Tongariro

Wind slabs may increase in size as new snow gets transported to east and south aspects. The weather remains unsettled over the next 24 hours, with snow showers and strong winds expected. Poor visibility will make it difficult to identify hazards in the alpine backcountry. Recommend delaying backcountry travel until the conditions improve.

Multiple size 1 natural avalanches have been observed at Whakapapa’s Headwall. These were loose wet events at about 2300 metres.

New snow accumulation is difficult to assess due to wind effects. At 2300 metres (Turoa), 50 cm of wind drift was observed. This can be estimated as 20 to 25 cm of new snow over this past storm cycle. Wet and consolidated mass, which is displaying good bonding to the old snow surface. Rain has continued to impact the snowpack at the lower elevations. Over the past 24 hours, another 5 to 6 mm of rain has been recorded. Saturation of the upper layers has continued, with snowpack erosion and depletion occurring at the lower elevations (below 2000 metres). This is influencing surface structure, with stability being reduced. The deeper supportive snowpack is currently consolidated, with buried crusts contributing to structural integrity. The existing surface crusts in the southwest are robust but are starting to break down with rain saturation. The threshold is rising and is now about 1900 metres in the northwestern areas. Isolated slopes are still at threshold in the southwestern areas at about 1700 metres.

Monday the 31st of August will have a few showers, becoming widespread and heavier in the morning, with snow to 1400 metres from the afternoon. The winds are strong to moderate westerly. The freezing level is 2000 metres, lowering to 1700 metres before dawn, then lowering to 1300 metres in the evening. A low to the northeast of the upper North Island moves away to the east of the country today, while a strong, cold and unsettled southwest flow covers New Zealand today and tomorrow.

The snowpack has been saturated by recent rain at the lower elevations. With increasing winds and lowering freezing levels, there is a good chance a slick, icy surface crust will develop. Numerous hazards, including exposed rocks and cliff bands, exist. It is recommended to carry an ice axe and crampons when venturing into the backcountry. Having strong alpine skills is essential for navigating over slick surfaces, as the consequences can be severe.

Low

• We are uncertain about forecast precipitation amounts.
• We are uncertain if precipitation will fall as rain or snow.