40-50cm of new snow has just fallen across the region with strong winds.
Wind slabs may still be reactive and could continue to form with forecast strong winds on Sunday
Evaluate the snow and terrain carefully, avoiding features of concern
More likely above 1800m, on west, north and east-facing aspects around specific terrain features such as steep roll-overs, under ridgelines or around other terrain features, recently formed wind slabs may still be reactive.
Strong to gale southerly winds and 40-50 cm of recent storm snow mean recent wind slabs could easily be over 100cm in depth.
Ongoing wind transport may continue over Sunday.
Evidence of multiple Sz 2-3 natural storm and wind slab avalanches was observed to have run during the July 30-31st storm. Around the Forbes and Richardson Mountains these ran on mostly SE aspects between 1900-2100m. Image below shows one on Mt Earnslaw east aspect.
If you see any recent avalanche occurrences or have any relevant snowpack information or photos, you can share them via the Public Observations link on the NZAA home page.
Up to 50cm of new snow fell between July 30 and 31. Initially, with strong northwest winds on the 30th, this also had a good going-over with strong southerly winds on the 31st. Many sheltered areas appear to have been left unscathed, and other more exposed slopes and features were stripped back to old layers. Some investigation showed this new load was bonding relatively well.
Previously the snowpack was still shallow, approximately 60- 70 cm below 1700m and 120cm at 2000m. Crevasses are still very open, and many rock features are still visible, particularly on west-facing aspects.Although the pack appears consolidated, the Aspiring region is very large, and there is still limited data. Caution should still be taken, particularly in steeper, more extreme terrain where unknown weaknesses may exist.
Mt Aspiring National Park Forecast
Forecast for Sunday
A few showers becoming widespread in the afternoon. Snow to 1200 metres.
Wind at 1000 metres Southwesterlies 35 km/h.
Wind at 2000 metres Southwesterlies 45 km/h, rising to gale 65 km/h about midday.
Wind at 3000 metres Southwesterlies 45 km/h, rising to gale 65 km/h about midday.
Freezing level About 1500 metres.
Issued: 10:34am Sat 1 Aug
West aspects may have been stripped back to old ice layers with recent strong winds. Depending on your objective, an ice axe and crampons could be necessary.
Moderate
New Zealand Avalanche Advisory (NZ Mountain Safety Council)
