An explosion in the tropics

Homes destroyed in Aitutaki during Cyclone Pat. Photo / Supplied

The tropics have exploded into action with 3 major cyclones in just a week. Cyclone Oli slammed French Polynesia over a week ago then Pat hit the Cook Islands last week. Today severe tropical cyclone Rene is going to tear across Tonga as a Category 4 storm (5 is the highest). Damage is expected to be widespread and severe. A category 4 storm can flatten a well built house in Florida – imagine the damage it can do to the infrastructure in a place like Tonga.

Cyclone Rene should also have an impact on New Zealand (although it will be an ex-tropical cyclone by the time it gets this far south). The tropical storm is headed directly towards us according to all the latest computer models. However it is going to weaken significantly once it moves south of Tonga over cooler waters. It will also contend with a large high pushing in from the Tasman Sea and will most likely stop short of us and turn away to the south east avoiding a direct hit with the North Island. As far as effects from the storm here I think cloud and fairly strong south to south east winds will spread across northern or north eastern parts of the North Island.

I don't think Rene will bring severe weather to New Zealand but any tropical system should be closely monitored. They tend to have minds of their own.

You can read the latest on Cyclone Rene in our new Tropical weather news section here.

For New Zealanders the biggest impact will probably be large swells in the east. If the storm is slow moving it will churn away offshore and drive in large swells to eastern parts of the North Island from Northland down to Hawkes Bay. Good news for surfers. For swimmers it's very important to realise that even though a storm may be well away from land with perhaps no visible signs of severe weather near you the ferociousness of a storm like this can create big waves and dangerous rips. In America last year a hurricane that was near Bermuda and didn't even produce cloud for America killed a number of swimmers right along the eastern US seaboard due to the dangerous rips and waves that were generated hundreds of kilometres offshore.

A deep low over the ocean is a bit like dropping a rock in a pond...large swells ripple out in ever increasing circles for quite a distance.

We'll be monitoring Rene closely – and the next tropical storm which may well form as soon as next week. The next name is Sarah.