Wednesday, May 22, 2024

El Niño is officially here but effects felt for a while

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In other words, the weather pattern has been emerging for several weeks now and many around NZ have noticed the change to milder and drier conditions. 
The advent of El Niño is not all bad news, says Phil Duncan, and in fact recent conditions could be considered extremely favourable for pasture growth in the western side of New Zealand.
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It’s official: after months of waiting, El Niño is now finally here. The Bureau of Meteorology – widely seen as the Australasian climate experts – announced it on Tuesday September 19th. 

BoM uses its own strict criteria to measure sea surface and atmospheric conditions in the tropics and many expected the announcement a few weeks ago. 

But the announcement does little to change what is going on weather-wise around New Zealand. 

It’s a bit like we’ve gone from driving at 90km/h to now 100km/h and we’ve reached the open speed limit. 

In other words, the weather pattern has been emerging for several weeks now and many around NZ have noticed the change to milder and drier conditions. 

The recent rain will have been very welcome – and it’s worth noting that, as I’ve often repeated here, NZ’s location on Earth means the Southern Ocean weather systems give us wet weather, and that is forecast for Southland and West Coast over the coming several months. 

So does this mean every weather column from now on will just continue to repeat “hot and dry summer coming”?  

No, not at all. In fact there’s little point in obsessing about what are the well-known facts with El Niño. 

Instead, it makes sense to now paint a picture of what may happen – but balance that with silver linings. 

It’s not all bad news, and in fact recent conditions could be considered extremely favourable for pasture growth in the western side of the country.

An El Niño spring can be a little more showery for the western North Island. With the increased daylight hours and warmer airflows in the mix (off and on) from Australia and following on from a wet winter, it’s a great recipe for fast grass growth. 

My highly scientific way of monitoring pasture growth in northern NZ is how often I use my lawn mower. 

It gained dust in the garage over winter – but has been used twice in the past 10 days.  

At the other end of NZ, southerners have spoken about how mild soil temperatures are following a winter that had very limited frosty days. 

So over the months ahead we expect the usual spring dry to develop in eastern and inland parts of both main islands. 

On top of that, extra high pressure from Australia will sometimes bring with it warmer air from Aussie’s interior. (Also, with over 70 fires burning now in New South Wales alone, NZ can expect smokey/hazy skies from time to time. Australia’s bush fire season looks to be especially busy.) 

The Southern Ocean will provide NZ will some relief – and cooler air like this week – and the Tasman Sea may also briefly provide wet weather systems too (like this past weekend) . 

But we do need to be prepared for a reduction in rain over the coming several months.

Map shows expected rainfall from 7am Sunday September 24 through to 7am Sunday October 1.

Upcoming Highlights

• Cooler this week, some by several degrees

• Risk of frost for the lower South Island

• Colder pulse of air in southern NZ Tuesday

• More high pressure late week

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