Fiji is "smack bang in the firing line" of a major tropical cyclone that could be life-threatening for some on lower-lying islands.
Tropical cyclone Yasa, the first severe tropical cyclone of the 2020/21 South Pacific cyclone season, is steamrolling its way towards Fiji.
Yasa has just been upgraded to a category 5 storm with sustained winds at 200km/h and gusts reaching 270km/h.
Weatherwatch says models show Fiji to be "smack bang in the firing line" of the potentially devastating storm, with the main risk being from Thursday afternoon until Saturday morning.
"Over the past few days the tracking of Yasa over Fiji has started to shift further east. This exposes more parts of Fiji and more people to the power of this storm. If it pulls more to the west that could reduce the impact in the eastern side," Weatherwatch says.
It said the storm will likely take more than 24 hours to move through the region, increasing the chance of damage.
"A storm this powerful can destroy buildings, uproot trees, strip trees of leaves, cause slips, flooding and coastal inundation. Yasa is a life threatening event for those in low lying islands in the Fiji group."
Weatherwatch's forecaster Philip Duncan says over the next three days, some areas around Fiji will be experiencing 200-300mm of rain. A few unlucky spots could see up to 400mm.
"That's a lot. That causes slips, flooding just on its own."
Waves of up to 10m can be expected in western areas "on top of the storm surge".
The Fiji Meteorological Service on Tuesday night put a Tropical Cyclone Alert in place for northwestern island groups. It also forecast the storm to reach a category 5 level as it nears Fiji.
After Yasa moves over Fiji, there is a 40 percent chance its remnants will have some impact on New Zealand next week or weekend, according to Weatherwatch. But it won't be "the same beast" that hits Fiji.
"Computer modelling, data we trust and experience we’ve gained over the decades suggests NZ could get some sort of rainmaker - but there is much uncertainty about timing and even if both main islands would be impacted."
There is just a 20 percent chance Yasa will prompt severe weather warnings in NZ if it reaches us.
"Remember, while a moderate risk of [what will then be] ex-cyclone Yasa reaching NZ, there is only a low risk this may be a 'storm' still by then in our part of the world."
Meanwhile, another cyclone, Zazu, is dropping from a category 2 storm to a category 1. This comes as it moves south over cool sea temperatures and less favourable conditions.
"The storm still poses some threat to Tonga and Niue today. For Tonga the main risk is strong winds and dangerous seas," Weatherwatch says.
"For Niue the main threat is for damaging gales, heavy rain, thunderstorms and dangerous seas. Niue looks most exposed today. Zazu poses no direct threat to any nation from tomorrow."
