Central North Island prepares for floods as wild weather strikes

The top half of the North Island is set to be hammered by 120km/h gales and heavy rain as the already sodden Bay of Plenty is put on flooding alert.

The country is in for days of a fierce winter storm with damaging gales, intense rain and snow set to descend in a matter of hours. As much as 160mm of rain is expected to fall in Canterbury and eastern Otago. The Bay of Plenty is bracing for 100mm in the space of 12 hours overnight.

MetService has issued widespread watches and warnings ahead of a storm the forecaster is describing as "significant".

People are being told to prepare for flooding, slips and destruction from strong winds in the north. There's also likely to be more snow chaos in the south and widespread travel disruption across New Zealand.

A swathe of warnings stretching across the length and breadth of New Zealand are now in force.

Upcoming #WinterWeatherWhammy may bring parts of the eastern South Island an entire month's worth of rain (or more) on Friday 🌧🌧🌧 pic.twitter.com/ijAFelfV0U

— NIWA Weather (@NiwaWeather) July 19, 2017

Strong winds are set to lash the top of the country today as the weather front sweeps across.

Auckland and the Great Barrier Island are expected to be thrashed by 100km/h gusts this afternoon.

Auckland: 2-3 hours of heavy weather this aftn/evening. NE gusting 100km/hr & brief heavy rain, https://t.co/tks2Q4pbWD @AucklandCDEM ^GG pic.twitter.com/9hUE1lt8Fo

— MetService (@MetService) July 19, 2017

The heaviest rain is expected to strike Bay of Plenty with the region also contending with even stronger 120 km/h gales.

Bay of Plenty Civil Defence says rain is expected to become heavy from 3pm with up to 110mm expected to fall overnight.

The highest rain is likely to be east of Opotiki but downpours would be intense right across the bay, warned a civil defence post.

"Beware of hazardous driving conditions, with slips and surface flooding possible. For those of you just getting into calving, remember the ground is already quite wet, take care in the paddocks and make sure you have a mate who can tow you out," posted the authority.

Be Prepared: Heavy rain expected across BOP this afternoon. Please take extra care & #DriveToConditions ^TP
https://t.co/9ClWNWhu0i

— Waka Kotahi NZTA Waikato/BoP (@WakaKotahiWaiBP) July 19, 2017

Meteorologist Robert Kerr said strong northeast winds were expected to hit Auckland, Northland, Coromandel Peninsula and the Bay of Plenty this afternoon, while some exposed parts could see gusts of up to 100km/h later this evening.

Thunderstorms are also forecast across Northland with a risk of localised downpours and very strong winds.

Tomorrow is expected to usher in the worst of the winter storm as it stalls over Canterbury and Otago bringing snow down to 400m. As well as snow parts of Canterbury are expecting more than a month's worth of rain in a day.

MetService said the heaviest falls were expected in Canterbury and eastern Otago, including Dunedin, where up to 160mm of rain was expected to fall tomorrow.

Forecasters warned the combination of heavy rain and strong would were expected to cause widespread travel disruption, flooding and slips and damage to trees, powerlines, unsecured roofs and structures.

Today's forecasts:

Auckland: Rain setting in by midday, heavy falls, northeasterly gales 17C
Hamilton: Rain setting in by midday, heavy falls, northeasterly gales 17C
Tauranga: Rain setting in by midday with possible downpours. Northeasterly winds strengthening. 18C
Wellington: Showers today, rain at night. Northerlies 14C
Christchurch: Cloud thickening, occasional rain from evening. Northerlies turning southeast. 15C
Dunedin: Morning rain, Southeasterly winds tonight. 12C