A weather eye on events in the sky

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By Mick Jensen

The MetService has three weather radars on the South Island and one of them is tucked away on a rise and in the middle of a paddock between Dorie and Rakaia.

Many Mid Cantabrians wouldn’t know it existed, but the radar provides very useful weather data and is one of only nine in the country.

The radar tower is 18m tall and recently received a paint job. It was changed from green, the colour of the nearby trees, to a lighter shade that blends with the sky and will also last better in the elements.

The radar was commissioned in February 1992 and was the third in the Meteorological Service’s (now MetService) programme.

The radar antenna inside the dome is 4.2m in diameter and records all forms of precipitation (rain, hail and snow).

Earlier this year, and when the weather was warmer, the radar beam “picked up high flying insects. They were seen not as a swarm, but each insect was seen as a big, fat raindrop.

The Rakaia radar “operates in two different modes, both visible on the MetService.com website.

In weather surveillance mode, it has a range of 300km, while in high resolution doppler mode, the range is 120km.

The radar performs a scan every seven and a half minutes and that scan appears on the website minutes afterwards.

The Rakaia radar’s uptime is very high, with a 99.5% averaged over the last six years.

The MetService will build a fourth South Island weather radar on the Otago coast at Hindon next year, a project expected to cost $2.8 million.

Other Mainland radars are also located at Invercargill and Hokitika.

The MetService intends upgrading the Rakaia radar in the next three years, using the same technology that will be installed in the new Hindon radar.