above around 2000m on the Divide. Up to 30cm has fallen above 2000m in eastern terrain. 30 -50mm of Rain below this elevation (2000m) soaked the snowpack. This has now frozen forming a strong, slick crust. Afternoon solar input may soften this though much colder weather is forecast with a freezing level lowering to 800m by Saturday evening. Snowpack tests performed on the 14th through the liebig and malte brun range would indicate that storm snow above 2000m has bonded reasonably well.

The mid and lower snowpack is generally strong and faceting observed recently in shallow areas will gaining strength with moisture and warmer temperatures.

Forecast

A fine start, then a few showers from late afternoon, falling as snow above 500 metres.

Wind at 1000 metres

Light, southeasterly 40 km/h developing in the afternoon.

Wind at 2000 metres

Light, southeasterly 30 km/h developing in the afternoon, rising to 50 km/h in the evening.

Wind at 3000 metres

Light, southeasterly 30 km/h developing in the afternoon.

Freezing level

1800 metres, lowering to 1500 metres in the south late morning, then lowering to 1200 metres everywhere in the afternoon, then lowering to 800 metres in the evening.

Issued: 1:37pm Fri 14 Aug

Crampons and ice axe are essential at the moment for alpine travel. There is a real slide risk below 2000m.

High

• The snowpack structure is well understood.