Cyclone Gita due to hit today

Severe weather warnings have been issued as cyclone Gita approaches New Zealand today.

Tropical cyclone Gita zig zagged through the tropics last week, first tracking east, then swinging in a u-turn to head west,causing damage in Samoa, Tonga and Fiji as well as New Caledonia on it’s way. It then swung in an arc south west then southward, then south eastward towards the middle of New Zealand.  While no longer tropical cyclone strength there are warnings it may cause major problems through heavy rain, strong winds and a storm surge (up to 7 metre swells).

CYCLONE GITA UPDATE (Metservice 2:41 am Tuesday 20 February):

Cyclone Gita is currently undergoing extra-tropical transition, and has been re-classified as ‘Former Cyclone Gita’. Although Gita is no longer a tropical cyclone, it’s still expected to significantly impact much of central New Zealand over the next 24 hours.

Heavy rain is already occurring from Taranaki southwards to the Sounds, and is expected to spread over Buller, Nelson and the remainder of Marlborough over the next few hours.

Strong winds are expected to develop early this afternoon into this evening for the entire country, with the potential for damaging wind gusts from Taranaki and Taihape south to Westland and Banks Peninsula, including Wellington.

Watches and warnings remain in effect for Strong Winds and Heavy Rain, available on metservice.com, along with your latest weather forecast.

So it looks like the top of the South Island is going to bear the brunt of Gita, in particular the Nelson and Buller areas, but with a much wider area affected.

Gita has transitioned from a tropical cyclone to a cyclone as it has headed south into the mid latitudes. Metservice blog: Tropical cyclones: extra-tropical transition

So, how does this extra-tropical transition take place? When a well-developed tropical cyclone reaches its peak in the heart of the tropics, it has an eye. The eye is often fairly cloud-free, nearly circular, and surrounded by a ring of very active thunderstorms. In the early and middle parts of their lives, tropical cyclones stand up quite vertically in the atmosphere, like large columns.

Besides encountering cooler seas, tropical cyclones heading towards New Zealand eventually come under the influence of the westerlies. The westerlies of the mid-latitudes increase in strength with height, a phenomenon known as vertical wind shear. This shear almost literally chops off the upper part of the tropical cyclone and sweeps it away, not unlike a woodcutter chopping off the upper part of a coconut tree to leave a section just above the ground (except it’s a much more gradual and subtle process). Along with the lower sea temperatures of the mid-latitudes, this destroys the positive feedback processes within the cyclone.

What remains is the former tropical cyclone’s low-level circulation, which may get carried off in the westerlies or become the focus of further development if conditions are right. Either way, tropical cyclones approaching the New Zealand area undergo drastic changes of structure and appearance as they undergo this extra-tropical transition.

Metservice Severe Weather Warning:


Heavy Rain Warning

Heavy rain may cause streams and rivers to rise rapidly. Surface flooding and slips are also possible and driving conditions may be hazardous.

Area: Nelson and Buller
Valid: 14 hours from 7:00am to 9:00pm Tuesday
Forecast: Expect 150 to 200mm of rain to accumulate in Nelson west of Motueka, and 90 to 150mm elsewhere. Peak intensities of 20 to 30mm/hr possible.

Area: Marlborough including the Kaikoura Coast
Valid: 15 hours from 7:00am to 10:00pm Tuesday
Forecast: Expect 150 to 200mm of rain to accumulate about higher ground, and 90 to 140mm elsewhere. Peak intensities of 20 to 30mm/hr possible.

Area: Wellington and Kapiti Coast
Valid: 15 hours from 1:00am to 4:00pm Tuesday
Forecast: Expect 75 to 100mm of rain to accumulate during the period. Peak intensities 20 to 30mm per hour during the morning. Further lighter rain is expected from late Tuesday afternoon to midnight Tuesday.

Area: Canterbury Plains (excluding Christchurch)and High Country, the ranges of Westland
Valid: 27 hours from 12:00pm Tuesday to 3:00pm Wednesday
Forecast: Expect 150 to 200mm of rain to accumulate during this period about Canterbury High Country, and 90 to 120mm elsewhere. Peak intensities of 20 to 30mm/hr possible about Canterbury High Country.

Strong Wind Warning

Strong wind gusts could damage trees, powerlines and unsecured structures. Driving may be hazardous, especially for high-sided vehicles and motorcycles.

Area: Taranaki, Taihape, Whanganui
Valid: 10 hours from 3:00pm Tuesday to 1:00am Wednesday
Forecast: Severe gale north to northwest winds gusting 120 km/h in exposed parts of North Taranaki, but damaging gusts of 140 km/h in exposed parts of South Taranaki, Whanganui and Taihape.

Area: Manawatu, Kapiti-Horowhenua, Wellington and Wairarapa including the Tararua District
Valid: 8 hours from 7:00pm Tuesday to 3:00am Wednesday
Forecast: Severe gale north to northwest winds gusting 120 km/h in exposed places, but 130 km/h in Wellington on Tuesday evening.

Area: Nelson and Buller
Valid: 8 hours from 2:00pm to 10:00pm Tuesday
Forecast: Severe gale east to northeast winds with damaging gusts of 130 to 140 km/h in exposed places.

Area: Marlborough including the Kaikoura Coast
Valid: 12 hours from 3:00pm Tuesday to 3:00am Wednesday
Forecast: Severe gale southeasterlies gusting 120 km/h or more in exposed places.

Area: Westland and the Canterbury High Country near the Alps
Valid: 13 hours from 12:00pm Tuesday to 1:00am Wednesday
Forecast: Severe gale southeast winds with damaging gusts of 150 km/h possible in exposed places.

Area: Canterbury from Banks Peninsula northwards
Valid: 8 hours from 7:00pm Tuesday to 3:00am Wednesday
Forecast: Severe south to southeast gales gusting 120 km/h in exposed places.

This warning will be updated by: 11:00am Tuesday 20-Feb-2018


That’s strong winds but they don’t seem out of the ordinary for gales. There is a lot of rain forecast in mid New Zealand.

RNZ: Country prepares for Cyclone Gita

The worst affected areas are likely to be Taranaki, the Kāpiti Coast, the Marlborough Sounds, Nelson, the West Coast, and the east coast as far down as Canterbury.

Grey District Mayor Tony Kokshoorn was expecting storm surges and more than 100mm of rain overnight – in an area already struggling to clean up damage from cyclone Fehi earlier this month.

Following a meeting this afternoon, the Ministry of Education directed all Buller/Grey district schools to close for two days.

Civil Defence has alerted 2000 campers on the West Coast with a special app with notifications.

Accommodation providers on the coast are also telling tourists about the cyclone.

In Marlborough, Civil Defence is asking campers, trampers and boaties to leave the area today if they can, or find themselves somewhere safe to hole up.

Heavy rain could cause slips, rapidly rising streams and rivers, and flooding, with State Highways 6, 1 and 63 potentially affected, said Marlborough Civil Defence spokesman Glyn Walters.

The Interislander ferry said sailing will be rough on Tuesday evening and Wednesday morning, but at this stage it isn’t expecting to cancel services.

The latest MetService forecasts showed the cyclone arriving a band from the west across the south of the North Island and the north of the South Island.

 

Cyclone Gita warning – “highly impactful” likely in NZ

Metservice Severe Weather Outlook

Cyclone Gita is expected to approach New Zealand from the northwest early next week.There remains uncertainty with regards to the speed and track of Gita, but the passage of this system across New Zealand on Tuesday and Wednesday is likely to bring a period of highly impactful severe weather.

There is high confidence of severe gales and heavy rain spreading across central and northern New Zealand on Tuesday and Wednesday.

In addition, winds associated with Gita are likely to cause large waves to affect some coastal places, and the expected storm surge allow run-up of waves in some low-lying coastal places, particularly at high tide.

map showing severe weather outlook

NZ Herald – Cyclone Gita: MetService warns ‘it’s best to prepare’

MetService is urging people to prepare for Cyclone Gita as it makes its way to New Zealand.

Risk areas are yet to be identified- they will be earmarked closer to Gita’s arrival – but MetService says the tropical cyclone is likely to bring with it “highly impactful severe weather”.

WeatherWatch has advised people to postpone any non essential outdoors activities on Tuesday and Wednesday, especially hikers and trampers.

People are asked to check their emergency kits are up to date with enough food, water, batteries and cellphone chargers.

Gutters should be cleared in preparation and pets should be provided for too.

NIWA meteorologist Chris Brandolino said it would be a fast-moving ex-tropical cyclone.

“New Zealand looks like it will get an impact, but the question remains over whether it will be more of a central North Island event, or is it going to be more of an upper South Island kind of event.

“The more reliable models are pegging the Kāpiti Coast up to the Taranaki region, east to southern Hawke’s Bay and down to the Wairarapa but that doesn’t exclude other areas”.

Cyclocane: Gita Tracker

NZ Herald: Everything you need to know about Cyclone Gita including how it might affect NZ

 

Cyclone Gita hits Tonga

Tonga was hit by Cyclone Gita overnight. It is too soon to get an appreciation of the amount of damage but winds, heavy rain and a storm surge are likely to have been very damaging, but it is too soon to tell how devastating it has been.

RNZ:  Cyclone Gita: Houses destroyed, church ‘completely gone’

Fiji’s MetService said the category four storm was very close to being upgraded to the highest category, five.

It had already washed out building and equipment of Tonga’s met office, and Fiji weather forecasters took over issuing warnings for the region from shortly before midnight.

The storm was expected to be upgraded to a category five in the early hours of the morning.

The US Joint Typhoon Warning Centre earlier said it was hitting maximum sustained winds estimated at 233km/h.

Well-built framed homes can be damaged in category four winds, and most trees will be either snapped or uprooted and electricity and water outages could last anywhere from several days to weeks after the storm.

The local radio station is also disabled.

Check out RNZ’s live coverage here

There are reports of very high winds in the capital Nuku’alofa.

The Fiji met service reported the cyclone was 30km south south east of Tongatapu at 11pm and moving west northwest about 30km an hour away from Tonga.

Authorities have switched off the electricity for about 75,000 residents who live on the island.

The Tongan Red Cross communications advisor Poli Kefu earlier said several houses had already been destroyed in Tonga.

This story will unfold over the next day or two in Tonga, as Gita heads westwards towards (but possibly to the south of ) Fiji and then in the direction of New Caledonia. At some stage it is expected to turn south and may have some impact on New Zealand eventually.