Residents of the South Island’s West Coast should prepare for a wet Friday and Saturday as a “tropical disturbance” will bring periods of heavy rain through the region.

The disturbance is currently located near New Caledonia but is forecast to move south by the end of the week.

Niwa said, although the track is currently uncertain and could change, it is likely to hit parts of the upper and central parts of the South Island and potentially the east coast of the South Island.

Niwa meteorologist Seth Carrier estimated 100mm could be pretty widespread on the upper and central west coast.

 “I would not be surprised to see up to 200mm of rain in the higher terrains.”

However, he said it does look like the disturbance won’t stick around for very long.

“We have had events over the past few months, including Cyclone Gabrielle, that have been quite slow-moving that have contained a lot of sustained rainfall over long periods of time,” he said.

“The fact that this will move through New Zealand quickly is quite good news.”

Carrier estimates there will be about 12-18 hours of the heaviest rainfall.

He said it does not look likely to turn into a tropical cyclone.

“It’s completely understandable that when something notable like a cyclone happens, people are on their toes,” he said.

“I’m not seeing a Gabrielle situation, and it doesn’t look like the east coast of the North Island will be affected by this.”

Niwa warned South Island residents to keep an eye on the forecast over the next few days to see any changes.