A storm from the North, with very strong wind, is forecast to pass over Fiordland on Wednesday. New snow at higher elevations and rain at mid elevations will create both wind slab and loose wet avalanche activity.
Take a conservative approach to any backcountry travel. Conditions and visibility are likely to deteriorate as the avalanche danger is rising.
New reactive wind slab is expected to develop with the forecast snow and increasingly strong winds from the North. This is most likely on the steep ground near the ridgetops or on steep mid-slope rolls.
Rain on snow is forecast today, at low and mid elevations. This will bring on some loose wet and possibly wet slab activity, especially during times of heavy rain. The freezing level is forecast to rise over the next 24 hours, resulting in rain on new snow, and a series of loose wet activity out of steep terrain.
Surface conditions are variable, with wind scouring on windward slopes. Take an axe and crampons if you're exploring.
Moderate
Tuesday 12 Aug - Loose wet activity observed on all sunny aspects throughout the Darran Mountains
Sun 9th Aug- Some wet loose activity reported during rain in the Gertrude Valley area.
Fri 7th to Sun 9th. Up to 25cm fell in above about 1700m in northern Fiordland. Expect some slab development in the steep ground near ridgetops. Below about 1700m expect a lattice of rain crusts or even rain-soaked snow at the very low elevations.
Above 1800 this snow overlies a snowpack that is thought to be stable. It is expected to have layers but has been tested by strong wind loading and wind stripping from both the west and the SE in early August.Below 1800 new snow overlies a thin snowpack has had rain on it at the beginning of pretty much all the winter storms, and is thought to be well stable.
Periods of heavy rain developing in the morning, with snow to 1500 metres.
Wind at 1000 metres - Northerly gale 65 km/h but severe gale 95 km/h about the fiords. Rising to northerly severe gale 120 km/h in the morning, easing to gale 85 km/h in the afternoon and then to gale 65 km/h in the evening.
Wind at 2000 metres - Northerly severe gale 90 km/h, rising to severe gale 120 km/h for a time in the morning and afternoon.
Freezing level - 1800 metres.
New Zealand Avalanche Advisory (NZ Mountain Safety Council)
