The snowpack remains mostly stable.
Strong southerlies may still be transporting snow, so beware firm windslab on northerly slopes, especially about ridge tops.
Where there is new snow on higher elevation sunny slopes, daytime warming can increase loose wet risk.
Southerly snow blown onto firm north-facing slopes may have formed pockets of wind slab. Remember the indicative signs, including changes in the density of snow and firm pockets that sound hollow or drummy.
Wind crust is a sign that windslab is forming, especially where you see blowing snow.
Any southerly snow deposited on sun-facing slopes will sit over a slick melt-freeze crust sliding surface. Snow is settling quickly, but take care in steep terrain.
Elevated sliding danger currently exists throughout the Park. Melt-freeze crusts are the primary snow surface type at present and the present cold southerly winds limit daytime warming and snow softening. Crampons and an ice axe are a good idea. Putting crampons on early increases your safety margin massively.
High
Further south in the range on Monday 17th natural loose wet avalanches were observed but none on Tuesday 18th.
Park user observations provide important information. Please help us.
If you see anything, please report it in the public observations section of the NZAA website.
In most parts of the Park the main snowpack is isomorphic (uniform in temperature) and frozen above ~1600m. Below that, a melt freeze crust caps weak isothermic snow. For now, any stablity concerns exist primarily at surface/new snow interface level above 1600m. Below that the primary character is thin, weak snow. A trace of southerly snow fell on the 15th and 16th driven by strong southerly winds and this snow has been redistributed at higher elevations into hollows with a max depth of ~30cm. At present they remain soft and no reports of slab character have been received. However, isolated pockets of windslab might exist about ridge lines and downslope terrain features lee to the southerly wind and will sit on a very firm melt-freeze crust surfaces. Over the last few weeks winds from all around the compass have stripped higher elevation peaks and ridge lines back to either ice or very firm and now frozen snow. The threshold for avalanches is estimated at around 1500m in the west, tapering east.
Forecast for Wednesday 19 August
Mostly cloudy with the odd morning shower. Fine spells developing in the afternoon.
Wind at 1000 metres
Southerly 40 km/h, dying out in the afternoon.
Wind at 2000 metres
Southerly gale 70 km/h, easing to southwesterly 30 km/h in the afternoon.
Freezing level
1300 metres, lifting to 2100 metres in the afternoon.
New Zealand Avalanche Advisory (NZ Mountain Safety Council)
