Tropical cyclone Ruby is currently bearing down on New Caledonia before it's expected to move south towards New Zealand.
According to an update from WeatherWatch at about midday on Tuesday, Ruby has made landfall on New Caledonia's western side and is tracking towards the middle of the island, near the capital of Noumea.
It's moving "quite fast", according to the forecaster. The faster it moves, the lower the rainfall totals will be, it says.
"Wind speeds may still climb further, although it's not expected to strengthen very much – mostly due to low pressure zones in the NZ are now taking some of Ruby’s energy.
"However, sustained winds with Ruby are estimated to be at 110km/h an hour right now, making it a 'strong' Category 2 Cyclone…it's just 8km/h away from reaching Category 3 power. The focus on if it's Cat 2 or Cat 3 is fairly insignificant at this point, as the storm has arrived and it will either retain current power or only get a little more powerful."
It's expected to clear New Caledonia on Tuesday night, before moving south, tracking north-east of Aotearoa around Thursday.
"It's likely to get swallowed up by a 'mega' low in the NZ area which will contribute to more wind and rain in the NZ area, but not as a direct single storm moving in. In fact, the centre of Ruby’s remnants may well miss NZ out to the east."
Metservice says the system will move past the upper North Island "as a deep low" with most outlooks suggesting it will remain offshore.
"But there remains some uncertainty regarding how close to New Zealand the system will come."
WeatherWatch forecasts the next two days will still see "a mixture of dry spells, drizzle patches and big downpours", which some regions were blasted with on Monday.
"These downpours have already led to localised flooding in Manawatu overnight and more of these downpours can be expected [on Tuesday] across the North Island and into the upper half of the South Island as they become more widespread.
"Low-pressure zones in the Tasman Sea are siphoning some of the energy out of TC Ruby, bringing slow-moving heavy tropical-fuelled rain to parts of New Zealand in the coming days, but especially the next 36 hours."
WeatherWatch says there is "flooding potential" on both the North and South Island. That includes the north-eastern part of the South Island, "as far south as Banks Peninsula and as far west as Tasman". Christchurch could also "be exposed to some flooding risks".
The regions most exposed to the heaviest of the incoming rain and flooding risks are Bay of Plenty and East Cape.
From Tuesday to Wednesday, total rainfall of between 50-100mm "will be common" across the North Island and upper South Island, with falls potentially exceeding 150mm in Bay of Plenty, Taranaki and Tasman. Wind gusts of 80km/h are possible in exposed areas of Bay of Plenty, Gisborne, Tasman and West Coast.
On Thursday, Christchurch and nearby surrounding areas are likely to see 30-50mm of rain, "enough to cause localised flooding in low-lying areas depending on how quickly it falls".
Despite the rain, it's going to be a warm few days. WeatherWatch says while maximum temperatures will be "much cooler" than normal across the eastern side of the South Island through to Friday, other areas "will experience warmer than normal highs".
"Minimum temperatures will be above to well above normal across the North Islands and western coast of the South Island from Tuesday to Thursday before dropping to below normal across the country from Friday."
There are currently a large number of Heavy Rain Warnings and Watches issued by Metservice for parts of New Zealand. That includes a Heavy Rain warning for between 9pm on Tuesday and 3pm on Wednesday for Bay of Plenty. It's forecast that 130-180mm of rain will accumulate inland here and about 70-100mm on the coast.
