Thursday, February 22, 2024

We can see clearly now the rain has gone

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There is no doubt that ALL forecasters got the eastern North Island’s outlook wrong, says Phil Duncan.
Under the new OverseerFM modelling, crops have a farm-specific growth curve and are more representative of what is actually happening in the farm system.
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By Phil Duncan, WeatherWatch

Three severe tropical cyclones and the cyclone season is only six weeks old … and we still have four and a half months to go. It’s unusual for any given year, let alone an El Niño one. Last week NIWA and Australia’s Bureau of Meterology (BoM) both rewrote their summer forecasts to match what the private sector in both nations has been saying for months now: we have an unusual El Niño weather pattern this year. 

Despite it taking a painful few months for NIWA to catch up, it is a relief to have WeatherWatch, NIWA and BoM all on the same page across Australasia now. 

Our long-range forecasts from winter looking through to about now have not changed much – you may not feel it, but there are many parts of NZ now drying out. 

But there is no doubt that ALL forecasters got the eastern North Island’s outlook wrong. No one expected so much repetitive rain to hover around there. 

Some people draw far too much of a conclusion from this: that all El Niño forecasts are wrong. But New Zealand is so small, these things can happen – and it doesn’t undo the global set-up. 

Running a farm means you need to manage it well – and long-range forecasts aren’t always perfect anywhere in the world, let alone for two mountainous islands smack bang alone in the Roaring Forties, where anything can happen. 

Being in tune with the long-range forecasts and also then applying your local knowledge and understanding of what that might mean for you will make the forecasts come to life better – knowing the variables (that is, the cyclone or stalled thunderstorm that can, thankfully, break a big dry forecast). 

For those of you frustrated it’s not as dry as you expected, and you’ve sold stock already to prepare – just remember, if farming was easy everyone would be doing it. Like forecasting, it takes trial and error, it takes learning from mistakes, and it takes some good gut instinct that must continually adapt to the latest and best data you have.

Despite the wet weather lately, there are parts of NZ drying out. I think the next couple of weeks are going to be critical ones when we all work out what is likely coming for January and February. 

Once we have those details we’ll be much clearer about whether or not we are facing serious dry conditions in 2024, or if our location on Earth, along with this “broken” El Niño weather pattern, is being extraordinarily kind to most of NZ as it was over spring (generally speaking of course, Hawke’s Bay & Gisborne!). 

In December it doesn’t take long for things to dry out fast.

This map shows the forecast rainfall for the week from December 10 and should make many in the eastern North Island happy!

Upcoming highlights

• More high pressure this week

• Cold fronts continue to brush lower South Island 

• Classic El Niño set-up with high pressure in the Tasman Sea and a southwest flow across NZ this week

• It’s possible a low will be over the Tasman Sea next week

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