Despite a cool change currently moving up the South Island most of New Zealand is in for a much warmer week than last week predicts WeatherWatch.co.nz.
Head weather analyst Philip Duncan says conditions look warm with today’s southerly very short lived. “The southerly is a very weak one and while today in the south and east of the South Island will be affected by a cooler southerly it will be nothing like last week”.
10 days ago a cold southerly came through bringing snow to the mountains and frosts as far north as Central Plateau. The chill in the air remained for a number of days before easing gradually as last week ended. Today’s southerly isn’t strong with winds dying out as quickly as this afternoon.
“By Wednesday warmer winds move back into the South Island while the North Island remains warm, even hot, with highs in the low to mid 20s”.
Overnight lows have also slowly crept back up to average levels following last weeks cold snap. They are expected to remain where they are for most centres for the rest of the week.
Another front will move in to the south west of New Zealand on Wednesday and Thursday with conditions predicted to be settled almost everywhere by the weekend – although rain may affect the upper North Island on Sunday as a low from the northern Tasman Sea approaches.
– Image – File, Taranaki on a sunny day / Greg Taylor
on 14/03/2011 9:49pm
I understand that low pressure is caused by rotation and a thinner layer of atmosphere at the low’s centre. So why isn’t this centrifugal affect seen in high pressure systems, afterall the atmosphere is spinning too but in the opposite direction?
on 15/03/2011 1:21am
Thanks for the question. We thought such a scientific question should be answered by a scientist, so we asked friend of the site Dr James Renwick from NIWA for an answer – hope this helps!
James Renwick, NIWA
on 15/03/2011 1:48am
Thanks for the excellent explanation, I really appreciate it!
I guess one answered question often prompts another !!
The motion of air is out of a High, so how is it that high pressure systems can have such a long life, given that there would be a limited amount of air available to flow out?
on 15/03/2011 4:17am
Actually air pressures around the planet are even – so a very intense high needs to be counteracted by a a deep low, or series of low pressure systems, to even it all out. Some highs – the blocking ones – can last months (causing droughts) but there are also lows that can linger around the Southern ocean or tropics for many days or even weeks.