Despite a fine morning, surfaces will remain frozen and a Southerly will hit the range in the afternoon.
Make a conservative plan that includes the option to back out of steep, lee-ward terrain by midday if slabs develop.
Only in the far North of the range, in terrain above 2200m, small isolated pockets might still lurke.
However, as the Southerly moves in the wind increases and if more snow than forecast falls, then new windslab might build over the firm frozen surfaces.
Look out for smooth, rounded pillows of wind-drifted snow, changes in snow texture and hollow-feeling slabs over firmer old snow.
No new avalanches onserved on 14 Aug.
From 12-13 Aug:
North of Round Hill ski area: numerous natural, loose wet avalanches of seize 1-2 in high elevation steep terrain.
Cass Valley: numerous natural, loose wet avalanches of size 1-2 avalanches, mostly on East to Northeast aspects from steep terrain at 2000m-2200m.
If you see any activity on the Two Thumb Range, please make a public observation. It helps us to produce accurate forecasts.
Southern end of range — south of Stag Saddle
Ridge-lines and slopes exposed to the south-west, have been heavily scoured, and mostly stripped back to old crusts, or even bare rocks and scree on upper ridges.
All surfaces have gone through a melt-freeze cycle and the Northern half has softened in the sun, but will refreeze in clear night. Only above approximately 2200m dry snow may have survived the warm weather. The crusts are mostly decomposed and the lower snowpack is well settled and consists of mainly meltforms or round crystals.
Snow depth varies from 40-50-cm, with deeper accumulations of 100-120cm in sheltered areas.
Northern end of range — north of Stag Saddle
The snowpack North of Stag Saddle is not well understood. We only have one observation from Monday 10 Aug from the area around Captains Peak and Mt Toby, reporting only slightly more snow than around Camp Stream or the Richmond Range, with very little old avlanche debris observed. The group of recreationists did report a similar snowpack to the South.
A fine and frosty start. Scattered rain developing late morning, with snow lowering to 500 metres from late afternoon.
WIND AT 1000m: Southeasterly 30 km/h, rising to 55 km/h north of the Mackenzie Basin in the afternoon.
WIND AT 2000m: Southerly 30 km/h, rising to 55 km/h in the evening, but to gale 65 km/h in exposed places north of the Mackenzie Basin.
FREEZING LEVEL: 1800m, lowering to 1400m in the morning, then to 900m in the afternoon.
Note: the brief band of precipitation on Saturday afternoon and night is forcast to only bring 5cm in the south and maybe 10cm in trhe North. However, it is a South-East systems and those are often underforecast for the Two Thumb Range.
The warm weather has softened all surfaces. However, they will re-freeze with a clear night. A slip or fall on steep terrain could have serious consequences. Many run out areas are now bare rock or scree.
Assess runout zones before committing to steep slopes, and carry equipment appropriate for firm alpine conditions, such as crampons and an ice axe. Conservative route selection remains the most effective way to manage these hazards.
Moderate
New Zealand Avalanche Advisory (NZ Mountain Safety Council)
