North Island storm

We’ve only had a small amount of rain, a bit more breeze and a bit of cooling in the south, but there has been a major storm affecting much of the North Island and upper South Island.

Stuff:  Deadly storm causes travel chaos amid evacuations and widespread flooding

A woman has died after a tree fell on to a car in Rotorua, as a storm brings devastation and travel chaos to large parts of the country.

Niwa said 41mm of rain had fallen in Auckland since 9am on Thursday – more than the total amount of rain in November and December combined.

The wild weather prompted Air New Zealand to cancel or delay all regional flights. Flights in and out of Tauranga and Rotorua were also cancelled, with many more delayed.

The ASB Classic tennis tournament was a washout for a second day in Auckland, and the final won’t be played until Sunday.

The storm, which had entered into its second day, had caused widespread damage across much of the North Island and upper South Island.

Stuff: From drought scare to deluge despair: The science of the storm

After a period of calm, dry weather for much of the country, in which century old records for dryness were toppled, the furious storm from the north seemed to come out of the blue.

What may at first seem like atmospheric whiplash was actually a case of cause and effect – and may be a taste of things to come.

The sub-tropical low roaming down the country, which formed earlier in the week near Queensland in Australia, is the most significant storm to hit New Zealand in many months.

Part of the storm’s intensity, however, can be traced back much further, to the settled days of late November when much of the country was cloaked in sunshine and worrying about drought.

A weather pattern consistent with La Niña caused arm temperatures and widespread dryness, particularly in the south. It didn’t rain at all in Christchurch for more than 40 days, an effect which spread like a halo to much of Canterbury where rainfall totals for the month were in single digits. In Milford Sound, the wettest part of the country, it didn’t rain for 23 straight days.

Those warm, dry, and settled conditions contributed to an unusual phenomena: a marine heat wave, in which sea temperatures around New Zealand were about 2 degrees Celsius warmer than average.

Off the west coast, in the Tasman Sea, temperatures were as much as 6C above normal – at the time, it was the largest sea temperature anomaly in the world.

When weather conditions are settled – effectively meaning a lack of wind – there is no mechanism for deeper, colder water to come to the ocean’s surface, which keeps the seas warm, says Niwa scientist Chris Brandolino.

“Warm ocean temperatures release a lot of heat and a lot of energy into the atmosphere, and if you have a storm or a low pressure passing over that, it can provide the necessary energy to really ramp up the intensity of the storm”.

“In other words, if the same storm were to pass over waters that were cooler than average, as opposed to warmer than average, I’d be shocked if we got a similar result.”

That effect is a major reason why climate scientists say rising temperatures will increase the intensity of extreme weather events: warmer oceans can empower storms, potentially increasing rainfall amounts and wind speeds.

Stuff:  Living on the Edge: What climate change means for Taranaki

The climate change debate has hogged headlines recently but its influence on humanity is undeniable. In the first of a six-part series called Living on the Edge, reporter Deena Coster takes a deeper look at what it means for Taranaki.

The rough and rugged Taranaki coastline will be unrecognisable in 100 years’ time.

Houses once dotted along the coast will be lost, as coastal erosion and rising sea levels steal away the very land they rest on.

Creating a clear understanding of which areas of New Zealand are vulnerable to sea level changes is at the heart of a new $8m study.

For the next five years, the NZ SeaRise Programme will attempt to provide accurate estimates of the magnitude and rate of sea level rise for coastal regions to the end of this century and beyond.

Detailed maps will be drawn up from the data in order to show larger seaside settlements where its vulnerabilities lie.

One involved in the study is Professor Tim Naish, of the Antarctic Research Centre, based at Victoria University of Wellington.

He says regardless of what changes are implemented now, a 50cm sea rise by 2100 is unavoidable.

“That’s built in; we can’t avoid that.”

In Taranaki, Naish says rivers like the Waitara, Waiwhakaiho and Te Henui are going to rise, creating a flooding risk to low lying areas nearby.  The frequency of big storms hitting the region is also likely to increase.

Coastal erosion is another biggie.

Naish says adapting or doing something to protect itself is something local authorities are grappling with around the country.

Damage done to property and infrastructure through the effects of climate change, or budgeting to protect key assets, can represent a “big economic cost” to councils, but this needs to be balanced against the consequences of doing nothing, he says.

The social toll also can’t be ignored, including the potential relocation of communities away from at-risk areas in future years.

“That’s where it gets really difficult.”

 

Is it a storm up north?

Despite the efforts of media to talk it up into a dramatic story this week’s weather in the south of the South Island has been pretty average for July, with nothing out of the ordinary.

Weather forecasts and warnings were fairly accurate although there seems to have been less snow than predicted.

This does accurately show a light smattering of snow on a hill.

The worst of the weather is forecast to be hitting the lower North island today:

Kim Hill just said “the winter storm that battered the South Island yesterday” is a typical ignorant overstatement.

But it may reach storm level up north – over to Your NZ North Island reporters…

Cyclone Cook storms down New Zealand

The remnants of the tropical cyclone named Cook hit the Bay of Plenty yesterday afternoon and is still storming down New Zealand. It is expected to track down to the east of the South Island today.

The North of the North island including Auckland weren’t hit as badly as predicted but slips, damage and power outages are reported from other areas.

The extent of the damage will become apparent during today.

While there were warnings it may have been as bad a storm as Giselle that struck in 1968 when the Wahine sank in Wellington it seems to have not been as intense or destructive.

Stuff is covering it live: Trees down and roads blocked as Cyclone Cook arrives in New Zealand


WHAT YOU NEED TO KNOW ABOUT THE STORM:

  • The worst of ex-Cyclone Cook is over. It’s currently sitting south of the North Island, moving south and weakening. However, it may bring strong winds, heavy rain and possible flooding to eastern Marlborough and Kaikoura on Friday morning.
  • The storm is expected to sit east of Banks Peninsula about 9am on Good Friday before lying east of Oamaru about midday, and well east of Dunedin in the late afternoon.
  • Strong winds are expected in Wellington early on Friday morning, and around Kaikoura and Banks Peninsula later in the morning.
  • The storm has caused flooding and slips on the North Island’s east coast, with numerous roads closed.
  • The Motueka Valley Highway has been blocked by a slip near Stanley Brook.
  • Power is out in many North Island areas. Whakatane, Te Puke, Opotiki and Waimana have been hit by blackouts, along with Napier and Hastings. More than 2000 customers have lost power in the Hawke’s Bay and Gisborne regions.
  • Air New Zealand has suspended operations from Tauranga Airport.
  • States of emergency are in place in Thames-Coromandel and the Bay of Plenty.
  • Read more: What can each region expect? 
  • In pictures: Heavy rain hits New Zealand

What happened overnight?

“The worst of it was last evening when it came through Bay of Plenty. At midnight, the low was passing over southern Hawke’s Bay and over northern Wairarapa. The strongest winds around Bay of Plenty were last evening and the strongest winds around Gisborne and Hawke’s Bay were late evening up to about midnight.

After midnight, the strongest winds have mostly been about Wairarapa and they were gusting up around 100kmh, mostly about the east coast of Wairarapa – Castlepoint and those sorts of areas.”

– MetService severe weather forecaster John Crouch

RNZ: The lowdown on tropical cyclones

As Cyclone Cook passes over New Zealand’s east coast, cutting power and closing roads, Alison Ballance looks at the science of tropical cyclones.

Stuff:

Have we been lucky? 

“We have in a way. It tracked a little further east than some of the original predictions, which means that Auckland in particular didn’t get affected by it, and it probably wasn’t as deep as some of the initial predictions as well.” – MetService severe weather forecaster John Crouch

Some people seem to think that weather forecasts and warnings are promises. They are just (usually fairly accurate) predictions of probabilities. Things often turn out to be not as bad or a bit worse than estimated.

Over-warning is better than under-warning.