Last blast before warmer weather

January 24, 2017

The contrast between north and south has been unusually pronounced this summer, with successive fronts lashing the south, and drought conditions in the north.  Cooler conditions have prevailed, with much of New Zealand 1 to 2 degrees colder than normal for January. This evening another major weather system affects the country, bringing severe wind and rain to central and southern New Zealand through Wednesday, before the weather stabilises and temperatures begin to return to normal.

Since the start of December, New Zealand’s weather has been driven by high pressure to the north and transiting low pressures to the south of the country.  In the last week, two deep low pressure systems have made a bee-line for New Zealand, spreading severe wind and rain further north than the previous southern systems.  Another deep low is expected to bring severe weather tonight, but apart from some heavy rain in the Tararua ranges and gales in Wellington and Wairarapa, the North Island is spared the worst of the weather again.  In contrast, a brace of Watches and Warnings have been issued for the South Island, where 70 to 110mm of rain is expected for Fiordland and southern Westland, and gusts of 120km/h or greater are anticipated in the east from Southland to Marlborough, as well as Wellington and Wairarapa.

“This weather system marks a tipping point in our summer”, said meteorologist Tom Adams, “after which temperatures increase. Next week sees some real warmth for the eastern North Island, and closer to average temperatures elsewhere in the North Island.  High pressures that have loitered to the north of the country descend further south, calming winds and reducing the impact of subsequent weather features.  Although the end of the week will see quite a bit of cloud, and on and off rain showers in the south, the risk of severe weather is lessened”.

2017-01-24

This image shows modelled daily rainfall accumulations for the next six days. Data UK Met Office.

Despite high pressure taking charge the odd front can still sneak through, and on Sunday the West Coast may see another dose of rain. But the front will weaken as it moves north under the high, so signs are looking promising for both the Auckland and Nelson Anniversary weekends, and Wellington’s Rugby Sevens event.

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

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