Surface conditions remain the primary concern. Extensive areas of rime exist above 1600 metres elevation, mostly on south-facing slopes. A loose wet avalanche problem may develop on the solar aspects. Clear conditions at times with light to moderate southeast winds over the next 24 hours, but showers remain a possibility. With the freezing level lowering and cooling southeast winds, a refreeze is likely.
Loose wet avalanche activity cannot be ruled out. High-angle sun-affected slopes during the warmest period of the day will be the locations of concern. Intermittent light rain showers may also weaken the surface structure. Lowering freezing levels and moderate cooling winds may counteract the structural breakdown of the surface snow. Be alert to signs such as increased foot and ski penetration, roller ball activity.
No human or naturally triggered avalanches have been reported or observed over the past 24 hours.
The main characteristic of the current snowpack is the presence of impenetrable rime formations. These surface deposits are dangerous and unforgiving, particularly on the south and west-facing slopes. The rime formations are resistant to saturation by rain and even to solar effects, and they may take considerable time to break down. Yesterday, the 18th of July, a comprehensive snowpack observation was passed on. These observations were at 1550 metres elevation on a northeast aspect. This is a snapshot of one location showing a consolidated moist snowpack with a density inversion. The current snowline is approximately 1600 metres. The estimated threshold of snow cover that buries bed surface irregularities is slightly higher at around 1700 meters. Above 1700 metres, avalanches will run freely. Recent rain has lifted the snow line and eroded the snowpack.
The 20th of July will be partly cloudy, with isolated showers in the afternoon and evening. The winds are moderate to light southeasterly over the next 24 hours. The freezing level is at 2300 metres, lowering to 1900 metres over the next 24 hours. A complex trough moves slowly northwards over the country today and tomorrow, while a ridge builds over the country, south of the trough.
Rime crust on southern slopes is slick, hard, and dangerous. These conditions require a high level of skill and competence. The consequences of a fall and slide can be severe, as there are many hazards, such as exposed rocks and cliff bands. It is essential to carry the appropriate gear, including crampons and an ice axe. Mount Taranaki is highly exposed to weather patterns coming from multiple directions, which significantly affects the snowpack and surface conditions in a unique and volatile manner. Rime and rain events are frequent, and the rime ice can be robust and impenetrable; even experienced climbers may struggle with these conditions.
Moderate
New Zealand Avalanche Advisory (NZ Mountain Safety Council)
