Cyclone Neil forms, poses direct threat to Tonga today, another bigger storm possible days later (+3 Maps)


Tropical Cyclone Neil has formed east of Fiji and will track southwards towards Tonga, caught up in a large area of tropical unrest that will remain north of New Zealand for possibly the rest of February, producing further lows and cyclones.

The Fiji Met Service named the storm on Saturday afternoon. The cyclone is not expected to become a major storm but should retain Category 1 status (or near it) when it passes over Tonga later on Sunday and early Monday. The Fiji Met Service doesn't expect it to be any stronger at this stage. Heavy rain and strong winds/gales are likely for about 24 hours there. 

WeatherWatch.co.nz says Neil won't have a long life as it tracks southwards away from the tropics and over cool, less favourable conditions - weakening quickly early next week.

Neil is one of three tropical lows between NZ and the Fiji/Tonga area right at this moment. Two other lows will merge and brush past East Cape later this Sunday bringing some rain that may penetrate further west for a time, as far west as Coromandel Peninsula and maybe even eastern Northland.

The two lows merging will actually weaken further on Monday just east of East Cape and falls apart almost entirely on Tuesday as it tracks away from the country - that is until the remnants of Neil catch up and the three lows merge near the International Date Line well east of NZ. 

Another low is developing behind Neil and may be bigger.

The next low will follow behind Neil but is caught up in a much larger pool of low pressure that stretches from the Coral Sea near Queensland well out towards American Samoa - basically the tropics North West, North and North East of NZ.

WeatherWatch.co.nz says this next storm behind Neil will be pulled in a large clockwise fashion and may end up tracking west toward New Caledonia - different to Neil's direct south track.

So what does this mean? It means the next storm may linger much longer north of NZ and dance around another low creating uncertainty of future tracking and strength.

The jury is still out on whether or not the following storm may bring rain to northern NZ - some modelling says yes, others aren't so positive. At this stage it looks around 60% likely according to WeatherWatch.co.nz. It should become much clearer this coming week and we'll have daily updates in both news and videos. 

The first two maps below show the tracking and threat areas for Cyclone Neil as of Saturday evening, courtesy of Fiji Met. The third map shows one possible outcome this Friday as another storm behind Neil may send some rain towards NZ - but it depends on high pressure to our west and east at the time (see the detailed information written below that map for more).

- Next Friday shows another storm, after Neil, this time directly north of NZ and not well out to our north east. It is not locked in yet so if you need rain check back for updates this coming week. This is the current GFS (American) map showing the low centred well north of NZ but possibly bringing rain as far south as the upper North Island.

The reason why there is so much uncertainty about if this low will bring rain to NZ is due to the large highs both east of NZ and west, over Tasmania...if the highs leave a gap between them (as the map above indicates) this will allow the tropical rain to drop south. If either of the highs are closer to NZ then that limits the chance of that tropical rain dipping far enough south to reach us.

- WeatherWatch.co.nz