Baking, soaking in season of woe
Extremes of wet and dry make a tale of two summers
The big wet and the bone-dry: It’s been a tale of two summers for people on either side of the country. While the eastern region sweltered in one of the most rain-deprived Januarys in more than a century, some western areas were drenched with more than double the usual rainfall, leaving farmers with water-logged pastures.
Climate scientists say the big contrast is a typical southwesterly summer regime, only much more extreme.
National Institute of Water and Atmosphere (Niwa) meteorologist Ben Noll said Gisborne was on track to chalk up its driest month since 1905, and Napier to record its thirddriest January since 1870.
Colour-coded Niwa soil moisture maps showed how severe the picture was: Eastern swathes of the North Island, stretching from the East Cape to southern Hawkes Bay, remain in the red, with water deficits of 130mm.
Conditions in pockets of Wairarapa, Marlborough and northern Canterbury were similarly dry, while other eastern areas north of Canterbury showed deficits of between 90mm and 110mm.
Fire danger across eastern regions of both islands ranged from high to extreme.
But Noll said it had been the opposite story for many western areas in the past 30 days.
Large sections of the South Island had received between 120 and 160 per cent of normal rainfall and for some places in Taranaki and the eastern lower North Island, January delivered one-and-a-half times the usual amount.
“It’s all been totally driven by the wind direction, which has primarily been from the southwest,” Noll said. “We’ve now got some incredibly dry spots on the east and in the north of the North Island. Any rain would be beneficial there, but we really need a good couple of soakings.”
In Northland, farmers were discussing the possibility of a drought committee, while East Coast farmers were getting through despite low water tables, Federated Farmers adverse events spokeswoman Katie Milne said.
“Around Gisborne and Hawke’s Bay, they’re used to it, but it’s starting to get pretty ugly for some of them.”
Conditions for her own farm, a dairy operation at Rotomanu southeast of Greymouth, had been “hopeless”.
“We just keep getting these big storms coming through: we’ll get one fine day, a dayand-a-half of cloud . . . then we’re in for another 70mm to 300mm of rain.”
Rural fire crews had also noted the big contrast.
Most of this summer’s major blazes had been in the east, among them scrub fires that razed properties and forced evacuations in Whitianga and Wairoa, a bush fire that charred 100ha of Mt Horrible in Canterbury and a spate of suspicious fires in Marlborough’s Wither Hills.
Total fire bans remained in place for Hawke’s Bay, Gisborne, Marlborough, Northland, Coromandel and Otago.
“We’ve had lots of rain of the western side of the country. A little bit of that has gone up the East Coast and has taken some of the sting out of things, but with strong winds and temperatures in the 30s, that disappears very quickly,” said the National Rural Fire Authority’s rural fire manager, John Rasmussen.
An abundance of grass across dry areas meant there was more potential fuel for fires compared with previous summers. But Rasmussen hoped more settled, less windy weather expected in February would lower the threat.
With February bringing the peak of summer, there were no rain-making systems on the immediate horizon to ease dry conditions, said Philip Duncan of Weatherwatch.co.nz.
“Some longer-range models, which aren’t so reliable, perhaps show a rain-maker for some eastern areas in 11 or 12 days’ time, but our confidence is minimal about this.”
In the short-term, the east of the North Island and Northland were locked into an extended dry heatwave, with highs in the low- to mid-30s.
Duncan said a La Nina forecast for the summer months should have brought rain to the dry eastern areas, but the climate system had proven too weak to make a difference.
“With a continuation of this more ‘neutral’ pattern expected into late summer and early autumn, it opens our country up to weather from all four directions — a somewhat distant silver lining for some eastern areas, with the chance rain could land on any given week in February, despite it traditionally being the peak of summer,” the analyst said.
“However, for now it’s more of the same pattern we saw in late January but with one exception: The dry, sunnier days will be hotter.”