Active start to summer

GLOOM LINGERS: The wet and windy pattern continued throughout January with remnants from Cyclone June bearing down on the country.

The start to summer misfired somewhat before slowly settling into the normal pattern during mid to late January. The first weeks of December brought no major active weather systems but day-time heating and local converging winds allowed thunderstorms to develop during the warm summer afternoons.

When the day-time heating and convergence coincided with a passing trough the resulting thunderstorms were all more notable. Some even became severe bringing heavy downpours, medium sized hail and strong gusty winds.

Then, it all went pear shaped over the holidays as two stubborn lows lingered in place from Christmas until the end of the year.

A few places did manage some sunshine for Christmas Day, but in the days that followed in many places the raincoats were the chosen attire.

By the weekend the second, subtropical moisture rich low, moved in from the North Tasman Sea across the country. This low brought some widespread heavy rain and thunder from Northland down to Gisborne.

The rain was very intense on Sunday, December 29, with rainfall in excess of 25mm/hr across parts of the Coromandel. There was widespread flooding with many campgrounds inundated with flood water. Whitianga received 120mm of rain during the 24 hour period which is equivalent to the mean rainfall for the entire month.
More active spring like weather spread in for New Year's day with heavy rain and thunderstorms that affected the west coast of the South Island and a few spots further east.

Further active troughs that brought heavy rain and gales continued through the first week of January. Strong to severe gales affected many western and central parts of New Zealand with another notable active trough on January 3 & 4. Winds gusted over 140km/hr in the hills surrounding Wellington. On the same day over 300mm of rain fell in the ranges of Westland region and the afternoon high reached 28C in Gisborne in the warm northwesters.

Cyclone June
The third week of January brought more wet and windy weather this time it was from the remnants of cyclone June. The weakened but tropical moisture rich storm system brought a good dosing of rain as it pin-wheeled across the country. The ex-cyclone also brought strong to severe gales especially across northern and western parts of the North Island on the back side of the depression.

Outlook
The active westerly flow will continue to ease and anticyclones to our west will begin to move across the country with more regularity. There will still be some active troughs especially in the south and the tropics will also add another factor into the mix especially during more active phases. Favourable upper level steering winds at the time will determine if any of those tropical features make their way in a weakened form to New Zealand.

The greater variety of weather systems will help to bring us more fine days.