Autumnal gales and rain on the way

May 4, 2015

A ridge of high pressure that brought fine weather and light winds to much of New Zealand over the weekend is now departing slowly to our east. This ushers in a period of northwesterlies, which will bring bursts of heavy rain and gales to parts of the country this week.

An active trough embedded in this northwest flow moves onto the lower South Island late Tuesday, bringing rain to the West Coast. “Before it completely loses its grip, the ridge dishes out mostly settled weather to the remainder of the country today and Tuesday, although cloud and wind increase in the west of the North Island,” commented MetService Meteorologist Peter Little.

On Wednesday rain becomes heavy on the West Coast as the trough moves slowly northwards, with significant spillover expected into the headwaters of the Canterbury and Otago lakes and rivers, along with thunderstorms. In addition, the northwest flow strengthens ahead of the trough with severe gales possible about exposed eastern parts of the South Island. Severe Weather Warnings and Watches have been issued and the details can be found here: http://metservice.com/warnings/home

The trough moves onto the North Island on Thursday, with a wet and windy day expected in many centres. “The front remains active as it crosses the North Island, so it’s likely that more areas will be added to the Warnings and Watches in the coming days,” Little went on to say. “Despite the rain and wind it is looking like a warm week across the country, especially in the east of the North Island, where northwesterlies could push the mercury into the mid-twenties on Wednesday and Thursday afternoons,” added Little. Although the heavy rain eases over northern and western parts of the South Island behind this trough, the northwest flow prevails and a second front brings another burst of heavy rain to Fiordland and South Westland on Thursday. It’s not until Friday that there’s a change to showery westerlies behind these troughs.

Looking further ahead, at this stage we see northwesterlies returning over the weekend for Mothers’ Day on Sunday. Little went on to say, “This means it should be mostly fine, dry and mild in the east of both islands. Increasing cloud and showers are expected in the west of the North Island. You may want to plan to do something indoors with Mum if you live in the west and far south of the South Island, as rain is forecast there”.

Keep up to date with the latest forecasts and any watches/warnings at metservice.com or on mobile devices at m.metservice.com. You can also follow our updates on MetService TV, at MetService New Zealand on Facebook@metservice on Twitter and at blog.metservice.com.

For further information please contact:
Peter Little Meteorologist (04)4700 754


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MetService issues Warnings, Watches and Outlooks for severe weather over New Zealand.
Warnings are about taking action:
* When severe weather is imminent or is occurring
* Issued only when required
* Recommendation: ACT
Watches are about being alert:
* When severe weather is possible, but not sufficiently imminent or certain for a Warning to be issued
* Issued only when required
* Recommendation: BE READY
Outlooks are about looking ahead:
* To provide advance information on possible future Watches and/or Warnings
* Issued routinely once or twice a day
* Recommendation: PLAN
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