The snowpack is mostly stable.
Where there is new snow on higher elevation sunny slopes, daytime warming can increase loose wet risk.
Beware of pockets of windslab lurking on the northerly 1/2 about ridge top, or as a firm wind skin on new snow.
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.
Any southerly snow deposited on sun-facing slopes will sit over a slick melt-freeze crust sliding surface. Daytime heating may trigger loose-wet releases especially in steep terrain.
Further south in the range on Monday 17th natural loose wet avalanches were observed.
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 snowpack is isomorphic (uniform in temperature) and frozen except where subject to solar input during the day. At present, any stablity concerns exist primarily at surface/new snow interface level. A trace of southerly snow fell on the 15th and 16th driven by strong southerly winds. 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 Tuesday 18 August
Partly cloudy, with a possible shower.
Wind at 1000 metres
Southerly 40 km/h.
Wind at 2000 metres
Southerly gale 70 km/h.
Freezing level
1200 metres, lifting to 1500 metres for a time in the morning and afternoon.
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
New Zealand Avalanche Advisory (NZ Mountain Safety Council)
