Two Thumbs

Shifting winds and some new snow over firm surfaces may build new wind slabs.

Firm snow, ice and exposed rocks still present a significant hazard in many areas.

Use careful route selection around ridge-lines, gullies and above rocky runouts.

Mostly cloudy. Scattered showers, heavier and more widespread north of the Rakaia River in the morning. A few late morning and afternoon fine spells before low cloud and drizzle spreads in from the east in the evening.

WIND AT 1000m: Southwesterly 35 km/h, dying out in the afternoon.

WIND AT 2000m: Southwesterly 50 km/h, easing to southerly 30 km/h in the morning and dying out by evening.

FREEZING LEVEL: 1700m, lowering to 1400m in the morning.

Firm snow surfaces, exposed ice and rocks are widespread and will present a greater hazard than avalanches in areas previously exposed to the south-west gales. A slip or fall on steep terrain could have serious consequences, particularly above bluffs, in gullies or where runouts are confined.

Take extra care when travelling on hard snow, 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

• The snowpack structure is well understood.
• We are uncertain about forecast snowfall amounts.
• We are uncertain whether the wind will be enough to form new wind slabs.

No new avalanche observations over the past 2 days. Today's (9 Aug 26) rain below 1500-1600m has now frozen to old surfaces without any reported loose-wet avalanches observed.

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. Firm crusts and areas of wind-affected snow are widespread, with the most scoured and variable conditions found in the high alpine, and at the southern end of the range.

Sheltered terrain above 1600m continues to hold soft snow — cold wind-drifted snow can still be found in sheltered bowls that have escaped the southwest gales.

Sunny slopes have been softening from late morning.

Snow depth varies from 40-70cm, with deeper accumulations of 100-120cm in sheltered areas.

Small facets (weak sugary crystals) have begun developing around crusts in the upper snowpack and between layers of old wind slab, particularly on shallow shaded slopes. At present, these are not posing a significant problem. Below the crusts, the lower snowpack is well settled.

Northern end of range — north of Stag Saddle

The snowpack north of Stag Saddle is not well understood, with no direct observations. We expect that deep snow will have accumulated in sheltered areas above 1800m.