The New Zealand Avalanche Advisory (NZAA), which is operated by MSC, identified a range of avalanche problems for the weekend, including persistent slabs, with most regions given a “moderate” or “considerable” avalanche danger rating.
Persistent slabs are characterised by difficult-to-detect layers buried deep within a snowpack. The slabs often behave unpredictably, including being triggered from a distance.
“To safely navigate this terrain, backcountry enthusiasts need to get the NZAA avalanche forecast and adapt their plans based on the information. They must have proper training to mitigate their risk and carry avalanche rescue equipment and know how to use it.”
The NZAA provides daily avalanche forecasts for 13 backcountry alpine regions around Aotearoa.
On Sunday, the Tūroa ski patrol on Mt Ruapehu reported signs of an avalanche outside the ski area.
This prompted a search operation as it was unclear if anyone was in the area at the time. The debris was searched using avalanche transceivers, followed by a Recco detector and then the local search and rescue dogs avalanche team. After a comprehensive search, no one was found.
It followed two incidents in the South Island on Saturday.
In Canterbury’s Craigieburn Range, a skier in a party of three triggered a persistent slab avalanche. One skier was caught in its path but managed to escape without injury. The incident occurred not far outside the Porters ski area and was reported to the patrol team about 40 minutes after the event.
A snowboarder in a party of three triggered a persistent slab avalanche outside the Fox Peak ski area in the Mackenzie region. The result was a 250-metre-long, 50-metre-wide avalanche. No one was caught in its path.
“Skiing within the ski field boundary means you’re within a controlled environment where ski patrols monitor and manage avalanche danger,” Daisley said.
“In contrast, skiing in the backcountry is an uncontrolled, wild environment, where avalanche hazards are not actively managed.
“Those venturing beyond the patrolled ski area boundaries need to take responsibility for assessing the terrain, understanding snow conditions and making safe decisions.”
