Predictwind- Tracking Cyclone Lusi Update 3- 60kts in Hauraki Gulf

by Richard Gladwell, Sail-World.com/nz on 15 Mar 2014
Tropical Cyclone Lusi hit New Zealand, on late Friday night bringing strong winds and rain to the top half of the North Island.

Winds gusting to 60kts have been recorded at several points on the eastern coast including Cape Reinga, Channel Island and Tiritiri Island in the Hauraki Gulf.

Auckland appears to have been spared the worst of the onslaught, with Rangitoto Island providing some protection.

Sail-World started tracking the storm at 2200hrs on Thursday night - see two earlier stories and maps. This latest update is at 1000hrs on Saturday. The times of the shots of the storm can be read alongside each image.

A disturbing feature of the latest predictions is that the middle of the South Island and already flooded Christchurch, will be hit with heavy rains, when the city had been previously expected to avoid the heavy rainfall.

Rain from the cyclone is expected to hit about 4.00am on Sunday.

By Monday morning the low pressure area will have disappeared off the bottom of the South island and is expected to dissipate.

The first three Isobar images show the progress and expected track of the low pressure area from the Pacific at 1000hrs on Saturday night, and again 12 hours later on Saturday night, and some from Sunday.

Predictwind produces two weather predictions based on two independent feeds and then applies various adjustments to take account of a variety of factors including land mass and topography. For a fuller explanation of how PredictWind enhances its feeds to provide a detailed local forecast click here

As can be seen above, Cyclone Lusi has stayed intact passing over the top of the North Island and will spin out into the Tasman Sea before coming back over the middle of the South Island. Predictwind does take account of topographical features when making its forecasts - which indicates the rainfall in the South Island will be as expected and will have taken the Southern Alps into consideration.

In this Forecast Table from Predictwind.com we are just showing the Forecast at Bean Rock, which indicates the winds staying strong into Sunday.

Winds did hit the predicted strengths in gusts and at the correct time 0700-0900hrs on Saturday morning. They are how expected to ease a little.

In both the feeds used by Predictwind, the prognoses are very similar, indicating that there is a high degree of confidence between the models as to the predicted outcomes.

The third graphic shows the real time weather observation points around the North Island, these points are used to track the actual wind strength and direction, as the cyclone moves south and can be compared to the history of wind strength and direction from more northern points such as Cape Reinga and the Hauraki Gulf.

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The fourth set of graphics shows the advance of the rain, which will be heavy but is not expect to last that long, but will be replaced with strong winds. The rain has largely passed in Auckland, but will remain in the Coromandel and move into the eastern Bay of Plenty.

The point of concern is now with Christchurch and catchment areas to the west on the slopes of the Southern Alps.

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Stay tuned for further updates

Sail-World will update these forecasts and charts as the storm nears and passes over New Zealand reflecting any updates and changes in Predictwind's weather feeds, and the actual data being recorded.

Developed by former Olympian, Jon Bilger (470, 1992), PredictWind application was used by the Swiss team Alinghi to win the 2003 and 2007 America's Cups, and has become the leading wind system used by racing and recreational sailors around the world. It is available on a subscription basis and also with a free forecast option.

A mobile app for Android and iPhone is available and PredictWind is probably the most used app on the Sail-World iPhone.

You can check the weather anywhere in the world, and get a five day forecast, plus a variety of other features and functions of PredictWind. The app is synchronised with your PC, so that your latest set of locations are always available without resetting each time you change a device.