Heavy rain expected for New Years

File photo / NZ Herald

Civil Defence is on alert as more heavy rain is on the way for the Nelson region, while the Auckland district is also facing days of downpours over the New Year holiday.

Weatherwatch.co.nz says winds will reach gale force in marine areas around Auckland this afternoon as ex-cyclone Fina continues to move towards New Zealand.

Head analyst Philip Duncan said the low caused by the former cyclone puts Auckland in vulnerable position for heavy rain.

"Heavy rain is predicted in bursts on Thursday, Friday, Saturday (some thunder is possible - the weather may be more showery on Saturday) then more rain overnight and into Sunday, before clearing finally as we head into early Monday.

"New Years Eve may be a wet one in Auckland, with low cloud possibly affecting Sky City's fireworks - however we expect some lengthy dry spells in the mix too, fingers crossed we get one on Saturday night!

Even with the recent heavy rains, Mr Duncan said the dry spell in between was substantial enough to allow the ground to dry out, so it should absorb a fair amount of the rain.

But there is also a high risk of some surface flooding in the area, and while the risk of land slips in Auckland will be low to begin with, it is expected to become a moderate to high risk during the weekend.

Mr Duncan said that with so many holidaymakers in the upper North island camping in tents, it was important that the public make informed decisions about what is safe for them.

"Campers near streams, especially in hilly areas, should be aware of rapidly rising rivers over the weekend - and the potential, even though it's low to moderate, of flash flooding. People in vulnerable areas should have a back up plan to evacuate safely should rivers suddenly flood, or in case of slips and landslides."

Severe weather warning

Further south, MetService has issued a severe weather warning for the Nelson/Tasman, western Marlborough, and Mt Taranaki regions, with heavy rain forecast from tomorrow.

Rainfall is also expected to exceed warning levels in the Bay of Plenty and near warning levels in Northland and the Coromandel Peninsula. The Waikato and Wellington are also expected to receive heavy rain in the coming days.

The forecaster says a "moist, northerly airflow is expected to become established over the northern and central areas" of the country, bringing rain to much of the North Island and northern South Island in the coming days.

"This rain band is likely to bring significant amounts of rain to Nelson area especially during Friday," MetService weather ambassador Bob McDavitt said. "However, this event is not expected to bring as much rain or last as long as the event there in mid-December."
McDavitt said the main part of this front may bring a few bursts of heavy rain to some parts of the North Island on Friday.

"At this stage the low-pressure system is expected to weaken as it approaches Northland on Sunday, that's New Years Day," said McDavitt. "Rain should ease in Nelson during Saturday, but damp conditions are likely over much of the North Island for New Year's Eve, and heavy rain may be likely around Bay of Plenty until New Year's Day."

Up to 200mm of rain may fall over 36 hours from tomorrow afternoon in the Tasman District and western Marlborough, especially in the hills and ranges. Up to 120mm may fall in lower lying areas in that period, MetService says.

Up to 180mm of rain is possible in the 48 hours from midday tomorrow around Mt Taranaki.

MetService says the rain has the potential to cause rivers to rise rapidly and lead to flooding or slips, particularly around the Tasman District.

Nelson Tasman Civil Defence Controller Jim Frater said even a short sharp rain event could have an effect on areas already vulnerable.

"People should clear their drains of any debris. If anyone has particular concerns about the rain, people will be able to fill sandbags with sand for free from the Nelmac Nursery in Atawhai Drive, Nelson. The nursery will be open between 9am and 4pm today and tomorrow."

Areas being monitored in particular will include Cable Bay, Iwa Rd and Rocks Rd in Nelson, Ligar Bay, Pohara Valley and Wainui hill.

- NZ Herald staff