A cyclone is a large scale air mass that rotates around a strong centre of low atmospheric pressure. There are 4 main categories of large synoptic scale cyclones.
Tropical cyclone - Originates in the tropics between 5° to 23° south of the equator. Non frontal, warm core.
Subtropical cyclone - Originates between 23° to 50° south of the equator. Non frontal, warm core.
Extratropical cyclone - Originates between 23° to 60° south of the equator. Frontal, cold core.
Polar low - Originates between 60° to 90° south of the equator. Frontal, cold core.
Examples of a smaller scale cyclone is a waterspout, tornado, mesocyclone, dust devil and fire twister.
Of the 4 large scale cyclones, only subtropical and extratropical cyclones have a direct impact on the upper North Island of New Zealand. Regional met agencies name a tropical cyclone which retains it's name when it transitions beyond the tropics into New Zealand waters.
Hauraki Gulf Weather only offers an opinion on the development and track of a cyclonic storm which can be followed in our cyclone outlook and current cyclones sections. We will also post opinions and updates on our our social media channels including real time updates on our twitter account . In accordance to the NZ severe weather code of conduct, all official warnings are issued by MetService under the Meteorological Services Act 1990.