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Cyclone Gabrielle strengthening as it slowly passes Great Barrier Island (20+ maps)

> From the WeatherWatch archives

12:15am Tuesday NZDT — Cyclone Gabrielle’s movement has slowed to an absolute crawl near Great Barrier Island.

The longer the cyclone takes to move through, the higher the rainfall totals will go – and increased wind damage.

As we head towards sunrise the tracking of the centre of the storm will begin to gradually speed back up again as it shifts from a southerly track to a south-easterly track again. This will take it towards East Cape, arriving there likely mid-Tuesday afternoon, based on modelling on Monday night.

Gabrielle is expected to continue deepening (air pressure wise) until around dawn (5am – 7am roughly). This means severe weather is expanding and strengthening over much of the North Island as we go into Tuesday.

Heavy rain is lingering in Northland and Auckland this morning – pushing totals up. Severe gales are also going to continue on for many in these two regions (but in some locations they may ease back a little, as the winds tilt from southerly to south-south-westerly. These winds are likely to be pulled back in from the Tasman Sea as the storm slowly moves away from the top of the North Island over Tuesday meaning western areas in particular maybe quite exposed to damaging gusts and power outages.

That tracking will also mean severe gales are expanding southwards into the lower North Island and upper South Island, taking Gabrielle’s rain bands there too.

This is a serious ongoing event which will last at least another 24 to 48 hours across many regions of New Zealand.

Stay up to date with MetService warnings and WeatherWatch.co.nz. Also hourly weather data, totals and graphs at RuralWeather.co.nz.

The lower the air pressure the more powerful and severe the storm is. It makes the storm more unstable and will see wind and rain spread further out and intensify. The fact this intensification is going to occur as Gabrielle approaches the Auckland and Coromandel Peninsula regions makes it more problematic and complicated.

New Zealand’s mountains and ranges also play a big role. “In the United States when storms come off the Atlantic they don’t have to contend with large mountain ranges as much of southern and south eastern US is quite low down, making severe weather more evenly spread. But in NZ our mountains and ranges alter the weather, producing pockets of calm whilst other areas are made much more intense by the terrain. It adds another layer of complication to forecasts” says head forecaster Philip Duncan. “This is the reason why some have lost power and others may be wondering where the worst winds are”.

Gabrielle is a large storm, WeatherWatch.co.nz says it’s at least two to three times the size of New Zealand and is yet to properly arrive. That’s why across Monday night and Tuesday we’ll be seeing the peak of this storm moving through, with conditions easing around Thursday and Friday.

Latest tracking shows the centre of Gabrielle to move over, or very near, Great Barrier Island in the Auckland region and northern Coromandel Peninsula tonight and then drift over the Bay of Plenty (sea area, not land) towards East Cape. This placement may help Auckland reduce storm surge risks a little – but also means windier weather may linger for longer. However the S-SE wind flow is often kinder to Auckland city than a NE wind, thanks to the specific placement of Gabrielle so far. This is helping Auckland avoid having even worse winds.

Auckland gets a lot of attention due to the size of the population – and the recent severe weather – but many regions in the east will have wetter weather, with over 500mm possible if Gabrielle slows down. Stronger winds will also likely occur to the east of many of the main ranges of the North Island.

It’s fair to say that the worst is yet to come for many parts of NZ as Cyclone Gabrielle finally moves in tonight – and strengthens further with severe weather spreading down NZ and towards the upper South Island.

Comments

Before you add a new comment, take note this story was published on 13 Feb 2023.

Jaco Du Preez on 13/02/2023 12:05pm

Realy appreciate the fantastic work that you guys are doing. The frequent updates are very informative and provides a measure of comfort in knowing what to expect.

Felyne on 13/02/2023 9:47am

IABLAN25 is reading 967.83 on ruralweather, is that right (it’s currently 10:47pm)

WW Forecast Team on 13/02/2023 10:04am

Not sure sorry – a lot of those private ones aren’t perfect, it sounds a bit low (Auckland is 976hPa as 11pm)
– WW

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