Tongariro

Avalanche problems

• 

  Wind slab

  Wind slabs are formed when loose snow in near-surface layers (new snow or old snow) is transported and deposited by wind.

  Avoid wind-drifted deposits in steep terrain.

  Affected aspects

  SouthwestWestNorthwestNorthNortheast
• 

  Wet snow

  The avalanche problem is related to a weakening of the snowpack due to the presence of liquid water. Water infiltrates the snowpack due to melt or rain.

  Good timing and trip planning are important. Consider avalanche runout zones.

  Affected aspects

  WestNorthwestNorthNortheastEast
• 

  Cornices

  A wave-like formation of soft or hard wind drifted snow, often overhanging.

  Avoid travel on and below large ridge-top cornices.

  Affected aspects

  SouthwestWestNorthwestNorthNortheast

Stability

An estimated 10 to 30 cm of new snow has accumulated in the southwestern areas of the region over the past 48 hours. Winds have transported this new snow to north and west aspects, forming wind slab deposits up to 90 cm in depth at higher elevations. Meanwhile, northern areas have been stripped of snow by strong downslope winds. Before the freezing levels dropped and snowfall began, the older snowpack was significantly affected by a large amount of rain. This rain-soaked snowpack has now refrozen, locking up. At lower elevations, the snowpack continues to erode, and snowlines are rising, which is typical for spring. Waterfall holes and free-flowing water beneath unsupportive snow in gullies pose an increasing hazard. These waterfall holes are particularly dangerous during spring and are mostly found in lower elevation gullies. Additionally, ice falls have been observed near Turoa, with reports of similar conditions elsewhere. This unpredictable and dangerous hazard is more likely to occur during the warmest part of the day or during rapid warming events. Glide cracks are also starting to appear, posing a hazard downhill of breakovers and often difficult to see if descending quickly. The threshold is about 2000 metres in the northwestern areas and about 1900 metres in the southwest.

Snow quality

No avalanche activity has been reported in the last 24 hours. Poor visibility and weather conditions have limited comprehensive observations.

Weather

Sunday the 18th of October will have some cloud to the south in the morning; otherwise fine. The winds are gale southerly but easing as the day progresses. The freezing level is 1700 metres, lifting to 2300 metres before dawn, then to 2900 metres in the evening. A slow-moving high over the Tasman Sea extends a ridge of high pressure across the country today and tomorrow.