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The Avalanche Advisory said storm slabs presented the greatest risk above 1800m, after up to a metre of new snow fell overnight on Thursday.
Avalanches large enough to kill, injury or bury people have been sighted down to 1200 metres since then.
The Advisory said that careful snowpack evaluation, cautious route-finding and conservative decision-making was essential.
The alert was valid until Monday night.
According to the MetService, northwesterlies rising to gale are expected in exposed places at Aoraki Mt Cook tonight. Rain is expected to develop tomorrow morning, possibly heavy in the afternoon, with severe gale in exposed places.
There was also a heightened risk of avalanches in high alpine parts of Mt Hutt and the Craigieburn Range.