31 December 2012

A Big Northwest Storm

After an absence of several weeks, the westerlies have become established once again over New Zealand. A particularly strong and moist northwest flow is expected to affect southern and central parts of the country from late Monday through to Wednesday or early Thursday.

"Over the next few days, rainfall totals on the South Island West Coast and over the Southern Alps may approach their one- and two-day records," commented MetService Chief Forecaster Peter Kreft.

"By late Wednesday, MetService expects that two-day rainfalls in the catchments of the Westland rivers may be as high as 500 to 600 mm," Kreft went on to say. "Further, rainfalls in the headwaters of the Canterbury and Otago lakes and rivers may be in the region of 100 to 200 mm by then, which might make this an extreme event."

Very heavy rain on the South Island West Coast is often accompanied by strong warm winds east of the Alps. Northwest gales - or stronger - are expected in eastern areas from Southland through to Wairarapa, and in Wellington, from later Monday through New Year's Day and into Wednesday. "Around central New Zealand on Wednesday, the northwesterlies are likely to be particularly strong," Kreft went on to say.

"The warm weather and the time of year probably mean that there are a lot of people camping near lakes and rivers in Canterbury and Otago," said Kreft. "It's important that they are aware these lakes and rivers could rise rapidly, even if it's not raining at their camp site. And it's likely to be pretty windy down some valleys."

This week, it will be important to keep up-to-date with the latest MetService Severe Weather Watches and Warnings. Stay in touch with the latest at metservice.com or on mobile devices at m.metservice.com. You can also follow our updates on MetService TV, @metservice on Twitter.

ENDS

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