Small windslabs will continue to form around ridges and terrain features.
Take extra care to evaluate windloaded slopes before committing.
Windslabs are likely to be mostly small and confined to areas sheltered from the W wind around ridges and terrain features. It is possible that larger windslabs are present in isolated slopes. Pay particular attention to the consequences of a small avalanche knocking you off your feet.
Cold temperatures should keep the loose wet danger away on Monday. However, if it warms up more than expected, a loose wet cycle could happen on steep sunny slopes. Particularly where new snow sits on a solid crust. Keep an eye out for signs of the snow heating like rollerballing. Be prepared to change plans to avoid consequential sunny avalanche terrain if you notice it getting too warm.
A natural windslab was observed on Pk 2211, NE of Erebus. E aspect, Sz 1.5-2. likely ran during the storm on Friday or Saturday.
Multiple size 1 (Too small to bury a person) windslabs were deliberately released by ski cut on Saturday 24 July. They were on north east facing terrain below 2000m. These slabs failed on the previous snow surface prior to the storm which was a solid melt freeze crust.
If you see any activity on the Two Thumb Range, please make a public observation. It really helps us to produce accurate forecasts.
Over 20cm of new snow fell in the north above 2100m on Friday with 20mm of rain soaking the snowpack at lower elevations. This precip amount tapered to almost nothing at the south end of the range.
A further 15cm of snow came in throughout the range on Friday and Saturday. The snow has been redistributed by strong southwest and west winds. Windward ridges are stripped with loaded areas up to 50cm deep.
Previous gale force wind from the northwest and southwest has left old crusts and rock exposed on ridges and upper elevations.
The snowpack north of Stag Saddle is not well understood, with no direct observations. It is possible that above about 2300m very deep snow has accumulated.
Fine with morning frosts, possibly severe. High cloud developing in the afternoon.
Wind at 1000 metres
Westerly 30 km/h.
Wind at 2000 metres
Southwesterly 30 km/h, but 50 km/h developing at night.
Freezing level
1200 metres, lifting to 1600 metres at night.
While the new snow should go some way toward easing the sliding danger. Snowfall amounts are low particularly in the south. The old crusts may still be exposed and slick in plases.
Come prepared for a possible high sliding danger and assess each slope. Expect lots of rocks in the runouts.
Iceaxe and crampons are recommended.
Moderate
New Zealand Avalanche Advisory (NZ Mountain Safety Council)
