Higher elevation terrain has received a lot of snow that will need time to settle.
Lower down, rain has weakened the snowpack.
Careful evaluation of the snowpack and conservative terrain choices are recommended.
The south end of the range has received significantly less rain and snow, so the danger is lower there.
Gale northwesterlies will continue to build fresh windslabs onto slopes that face south, southeast and east.
This problem will be mainly found above about 2000m where there is more wind transportable snow.
Heavy rainfall up to about 2100m has weakened the snowpack. The main concern for wet slab avalanches is where significant rain fell on a previous snowpack that was cold and layered. This is mainly at higher elevations 1800-2100m and shady slopes below 1800m.
Significantly more rain has fallen north of about Round Hill, so the problem will be greater there.
It is recommended to avoid consequential steep slopes and runouts for another 24hours to allow the free water to drain. Even if the surface has refrozen.
The late August sun will carry some power. Loose wet avalanches are possible out of steep sunny terrain in the heat of the day.
Mainly fine, with passing high cloud.
Wind at 1000 metres
Northwesterly gale 65 km/h, rising to gale 85 km/h in exposed places in the evening.
Wind at 2000 metres
Westerly gale 70 km/h, rising to severe gale 90 km/h in exposed places in the evening.
Freezing level
1800 metres.
Clear skies overnight may cause the saturated snowpack to refreeze. If the crust is supportive, there will be widespread sliding danger.
There will be lots of rocks in the runouts.
Carrying skin crampons, iceaxe and boot crampons and careful evaluation to the conditions is recommended.
Low
Two large, size 3 avalanches were observed across the Godley Valley from Round Hill. They were likely either wetslabs triggered by rain or storm slabs triggered by heavy snow. Both are possible with the previous storm's freezing levels. They were on east facing terrain at about 2000m
It is likely that there are similar avalanches in the north area of the Two Thumb Rainge. Observations have been limited due to the storm.
If you see any activity on the Two Thumb Range, please make a public observation. It helps us to produce accurate forecasts.
The tops of the highest peaks in the area have received a lot of new snow -possibly up to 100cm. This has been distributed by Gale NW winds.
Rain has saturated the snowpack below about 2100m. A brief cold snap on Wednesday night delivered about 5-10cm of fresh snow to low levels before turning back to rain.
Prior to the storm the old snow pack was well settled with wind blown pockets sitting over surface crusts in most places.
Snow depth varies from 40-75cm, with deeper accumulations of 100-120cm in sheltered areas.
New Zealand Avalanche Advisory (NZ Mountain Safety Council)
