Dangerous surface conditions currently. An icy rime crust exists above 1400 metres, mostly on south aspects, but will be elsewhere. A high level of alpine skills will be required. Wind slabs may form on south aspects. A weak weather feature moves into the region over the next 24 hours. Visibility will be limited, and the weather will be unpleasant.
Wind slabs may form as new snow starts to be transported above 1700 metres in elevation. This wind slab will be mostly on south aspects and low volume. Triggering will be possible on higher-angle slopes. Maintain a conservative mindset when approaching any loaded slope lacking support.
Loose wet avalanche activity will become a possibility once rain starts to affect the snow surface. Forecasted rain is not significant, however, enough to reduce surface structure. Loose wet activity will be greater on northern aspects, where surface penetrability and rain intensity are higher.
No natural or human-triggered avalanche activity has been observed or reported over the previous 24 hours.
On southern aspects, an expansive rime crust is the dominant snowpack feature currently. This is a robust surface deposit, which is hard and slick. Older wind slabs have gained strength and have become consolidated. The snowline is about 1400 metres elevation currently. The estimated threshold is slightly higher at around 1500 metres. Snow cover threshold, enough snow to bury bed surface irregularities, and avalanches can run.
Cloudy periods with a few showers, turning to rain at night. Possible snow to 1700 metres before dawn. The winds will be light and northerly tomorrow, the 13th of July, but will become moderate by the afternoon. The freezing level is 1600 metres elevation rising to 2000 metres over the next 24 hours. A ridge of high pressure over New Zealand moves away to the east today as a broad trough approaches from the west; the trough then moves across the South Island on Monday.
Rime crust on southern aspects is slick, hard, and unforgiving. These types of conditions demand a high level of skill and competency. The consequences of a fall and slide will be severe. Plenty of hazards, such as exposed rocks and cliff bands, exist. It is essential to carry the appropriate gear, crampons, and an ice axe. Be prepared and read the surface conditions as you travel. Recommend a conservative mindset.
Low
New Zealand Avalanche Advisory (NZ Mountain Safety Council)
