Wet slab avalanches are now an increased possibility following the recent heavy snowfalls on Queenstown's mountains, say the Mountain Safety Council.
Avalanche programme assistant manager Gordon Smith said large avalanches had been observed at the higher levels of mountains around Queenstown.
"With that last storm that came in here, it's been a pretty active cycle of avalanches," Mr Smith said.
A large size three was documented above Lake Alta, which is underneath Double Cone, and "where it broke away was over a metre and 200m wide, so that's a lot of snow to come down".
Typically, avalanches were of the "wind slab" variety, and after the snowfalls "wet slab" had become a possibility.
"If the snow comes in and it's warm and wet . . . it's going to destabilise. That's what our advisers have highlighted - the wet slab.
"It will make the snow very heavy and it can only take so much weight before it gives way."
A wind slab avalanche was essentially a hollow layer of snow underneath a wind-transported dense layer and was characterised by big blocks of falling snow as opposed to the snowballing effect of wet, loose snow.
"If you are walking up that dense layer, it can collapse."
Different areas of the mountain posed higher risks since wind-blown snow often ended up in sheltered areas and this risk was made apparent on the Mountain Safety Council website's diagrams.
A small amount of snow also posed a danger because it could mean fragile or unstable snow.
The Mountain Safety Council website listed the highest risk for each area. Queenstown had been given the "considerable" danger warning for most of August and September.
Avalanche programme assistant manager Gordon Smith said large avalanches had been observed at the higher levels of mountains around Queenstown.
"With that last storm that came in here, it's been a pretty active cycle of avalanches," Mr Smith said.
A large size three was documented above Lake Alta, which is underneath Double Cone, and "where it broke away was over a metre and 200m wide, so that's a lot of snow to come down".
Typically, avalanches were of the "wind slab" variety, and after the snowfalls "wet slab" had become a possibility.
"If the snow comes in and it's warm and wet . . . it's going to destabilise. That's what our advisers have highlighted - the wet slab.
"It will make the snow very heavy and it can only take so much weight before it gives way."
A wind slab avalanche was essentially a hollow layer of snow underneath a wind-transported dense layer and was characterised by big blocks of falling snow as opposed to the snowballing effect of wet, loose snow.
"If you are walking up that dense layer, it can collapse."
Different areas of the mountain posed higher risks since wind-blown snow often ended up in sheltered areas and this risk was made apparent on the Mountain Safety Council website's diagrams.
A small amount of snow also posed a danger because it could mean fragile or unstable snow.
The Mountain Safety Council website listed the highest risk for each area. Queenstown had been given the "considerable" danger warning for most of August and September.
