Tongariro

Wind slabs are lingering on north and west aspects. Exposed slopes have been stripped of loose snow, leaving a hard icy crust. Sliding hazard exists. Recommend a cautious approach when travelling over slick surfaces, as the consequences can be high. The weather is settled over the next 24 hours. A ridge of high pressure affects the region, bringing light winds and clear conditions.

No avalanche activity has been reported or observed over the past 24 hours. Targeted slope testing at Turoa this morning resulted in no avalanches being triggered. This has increased confidence in the snowpack stability.

No precipitation has affected the snowpack over the past 24 hours. A hard slab with a density inversion formed during the last storm event. These deposits have a drum-like feel when travelling over and mostly in the southern areas of the region. The gale winds have also stripped and sublimated the new snow from ridgelines, exposing the rime crust. In the northwestern areas near Whakapapa, a facet crust combination weakness has been noted. Snow cover exists on Mt Ngauruhoe and Mt Tongariro, with new snow transportation observed today. These northern mountains are likely to have wind slabs also. If doing the Tongariro Crossing, you will be traveling over snow and ice with start zones at threshold. Recommend alpine gear with avalanche precautions. The south-west areas have enough snow cover in start zones above 1500 metres for avalanches to run freely (threshold). In the northern areas, the threshold is at a slightly higher elevation, but this is also changing fast. Recent snowfalls have improved snow cover overall and lowered the threshold elevation in the northern and eastern areas (about 1600 metres elevation).

Tomorrow, Friday the 7th of August, will have a fine morning, but clouds will increase from the afternoon. The winds will be a light southerly tending westerly later in the day. The freezing level will be about 1200 metres elevation, lifting to 1600 metres in the morning. A ridge of high pressure lies over New Zealand today. The ridge remains slow-moving over the North Island tomorrow, while a front moves onto the western South Island.

Crusts exist, and at some locations is very slick and icy. Winds have stripped ridgelines and windward terrain features, exposing hard icy crusts. Numerous hazards, such as exposed rocks and cliff bands, remain. Carrying an ice axe and crampons is recommended in the backcountry. It is essential to have strong alpine skills and competence when travelling over slick surfaces with high consequences.

High

• We have a good understanding of the snowpack structure and confidence in the weather forecast.