MetService keeping an eye on two tropical disturbances in Pacific
There are no tropical cyclone warnings for the South Pacific, the MetService says.
Online forecasting and some media reported a new tropical cyclone warning for New Zealand.
There are none at present.
There are, however, several separate weather systems in the vicinity of New Zealand - a low pressure system forming to the west of the country, and two tropical disturbances in the south Pacific.
Those disturbances - too diffuse to be defined as cyclones - are east of Tonga near Niue and northwest of Fiji.
CURRENT STATUS OF CYCLONE ACTIVITY
There are presently no tropical cyclones in the Coral Sea or South
FORECAST TO 1200 UTC 07-Apr-2017
Tropical Disturbance TD19F (1000hPa) was analysed near 20.4S 170.6W
at 060000UTC, near Niue, or about 250nm east of Tonga, moving south at around 3 knots.
The system should become slow-moving through Saturday, before turning slowly west-southwest from Sunday through Monday.
Environmental conditions are currently unfavourable for any
significant strengthening, but as the system begins turning westwards
during days 4-5, wind shear decreases, thus potentially allowing
TD19F to gradually strengthen.
There is a LOW chance of the system developing into a tropical cyclone through Saturday,increasing to LOW-TO-MODERATE on Sunday and Monday.
Tropical Disturbance TD20F (1004hPa) was analysed near 12.4S 175.8E
at 060000UTC, or about 310nm north-northwest of Nadi, and was
slow-moving. The system lies in a region of mildly favourable
environmental conditions, and global models are picking this system
to gradually intensify during days 4-5 as it begins moving soutwards
towards southern Vanuatu.
The potential for this system to develop into a tropical cyclone is LOW for days 1-3, increasing to MODERATE from Sunday evening onwards.
OUTLOOK TO 1200 UTC 10-Apr-2017
Tropical Disturbance 19F is expected to remain near Niue through
Saturday, then beging moving slowly westward towards Tonga on Sunday
and Monday. The chance of TD19F intensifying into a tropical cyclone
is LOW for Saturday, increasing to LOW-TO-MODERATE from Sunday
onwards. While TD19F may not reach TC strength over the next 5 days,
the system is expected to remain a significant tropical depression,
which would likely generate high rainfall amounts due to its
Tropical Disturbance 20F is expected to drift south-southwest, moving
close to southern Vanuatu during Sunday and Monday. The chance for
TD20F to develop into a tropical cyclone is LOW through Saturday,
increasing to MODERATE from Sunday evening onwards.
A MetService tropical cyclone bulletin says the chance of the system near Niue intensifying into a tropical cyclone is low to moderate over the weekend but, as a significant tropical depression, it is expected to bring heavy rain.
The other tropical disturbance is expected to move south-southwest towards southern Vanuatu on Sunday and Monday.
MetService forecaster Matt Ford said there were two tropical disturbances being monitored by the Fiji authorities.
"Neither of them are tropical cyclones at the moment but they are promising conditions.
"Possibly the one that is getting everybody's knickers in a twist is tropical disturbance 20F [near Fiji moving towards Vanuatu].
"There are no tropical cyclones. To the northeast of Vanuatu it looks like it will move towards Vanuatu and it's likely it will reach strength.
"What happens to it after...we're really talking about Easter weekend. This weekend it's likely to move across Vanuatu.
"Around Monday or Tuesday it's deciding what to do. There's quite a range of possibilities and outlooks at this time. We're looking at various computer models and guidelines. Those kinds of possible forecast outcomes can change.
"There are massive amounts of uncertainty when it moves out of the tropics.
"There's a possible scenario which brings it towards New Zealand. The story is what's going to happen to Vanuatu.
"We're keeping an eye on it next week."
Ford said there was another low pressure system moving across the Tasman towards New Zealand.
This system was expected to bring some heavy rain next week.
The Fiji Meteorological Service tropical cyclone forecast largely echoes the New Zealand meteorologists.
Strong winds, heavy rain, and thunderstorms are forecast for Niue over the weekend.
Meanwhile, the National Institute of Water and Atmospheric Research says Auckland recorded the equivalent of normal April rainfall - 84.6mm - in 14 hours from Tuesday evening to Wednesday morning.
Many parts of the country had two or three times the normal April monthly rainfall in just two or three days.
Hamilton had its second wettest start to any calendar year on record since 1907 with 537 mm of rain.
The torrent dumped 164mm of rain on Tauranga while Whakatane had its wettest April day on record since 1952.
Kaitaia has its second wettest start to any calendar year on record since 1948 with 567 mm.
Wellington Airport recorded 72 mm in one day between 9.00am Wednesday and 9.00am Thursday, making it the wettest day at the airport in almost a decade.
The Niwa forecast said the country was stuck in a pattern favouring low pressure systems to the west and sweeping high pressure to the south and east.
Niwa forecaster Ben Noll said another band of heavy rain was expected on Tuesday for the North Island and north and east of the South Island.
"Furthermore, a tropical disturbance north of Vanuatu is being monitored for strengthening over the weekend into early next week.
"There is some uncertainty regarding the eventual strength and track of the tropical system, although its progress will need to be watched closely as it could influence New Zealand's weather later next week," he said.
However, Philip Duncan, forecaster for Weather Watch, said looking at the international models, two tropical cyclones may be forming north of New Zealand next week.
He was fairly confident that one of these would not reach the New Zealand's shores, but the other might directly impact the North Island.
"That's the sort of disclaimer with a long-range forecast like this. The models can change, and they do change, and we're not locking this in yet."
An ex-cyclone would bring with it tropical moisture, and tropical instability, he said.
"The combined concern is that the Tasman low sucks down the cyclone and you end up with a bit of a double whammy, and that's a possibility."
Even though it's not a certainty, with rivers already full, and the ground saturated, Duncan said people might want to be prepared.
"The entire North Island is now wetter than average, and two months ago the entire North Island was in drought."