Stormy and unsettled weather continues for the next 2 days, although the bulk of the storm has passed.
The avalanche danger will remain HIGH on Friday as the snowpack needs to drain and settle. There is still the possibility of natural avalanches, which could be large and run below the snowline. Avoid avalanche terrain until the stormy weather has passed.
Wind slab has been developing since Saturday on a multitude of aspects. Strong winds and snow are forecast to continue, but now more from the east, than the west. Wind slabs could now be a couple of metres deep. Natural avalanches are possible on Friday.
Rain on the snowpack and on new snow can bring on loose wet avalanching, especially as the freezing level fluctuates during the storm. The freezing level is forecast to drop, which will improve the stability.
A lot of rain has fallen up to about 18/1900m. Rain at these lower and mid elevations has created a wet slab hazard. The snowpack will take some time to drain, and for stability to improve
No recent observations due to stormy condtions.
Sunday - 23rd. A size 3 natural avalanche off Mt Talbot, to valley floor. Suspect it to be wind slab
The biggest storm of the winter has just passed over, with gale winds, heavy rain and snow and a fluctuating freezing level. Any weak layers in the snowpack at high elevations will be tested. The snowpack is likely getting rain soaked below 18/1900m. There is little information available from the recent storm, yet.
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.
General snowpack description
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.
Periods of rain, some heavy, easing to showers in the morning. Rain returning at night. Snow lowering to 1000 metres at night.
Wind at 1000 metres - Gale northerly 70 km/h, changing westerly 40 km/h in the morning, rising to gale 65 km/h late evening.
Wind at 2000 metres - Gale northerly 80 km/h, changing westerly gale 70 km/h in the morning, easing to 40 km/h for a time in the afternoon.
Freezing level - 2000 metres, lowering to 1600 metres before dawn, then to 1300 metres in the afternoon.
Expect variable surface conditions. Take an axe and crampons if you're exploring when this storm clears.
Moderate
New Zealand Avalanche Advisory (NZ Mountain Safety Council)
