A tramper has died after an avalanche was triggered on Mount Cook earlier today.

Police confirmed the incident occurred around 1.30pm and involved three trampers.

One of those died in the incident, a second person has minor injuries and the third person was uninjured.

Mid-South Canterbury area commander Inspector Dave Gaskin told stuff the third tramper with the pair had stayed behind at the Sefton Bivouac hut because they were sick.

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The avalanche took place on the Eugenie Glacier, just below the Footstool mountain peak.

The person who sustained minor injuries was transported to Twizel for medical treatment.

Police say they are still at the scene of the avalanche.

A New Zealand Mountain Safety Council (MSC) spokesman told the Herald it's too soon to understand how the avalanche was triggered but there was a moderate forecast risk.

"There was a moderate forecast at the time for that region, which is the second-lowest rating and just above low," the spokesman said.

"What that means is natural avalanches are unlikely, human triggered avalanches are possible, usually small avalanches in specific areas or large avalanches in isolated areas.

"Just because it's a moderate danger doesn't mean there's no danger - that's one of the things to really get across to people."

Metservice reports Mount Cook's weather for today was fine spells, with a chance of a shower or two with light winds and a high of 18C.

The MSC spokesman said there was a risk for loose wet avalanches at the time above 12,000-metres.

"There's various types of snowpack conditions, so loose and wet is as it sounds,' he said.

"It's quite a slushy, icey mixture, that condition can mean that sort of avalanche can run a lot further than a typical slab avalanche which is nicely bound together."

The latest tragedy comes after two mountain guides were killed last month in an avalanche on Mt Hicks that also buried adventurer and philanthropist Jo Morgan.

Jo Morgan is the only survivor of an avalanche that killed her two climbing partners on Mt Hicks last month. Photo / Facebook
Jo Morgan is the only survivor of an avalanche that killed her two climbing partners on Mt Hicks last month. Photo / Facebook

Morgan was lucky to escape with her life and told media at the time she was "gobsmacked" to be alive after digging herself out.

Her climbing partners Martin Hess and Wolfgang Maier - who are both originally from Germany but had become New Zealand residents – were not so lucky.

Morgan had been roped to the two experienced mountain guides when the avalanche hit, but she was unable to find them after being sent tumbling up to 200m down the mountain.

"None of us had any control over it."

Morgan was rescued after setting off a personal locator beacon.

More to come.