Re: Ex-Tropical Cyclone Gita impacts NZ Feb 18th-21st

[Bradley]

Looking at the latest SST anomalies in the Tasman Gita could really maintain it's intensity as it heads into the middle part of New Zealand, could be potentially stronger then it otherwise would have been...

cdas-sflux_ssta_swpac_1.png

[David]

EC now has it crossing near Auckland on the 20th, latest GFS has it making landfall in Taranaki 2 days later on the 22nd, with an intense core still intact...

[David]

Actually is that model "Global US Standard" the same thing as GFS?

Edit - seems to be from what I can determine.

[Cyclone Tracy]

EC now timing the polar injected nuclear scenario for Monday to Wednesday on the 1402 00z run

[Blowy]

Nuclear scenario indeed, would be great for the wind turbines... if they withstand, Yikes!

[jamie]

Wow that’s the “perfect storm” isn’t it?

[TonyT]

Wow that’s the “perfect storm” isn’t it?

Depends where you live. It could be the ultimate nightmare.

[Cherie]

Enthusiastic observer only here ... what does polar injected nuclear scenario mean in layman’s terms?
Those maps looks intense.

[spwill]

ECMWF is pointing to Tuesday 20th as the major day with this system.

[jamie]

Wow that’s the “perfect storm” isn’t it?

Depends where you live. It could be the ultimate nightmare.

Referring to the setup in the perfect storm movie.

[David]

ECMWF is pointing to Tuesday 20th as the major day with this system.

ECMWF surface wind gusts forecast for 1pm on the 20th

[TonyT]

Enthusiastic observer only here ... what does polar injected nuclear scenario mean in layman’s terms?
Those maps looks intense.

"nuclear scenario" is Mr Tracy's non-technical-but-apt term for the forecast combining of the cold polar air in the trough arriving from the south, with the humid sub-tropical air carried onto NZ by the ex-cyclone. When warm and cold air mix, especially when they are markedly colder and warmer than each other, and high in humidity, then low pressure systems can deepen rapidly, release substantial amounts of energy, and therefore bring stronger winds and heavier rain than they might otherwise do. "Polar injected" refers to the inflow of air from well south of NZ into the ex-cyclone's circulation.

[Cherie]

Thank you ^^
Polar air and sub-tropical air coming together - is that what happened with Cyclone Giselle?

[Razor]

Gee the next couple of days projections will be fascinating on all this. Could be squeaky bum time next week for some of us, looks riskier than Fehi did

[TonyT]

Thank you ^^
Polar air and sub-tropical air coming together - is that what happened with Cyclone Giselle?

It happens more often than you might think, but not usually over New Zealand.

[Tornado Tim]

Gosh, yes whats coming out the ECMWF Prognostics has a "Perfect" scenario to it.
All sectors of the low have significant divergence in the current prognostic, due to upper jet wrapping around the low but banking around the LLCC, which is quite rare.
974 to 958 hpa deepening within 24 hours in the latest EC 12z Run.
Will certainly need to keep an eye on this, especially if prognostics stay similar over the next few days!

[NZstorm]

Looking like the centre of Gita will make landfall in the Waikato region and the heavy precip south of there.

[David]

Looking like the centre of Gita will make landfall in the Waikato region and the heavy precip south of there.

Why does the rain seems to be concentrated on the southern side? It's interesting that with quite a close pass to Auckland the modeled rainfall is quite low.

[David]

GFS pulling it further south, showing landfall near Westport now. EC sticking to Waikato landfall.

[Bradley]

GFS always seems to exaggerate the surface pressure of these systems but still this could get very destructive for places like Westport, Greymouth, Kaikoura, Blenheim and even Christchurch if this current forecast track plays out...

[Razor]

Looks monstrous in the last few runs. Places like Granity will be bloody worried

[Bradley]

Looks monstrous in the last few runs. Places like Granity will be bloody worried

Just checked out Granity on Google Maps and some of those houses are so close to the shoreline it's just ridiculous, if this plays out then there is going to be a number of houses washed away

[Richard]

Looks monstrous in the last few runs. Places like Granity will be bloody worried

Most likely be easterly winds for them instead of the northerly from the last ex-cyclone. Having Gita cross the North Island will mean us on the SI east coast wont have to worry and the wind, ive never known of any damaging easterly quarter winds.

[NZstorm]

Latest 00Z modelling is for a landfall about Westport.

That means Auckland would experience minimal impacts.

[Chris Raine]

Well the CDEM and Health planning system for the West Coast have kicked into life today based on the GFS modelling . Metservice still feels the landfall will be in the North Island and GFS is wrong and prefer the European model. The 5 day Metservice model shows a West Coast impact as well.It all depends where the south east turn of the cyclone occurs . As we have a weekend coming up it is timely to plan this week and have the planning processes relatively complete the day prior to the storm itself across the various response agencies .Yes we are aware of the storm surge for Buller .At least we wont have king tides this time if the centre does in fact cross the Buller region