KEY POINTS:
After a week of weather extremes last week (see our quick week in review here) this week is shaping up to be less dramatic but still unsettled.
I think the settled weather of January is definitely over and we're seeing a change to more text book La Nina weather. The sea between Queensland and Fiji is especially active at the moment helping to produce many lows. This time last year we were also in La Nina (which usually brings wetter, muggier, weather to northern New Zealand and dry conditions to the South Island's eastern and central areas) but last year a large high held firm over the nation blocking all rain from getting in.
This summer, that high pressure zone has been in the Southern Tasman Sea, basically centred between Tasmania and Fiordland. It's this high that sucked down hot desert winds into Victoria and brought recording breaking heat to eastern parts of New Zealand. As I said the other day, high pressure systems "breathe"...by that I mean they grow big then shrink back, grow big again, shrink back again. Last year when our high shrank back it just exposed our northern and southern fringes to cloudier, windier, weather. This year, when that high in the Tasman shrinks back, it shifts its protective ridge back into the Tasman and opens New Zealand up to humid, hot weather moving down from the north and cold, showery weather moving in from the south.
This week things change a little though. The high in the Southern Tasman Sea is likely to be pushed further south, into the Southern Ocean and skirting around into the Pacific. Between big lows in the far south and tropical lows in the far north, the high may get squashed like a pancake under New Zealand and slip up the east coast - giving southern and eastern areas a dry, settled end to the week but allowing potentially heavy rain in the west and north of both islands. In fact, the low could become quite a big one bringing more rain relief to dry farms - but perhaps not much to those in the east that need it most. Click here to see the long range weather maps for this Thursday and Saturday.
Auckland and other northern regions may also see a return to humid weather during this week. At this stage no repeat of the extreme heat and humidity we saw combining last week but it may still be pretty muggy. Most likely this Thursday and Friday.
Personally I'm turning into one of those people who complains about the weather now!! Last week was too hot for me - this weekend was too cold...I'm a hard man to please! My preference for summer weather is what we saw in January - really hot days but relatively low humidity. The weekend felt very Autumn-like for most New Zealanders...and most kiwis recognise March 1st as the first day of Autumn so I guess it isn't far off really! For those who love the heat don't panic yet - we're at the peak of the hot season and while we may see the beginnings of colder weather on the horizon we should still see some scorching hot weather, high humidity and long warm evenings for a number of weeks yet before the summer weather finally eases.
Philip Duncan
