Downpour sets record
The torrential rain that caused chaos last week has set a national rainfall record, meteorologists say.
The 103 millimetres of rain recorded between 4am and 5am at Maungatapere, near Whangārei, on Monday last week set a national hourly rainfall record for a low elevation station.
The previous record was 100.6mm and was recorded 56 years ago in Whenuapai, Auckland.
National Institute of Water and Atmospheric Research (Niwa) principal scientist Chris Brandolino said the hourly rainfall rankings were calculated from top-of-hour to top-of-hour.
‘‘The maximum 60-minute total at Maungatapere on Monday morning was even higher at 123.2mm from 3.30am to 4.30am.’’
Brandolino warned ‘‘a warming planet’’ meant these type of extreme events could become the norm.
‘‘We expect to see more extreme weather events like this ... it’s likely such events will become even more common and more extreme,’’ he said.
Brandolino explained the downpour was not the ‘‘highestever hourly rainfall, but highest for a low elevation station’’.
’’That highest-ever record of 134mm in an hour is still held by the Cropp at Waterfall station near Hokitika, recorded on 8 January 2004,’’ he said.
As well as the extreme amounts of rain, around 3000 lightning strikes were recorded in Northland.
Brandolino said the thunderstorms, which were created by a low pressure system from the Tasman Sea, increased the rate of rainfall.
‘‘Ongoing marine heatwave conditions around New Zealand may have also contributed to the heavy rainfall,’’ Brandolino said.
Unfortunately, the heavy rain did not reach the Far North, where two fires have been burning since December.
The largest and most complex of these fires, at Waiharara, has been burning since December 18 and has burnt through nearly 2800 hectares of mostly wetland scrub in Kaimaumau.
A second fire, at Karikari Peninsula, also continues to burn in peat after starting on January 31 and burning 70ha of land.
Wipari Henwood, Fire and Emergency NZ Far North area manager, said neither Waiharara nor Karikari got a lot of rain because of their geography.
‘‘There’s no great land masses surrounding them, and the weather just blows straight over the top,’’ he said.
‘‘There was rain up there, but nothing of significance.’’
‘‘We expect to see more extreme weather events like this . . . it’s likely such events will become even more common and more extreme.’’
Chris Brandolino
Niwa principal scientist