Heavy rain set for Bay of Plenty

Rotorua and the Bay of Plenty are set to receive scattered heavy showers and possible thunderstorms this afternoon and evening, MetService forecasts.

Forecaster John Crouch said daytime cloud build-ups are producing scattered heavy showers about inland Bay of Plenty, and a few of these showers may develop into thunderstorms this afternoon and evening.

"The most likely area for thunderstorms is about inland Bay of Plenty, east and southeast of Rotoroa," Mr Crouch said.

"If thunderstorms do eventuate they will be slow-moving, and therefore have the potential to be severe producing localised downpours with rainfall rates in the 25-40mm/hr range."

He warned that rainfall of this intensity can cause flash flooding, especially around low-lying areas such as streams, rivers or narrow valleys, and may also lead to slips.

Driving conditions will also be hazardous with surface flooding and poor visibility in heavy rain.

MetService is also forecasting showers for much of the country for tomorrow and Friday.

A low developing in the north Tasman Sea is expected to move towards the South Island on tomorrow while a moist northeast flow spreads onto New Zealand. On Friday a front should sweep across New Zealand while the low move southward over the south of the South Island.

The flow over the country should turn northwest following the front.

During the second half of tomorrow and through Friday, rain is expected over much of New Zealand.

Rain is expected to set in tomorrow afternoon and then ease on Friday for the Coromandel Peninsula and western Bay of Plenty.

For Nelson and northern parts of Marlborough, rain should commence tomorrow afternoon or evening and be heavy at times through Friday morning.

For Westland, rain is expected to set in early Friday with the heaviest falls during Friday afternoon and evening.

Further rain is expected in the north and west of both islands during the weekend with possible further heavy falls, particularly for Bay of Plenty and the South Island west coast.

- NZ Herald staff