Wednesday, May 22, 2024

Weather patterns showing some positive signs 

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Because of the chaotic weather pattern this year, basically every part of the country has had soaking rains and warmer than average temperatures.
Monday kicks off with a westerly flow over NZ
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By Phil Duncan, WeatherWatch

The regions with some of our most settled weather often don’t get talked about. Severe weather usually makes the headlines, so if you’re in a part of New Zealand that’s had calm, steady weather in recent months you may feel a bit left out. 

Because of the chaotic weather pattern this year, the varying wind directions and airflows mean basically every part of the country has had soaking rains and warmer than average temperatures. But there are some areas that are leaning slightly drier – and with a spring pattern nearby that usually means more westerlies and drier spells in the mix.

As far as soil moisture is concerned, much of the country (around 90% of NZ) is at “field capacity”, meaning the ground can’t absorb more water and so additional rain will become surplus, leading to ponding and surface flooding and, yep, more mud. 

Those areas in surplus lately have been mostly in Canterbury with that easterly-driven rain several days ago.

But there are a few spots dropping to around half of the soil moisture capacity – and that, at the time of writing, was also in the same region with too much water, Canterbury. It highlights how even within one region you can be both too wet and becoming a bit dry. 

Surprisingly, given the winter we’ve had, the state of soil moisture levels around NZ is pretty much ‘normal’.

South Canterbury and North Otago are the areas that aren’t as wet as other parts of NZ – not surprising really, this is traditionally NZ’s driest area. Otago, much like Canterbury, is also seeing a mixture of areas that have had too much rain (closer to the east coast) and areas that aren’t so wet (northern Otago).

Here’s something that may surprise many of you: currently the state of the soil moisture levels around NZ is pretty much “normal”. Areas that are wetter than normal are mostly in the east of the South Island from that rain event several days ago (parts of Marlborough, a lot of coastal Canterbury and some parts of coastal Otago). 

Waikato and Bay of Plenty are about normal for this time of year now after being in water surplus for several weeks before this. That means that even though it’s still been wet quite lately, the overall totals are dropping.

And that’s really what this week’s column is all about: taking note of where we are now – and being prepared for a potentially drier pattern to emerge for the rest of this year as El Niño grows. 

he rainfall deficit map shows that in most of New Zealand the ground can’t take much more water.

Our next monthly ClimateWatch update will be out this Wednesday – so in our Farmers Weekly column next week we’ll be exclusively breaking down why United States forecasters have announced El Niño is here, but Australian and New Zealand forecasters are taking longer – and what the general outlook is shaping up to be for spring and summer.

Weather highlights this week:

• Monday kicks off with a westerly flow over NZ

• A classic cold front moves up NZ Tue/Wed 

• High pressure from the Tasman Sea late week for the North Island

• Another classic cold front for the South Island on Fri/Sat

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