Thursday, 8 March 2018

Cyclone Hola could reach category 5

Just as the Atlantic is being hit by storm after storm the Pacific region and New Zealand is being battered.

Cyclone Hola: Could reach Category 5, winds of 300km/h, NZ in sights
Tropical Cyclone Hola has rapidly intensified to a Category 4 and could reach Category 5 tomorrow, with winds up to 300km/h as it batters Vanuatu, then heads for New Zealand.

The forecast track of Tropical Cyclone Hola issued by RSMC Nadi Tropical Cyclone Warning Centre around  8.45am Thursday. ...

8 March, 2018

The Fiji MetService upgraded the cyclone to Category 4 this morning, warning of sustained winds of 170km/h. Wind speed is expected to reach 200km/h today.

Vanuatu's Meteorology and Geo-hazards Department said this morning hurricane-force winds gusting to 185km/h were expected to hit Malekula and the Shepherds group tonight and in the next 12 to 24 hours. Damaging gale-force winds continue to affect the island of Ambrym in the Malampa Province.

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Minor to moderate damage to trees and structures in Central Pentecost.

Images courtesy of Andrew Gray.

Three forecasting models for Tropical Cyclone Hola predict the storm is likely to hit New Zealand's North Island early next week

Fiji Metservice's latest track map shows Tropical Cyclone Hola moving southwest towards New Caledonia before turning southeast in the general direction of New Zealand. Image/Fiji Metservice

Two models, from the UK Met Office, show Hola could hit the Bay of Plenty on Monday. It would be the third cyclone this season to affect New Zealand.

The third model, from the European Centre for Medium-Range Weather Forecasts, predicts it could make landfall about 6pm on Monday.

MetService New Zealand lead meteorologist Mark Todd said computer models were still struggling to give an accurate track but it was looking increasingly likely the storm would affect New Zealand.

The latest map from Fiji Metservice forecasts Tropical Cyclone Gita reaching Category 5 - the highest level - tomorrow. Image/Fiji Metservice

Hola has been moving slowly over Vanuatu during the past 24 hours, and reports say gale-force winds are collapsing some houses.

The roof of a classroom was blown off and some houses collapsed on Ambrym as the cyclone arrived, Radio New Zealand reported.

Todd said it was west of Vanuatu this morning, and moving slowly further west.

"We expect over the next day it should start to recurve to the south/southeast, in the general direction of New Zealand.

"If we are lucky it will pass just to the north of us. If we are unlucky, it could be a direct hit into the North Island.

"By then it will become an extra-tropical system, as always happens, but if it does make a direct hit there will be heavy rain and high winds."

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Vanuatu Red Cross is using social media to warn people to be prepared for which has just hit the northern islands. Volunteers are on standby. 

A "cut-off low" west of New Zealand has been wreaking havoc as it moves slowly over the North Island.

"We have a deep low in the upper atmosphere and a deep low at the surface generating all the rain and wind," Todd said.

And here's a great explainer on the structure of a tropical cyclone ^TA

Heavy rain and thunderstorms rocked much of the island last night when up to 200mm falling in places.

Wairarapa, Tararua and Hawke's Bay south of Hastings have a severe rain warning in place through to 9pm.

Heavy rain warnings remain in place for Taranaki through to 1pm.

"The heaviest falls were in the central areas, from Hawke's Bay and the Wairarapa through the central high country to Taranaki," Todd said.

More than 200mm was recorded on Mt Taranaki, and 129mm in nearby Stratford during the past 24 hours.

On the East Coast 90mm fell at Castlepoint in the Wairarapa and 83mm in Taumarunui.

The lower North Island including Wellington has been experiencing gale-force winds.

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Where are the strongest winds around a tropical cyclone? This analogy of a knife may help! Strongest winds where rotation adds to the system velocity. If When is travelling SE, strongest winds will be to NE. ^TA

"These are not expected to ease off," Todd said.

"There will be a gradual trend off, as the weather system moves very slowly.

"There is a risk of more widespread thunderstorms today, mainly in the central and upper North Island, even some hail."

Temperatures today would be much the same as yesterday, and the South Island is "the place to be", Todd said.

"There is a somewhat cooler air mass over the South Island, but it is going to be sunny, with very little rain."

Cyclone Hola: What NZ needs to know

There's a "significant probability" the remnants of Tropical Cyclone Hola will sweep over New Zealand on Monday - the third major storm to hit the country this year.

The forecast track of Tropical Cyclone Hola issued by RSMC Nadi Tropical Cyclone Warning Centre around  8.45am Thursday. ...
RSMC Nadi Tropical Cyclone Warning Centre
The forecast track of Tropical Cyclone Hola issued by RSMC Nadi Tropical Cyclone Warning Centre around 8.45am Thursday. Times are UTC which is 13 hours behind NZ daylight time.

8 March, 2018

So what do we need to know?

Hola intensified to category 4 strength early on Thursday, after crossing over Vanuatu, and was moving west southwest.
It was intensifying and, after changing direction, was expected to pass between Vanuatu and New Caledonia on Friday. It was possible it could grow to a category 5 cyclone, MetService said.

Where will it hit?

Latest forecast tracks indicated Hola would start tracking to the southeast on Friday. The final track would be highly dependent on where and when it "recurved", but it was expected to pass near or over the top of the North Island.
It could catch Northland, Auckland, Bay of Plenty and Gisborne in its wake.

How powerful will it be?

That is not known yet, as some forecasts say it will gain strength in the coming days. But Metservice said it would bring a short spell of wind, rain and larger swell, with possible severe weather in places. On Thursday the storm had sustained winds of 165kmh and gusts of 230kmh.

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