Tornados possible as heavy rain hits West Coast

Thunderstorms on the West Coast of the South Island could lead to tornados in the area, the MetService says.

A severe weather warning was issued this morning as heavy rain and thunderstorms hit western parts of the South Island.

The active front driving the downpours was expected to move up the country and heavy rain warnings were also in place for areas further north.

MetService forecaster Andy Downs said there had been no reports of wind troubles or small tornados but they were possible.

"The conditions we've got at the moment are conducive to that, so there's always an outside chance," Mr Downs said.

"Since last night we've had many thousands of lightning strikes on the West Coast being detected and that's also intensified the rainfall."

He said small tornados were quite prevalent on the West Coast and with a high numbers of thunderstorms the risk increased.

Heavy rain was expected to hit Buller and Nelson ranges from later this afternoon. Rain about Mt Taranaki was expected to continue through to Wednesday.

Mr Downs said while the rain about the Wellington area was not particularly heavy today, significant falls were likely in the Tararua ranges and northern hills of Wellington from tomorrow.

"It is set to really intensify tomorrow, particularly from the afternoon into the evening as the front moves north."

People in the area, particularly trampers, were warned streams and rivers would rise quickly and slips and surface flooding was also possible.

- NZPA