The Week That Was: The Low Vs. The Front

June 25, 2017

This Wednesday gone marked the winter solstice – that is, the shortest day of the year, or what most consider mid-winter. But due to the moderating effect of the ocean surrounding our small narrow islands the coldest weeks are likely still ahead of us. A taste of that is set to hit the South Island tonight with severe frosts forecast for some places, especially inland.

“The start of last week began settled, with light winds and clear skies making for good conditions to get outside and up on the slopes. However, late Wednesday a ridge of high pressure, previously holding-off a low to the northwest and a cold front to the south, moved east, off the country allowing the two weather features to combine over New Zealand” explained MetService Meteorologist April Clark.

“Moist, rain-making easterlies ahead of the low combined with colder, drier surface temperatures behind the cold front creating ideal conditions for snow about the central South Island ski fields on Thursday and Friday” said Clark.

The cold front was unable to muscle in over the more dominant low in the north – so warmer temperatures but rainy conditions persisted over the North Island through to Friday, heavy at times from Gisborne to Northland. As the low slowly moved off to the east late Friday winds turned strong southwest, gusting 131km/hr at Cape Reinga, and ushered in showery conditions for the entire country by Saturday. Though a few showers did fall on Eden Park during the All Blacks versus British and Irish Lions match Saturday evening, New Zealand fans certainly weren’t dampened.

The showery southwesterlies are forecast to ease today, and clear to fine for most of the South Island, with only the east coast of the North Island hanging onto significant showers this evening.

This image shows 24 hour rainfall accumulations from 7am Thursday to 7am Friday – calculated by combining radar and rain gauge data. The blank areas are those with insufficient radar coverage, due to distance, hills etc.

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