After a wet, wild and sometimes freezing September, most Kiwis can look forward to a warmer and calmer October, a forecaster says.
And Aucklanders, especially, should make the most of this month’s weather, before a La Nina climate system arrives to put a dampener on summer.
The month’s weather is predicted to be dominated by a westerly flow, bringing Auckland and the rest of northern New Zealand drier than normal conditions.
“Compared to September, I think a lot of people will really notice the weather getting warmer and especially drier,” Niwa meteorologist Ben Noll said.
“And there was no real theme to September, as there were so many things going on, from relatively warm days, to bomb cyclones and Antarctic outbreaks, and everything in between.”
With dominant high pressure systems – and a key climate indicator called the Southern Annular Mode switching to a positive phase – Noll said much of the country could expect weather more typical of November, or even December.
“It’s obviously quite warm this weekend, and for a range of regions early next week, we could see temperatures in the upper-20s.”
He said the general warm pattern would be broken up by a short-lived cold snap forecast for mid-next week.
“But by the second week of the month, we should see a return to warmth, especially in eastern regions, where we can expect the highest readings.
“Then, as we go into the second half of the month, we’ll start to see a pattern that’s more aligned with La Nina, with a ridge of high pressure perhaps centring itself over the South Island.
“By the time October is over, I think everyone will have had a small taste of summer.”
The irony for northern and eastern regions was that their summer could well prove a wet, albeit warm, one, as a La Nina system picked to be moderate in strength properly bedded in.
“I would really describe the next two weeks as a kind of interlude between what we saw in September, and the La Nina pattern really arriving,” Noll said.
“So for places like Auckland, Northland, the Bay of Plenty and Gisborne, it might be a nice stretch of weather to really enjoy because, as we go later into the year, those places aren’t necessarily guaranteed to get that.
“As for Wellington, which really took it on the chin during September with a lot of wind and some flooding, people there can expect some blustery westerlies over the next few weeks, but much less rainfall as we go into the second half of October.”
Further into 2020, strengthening La Nina conditions, and increased north-easterly flows, could spell yet more pleasant conditions for the capital.
Nationally, Niwa’s latest seasonal outlook predicted above average temperatures for the rest of 2020, along with an elevated chance of high temperature extremes – particularly on days with a strong northwest wind.
Air pressure, too, was forecast to be higher than normal to the southeast and lower than normal to the north of New Zealand.
While Australia’s Bureau of Meteorology has just formally declared a La Nina system has developed in the tropical Pacific, Niwa was, for now, keeping its La Nina watch status at “alert”.
Climate scientist Professor Jim Salinger said he expected the coming La Nina to be a moderate level event – or similar in scale to one that played out in 2011-12.
He predicted it to peak around December and January, with a switch from northwest to northeast prevailing winds around the close of spring.
Published at Sun, 04 Oct 2020 01:02:03 +0000