Sub-tropical deluge drifting slowly down NZ
WeatherWatch.co.nz has put out an alert for slow moving intense bands of rain this afternoon which are sub-tropical fuelled.
Downpours heavy enough to cause localised flooding on roads, in basements and overwhelm gutters are a possibility across Northland, Auckland, Waikato and Coromandel Peninsula this afternoon and into early evening in some areas.
The intense rain is slow moving, which increases the chances of flooding.
WeatherWatch.co.nz head forecaster Philip Duncan describes the rain bands as "evolving".
"When you have moisture-rich subtropical air combining with peak daytime heating plus a developing low moving in, it's the perfect recipe to create heavy downpours.
"The rain bands are changing shape and size and intensity every few minutes as it slowly moves down the upper North Island."
The evolving nature makes some areas get more intense rainfall than others - and the hills and ranges of NZ can increase rainfall in some areas while drying it out in others. The evolving nature of the downpours also means an intense downpour tracking in one direction can fall apart - or get worse.
Philips the downpours as both good news and bad.
"Our farms, our market gardens our home gardens and rain water tanks all need this rain. In fact as intense as it is, it's unlikely to make up for the rainfall deficit in many upper North Island areas but it will be very welcome.
"However, when rain is this heavy and slow moving it can cause localised flooding and increase the chances of vehicle accidents and even water damage to property."
The downpours are moving through until this evening. Surrounding regions may also be impacted.