New Zealand · New Zealand Avalanche Advisory · partie de New Zealand
Danger d’avalanche
Bulletin émis 9 hours ago · valide jusqu’au Sep 1
Publié par New Zealand Avalanche Advisory
A series of fronts are lined up for Fiordland in the next week. New snow is in the forecast, down to about 1100m.
Wind slab will be forming, especially at higher elevations, which have had more snow.
Wind slab has been developing on a multitude of aspects. Strong winds and snow are forecast to continue, but now more from the west. Wind slabs could now be a couple of metres deep at the highest elevations. Below 2000m the wind slab will be forming on a refrozen rain crust.
The freezing level is forecast to drop, which will improve the stability. Loose wet sluffs may still be possible out of steep terrain, particularly if there is rain on new snow.
Expect variable surface conditions. Take an axe and crampons if you're exploring.
Moderate
27 August - A widespread natural wet slab cycle in Northern Fiordland as the FAFL rose and there was rain to 2000m. A couple of size 3s, and many size 2s observed.
Sunday - 23rd. A size 3 natural avalanche off Mt Talbot, to valley floor. Suspect it to be wind slab
30 August - Est about 30cm of new snow above 16/1700mm from the NW/W
29th August - Over 400mm of precip fell 22 - 28th August. During this, the FAFL fluctuated wildly and winds were gale, and from all directions. As a result of this the snowpack is rain soaked below about 2000m, and above this about 2-3 m of new wind affected snow. The snowpack at the highest elevations is expected to hold layers. Below approx 2000m the snowpack has had a reset and is draining and starting to refreeze.
Estimate about 70-100cm of snow above 1700m since 21st of August. This has been moved by gale to extreme winds (mainly from the NW), resulting in sublimation and stripped windward slopes and ridges. Any wind loading could be couple of metres deep and has been observed more mid slope. Below 1700m has been rain.
15 Aug - Below 2000/2200m. Any new snow has fallen on a thick rain crust (14 Aug), with a refrozen wet snowpack underneath. - Above 2000m/2200m. The snowpack is expected to be dry and layered, especially on southerly facing slopes of the highest peaks.
Showers, some heavy with hail, clearing north of Milford Sound in the evening. Snow lowering to 300 metres in the afternoon.
Wind at 1000 metres - Westerly severe gale 90 km/h, easing to southwesterly gale 70 km/h in the evening.
Wind at 2000 metres - Southwesterly severe gale 100 km/h, easing to gale 80 km/h in the evening.
Freezing level - 1000 metres, lowering to 600 metres in the afternoon.
New Zealand Avalanche Advisory (NZ Mountain Safety Council)
