The new ash cloud passing over New Zealand is at a much lower altitude than previous ash plumes reports WeatherWatch.co.nz, as a result Air NZ has cancelled a number of flights to the South Island.

See the full story on which flights are affected here.

Head weather analyst Philip Duncan from WeatherWatch.co.nz says the new burst of ash cloud is much lower than the ones over the past few days.  “The reason Air New Zealand and other airlines have been able to keep safely operating these past few days was because the ash cloud ceiling was much higher.  Now it’s at a level where it’s below the summit of Mt Cook – passenger planes cannot safely fly at that low altitude”.

WeatherWatch.co.nz and Herald reporters have found it difficult trying to speak to authorities.

“The MetService and the National Institute for Water and Atmospheric Research referred inquiries for comment to each other and the Civil Aviation Authority” says a story in NZHerald.co.nz this morning.  WeatherWatch.co.nz was also told to contact CAA by MetService when we enquired about  technical aspects of the ash cloud yesterday.  CAA returned our call but the person couldn’t help us and gave us the number of their media spokesman instead, but it was afterhours and we were told to try again this morning.

WeatherWatch.co.nz says based on mapping provided by Australia’s Bureau of Meteorology (BOM) and the NZ MetService the ash cloud appears to be over the skies of Dunedin at an aviation height of just 10,000 feet (3048 metres).

Mt Cook is 3754 metres, although the ash cloud is not that far north west, meaning ash is still not falling over New Zealand.

The ash cloud then hugs the South Island’s east coast, heading north east at the same angle as the coastline.  Because of this, the ash cloud isn’t as likely to affect other airports, however Christchurch is right on the edge of the cloud so conditions there would be marginal says WeatherWatch.co.nz.

“To the west, out towards the Southern Alps, the sky is clearer and any ash out that way is much higher up, at 27,000 feet or 8000 metres” says Mr Duncan.

The new much lower ash cloud may also spread over Invercargill at times

Mr Duncan says the ash cloud may just touch the south eastern corner of the North Island, but points out there are no airports there and planes can easily fly to the west.  Wellington isn’t going to be affected, judging by the maps.

As far as further ash plumes are concerned Philip Duncan said this to NewstalkZB last night “It’s like a giant motorway in the sky, it’s an ever changing motorway so it’s hard to exactly pin point four to six days down the track exactly where that ash will go,”

“This is one thing no forecaster can tell you – and that’s when this volcano in Chile will stop erupting and while it continues to erupt New Zealand, Tasmania and Victoria will remain at high risk of being affected”.

– WeatherWatch.co.nz