Sunday, 18 February 2018

A reformed cyclone Gita set to hit New Zealand on Tuesday

Cyclone Gita - Latest tracking starts to firm up a little more



17 February, 2018

UPDATED 11:45pm Saturday --- Cyclone Gita still remains a Severe Category 3 tropical storm as it moves into the northern Tasman Sea, although it is likely to drop to a Category 2 cyclone overnight.
Central air pressure has actually dropped a little today, from 973hPa this morning to 970hPa this evening. This is still well up from when it dropped to 927hPa as a Category 5 storm earlier in the week, but remains very deep and stormy for a low pressure system in the Tasman Sea.


Gita still retains an eye, although it has weakened and fallen apart a bit today. This is the image taken this evening as sun was setting over it.

Gita remains an intense and serious storm with a huge amount of wind and rain around it - and a lot of tropical air. New Zealand is directly in the path of Cyclone Gita and today the models started to agree on where it might make landfall, but we still need more time to confirm things.
GFS (American modelling) has been picking a South Island landfall for days, while ECMWF (European) has been picking the western side of the North Island from Wellington and Taranaki to Waikato. Today both of these trusted global sources have gone with the upper north west corner of the South Island. Of course this isn't yet locked in and with the storm still at least three days away this could definitely still change. However it does highlight that both main islands of New Zealand are at risk from flooding and wind damage. In the coming days we expect this to still shift around a bit northwards and southwards as it fine tunes the data.
Today Metservice significantly shifted their Severe Weather Outlook, removing the more North Island focus they had on Friday. MetService now says Gita will come in further south impacting more central areas which affects the upper South Island. This now aligns with what WeatherWatch.co.nz has been saying for the past two days, that a more central hit looks likely - this should help reduce confusion from some who were asking why we had quite different forecasts. Reliable modelling suggests landfall will be in the upper north west side of the South Island - we'll be more confident about locking this in by Sunday evening or Monday morning at the latest. 
Tracking from the Joint Typhoon Warning Center (US Government) says the gales will be expanding as it reaches New Zealand with their map showing gales are possible from as far south as Dunedin to as far north as Taranaki even Waitomo and Central Plateau maybe even Auckland. We expect a further update from them this evening.
Where the low makes landfall will help forecasters work out where the severe weather will most likely be. We need to lock in landfall before we can lock in precise severe weather risks and regions affected.
Computer models today say Cyclone Gita will have Category 2 strength when it arrives in New Zealand which means winds will be sustained at the centre between 89 and 117km/h. It may weaken quite fast when it hits the South Island's Southern Alps.
Gita has started the southerly turn to New Zealand which will take all weekend to stop the westwards movement. It's now tracking SW. For the past few days it's been tracking westwards. As of 8pm Saturday Gita was located 1550kms NW of Auckland, New Zealand.
There remains a lot of uncertainty about where the severe weather will be but all this past week guidance has suggested the upper South Island could experience very heavy rain. Damaging winds could extend for hundreds of kilometres from the centre of Gita. Because of this central tracking through New Zealand it means there could be issues in both islands. Travel delays are also likely, from motorists to air travellers to those crossing Cook Strait. Expect cancellations of some services early to mid next week if Gita holds on to the strength it has.
The storm is expected to bring waves of 12 metres and higher near the centre which could lead to significant coastal damage and flooding where the centre of Gita comes in.
Due to so much uncertainty with the models it will most likely be until Monday before exact location of landfall is worked out. Certainly central New Zealand (upper half of the South Island and lower half of the North Island) appears to be at the greatest risk based on the past few days of various models - but this could still shift further north or south. We'll keep you posted on what the models are saying in the days ahead but all New Zealanders need to be watching this closely.
Both GFS and ECMWF models suggest Cyclone Gita will arrive on Tuesday afternoon and overnight into Wednesday morning. What happens at that point is still not locked in either. It's becomes a much more complicated low by the time it reaches New Zealand which is why there is still uncertainty.






  

Hot Sunday for eastern NZ


The mercury will climb into the 30s today in the east of New Zealand with Hawke's Bay likely to be one of the hottest regions in the country with highs in the low 30s. Gisborne, Marlborough and Canterbury may all reach 30 degrees also.
Northern New Zealand will also have increasing humidity partially caused by Cyclone Gita which is well out at sea but will help make for higher 'feels like' temperatures. Overnight lows in the north will be above 20 degrees tonight too.
The Central North Island and Waikato are likely to climb into the late 20s with cloudy areas and some showers developing.
One of the coolest places today will likely be Queenstown with a high in the late teens or 20 degrees. 
Image: 4pm Temperature map (click to see temperatures across the week) / Weathermap.co.nz


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