A week of unsettled weather ahead

August 14, 2017

We’re looking at a week of unsettled weather with a series of fronts moving through, bringing a mixture of rain, thunderstorms, snow and strong winds  to many regions. There’s a little bit of a breather on Tuesday afternoon for much of the North Island and some of the South Island, which may give the washing a window of opportunity to dry out.

“An unstable northwest flow affects the North Island and upper South Island today, bringing heavy showers with thunderstorms,” explained MetService Meteorologist Ciaran Doolin. “The main risk of thunderstorms is for the  western North Island from Raglan to Hawera, especially from this evening.  These thunderstorms will be accompanied by mostly small hail, but the hail  may be larger (5-15 mm) from Raglan to Hawera,” added Doolin.

Meanwhile, a low pressure system east of Banks Peninsula brings heavy rain to Canterbury; a Severe Weather Warning is in place for this through until Monday night. Snow is forecast above 300 metres in Canterbury, and there is a Warning in force for heavy snow above 500 metres.

“People in the Canterbury area, especially trampers, are advised to look out for rapidly-rising rivers and streams, and localised flooding and slips,  ” said Doolin. “Heavy snow on the hills is likely to cause disruption to  transport and could place stress on livestock,” he added.

Through Tuesday and Wednesday, a trough of low pressure moves up the country and is followed by an active front which approaches the West Coast from the Tasman Sea on Wednesday. This front will be preceded by strong or gale northerlies and makes its way up the country on Thursday, bringing heavy, thundery rain to western areas and scattered falls further east. The northerlies are expected to bump up the temperatures in eastern areas, with Christchurch forecast to reach 18 degrees on Thursday.

“Heavy rain, thunderstorms and strong winds are expected to affect a number of areas between brief settled periods, so be sure to keep up to date with  the latest forecasts and any Severe Weather Warnings or Watches that are  issued,” Doolin said.

Official Severe Weather Watches and Warnings are reviewed and re-issued by MetService at least every twelve hours, and more often if necessary. To get the most up to date information on severe weather around the country, or any other forecasts, see 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  and @MetServiceWARN on Twitter and at blog.metservice.com


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. They are 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. They are issued only when required.
Recommendation: BE READY 

Outlooks are about looking ahead, providing advance information on possible future Watches and/or Warnings. They are issued routinely once or twice a day.
Recommendation: PLAN 

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