By Anne Hardie

A new forecasting tool being developed by NIWA is designed to forecast drought and dry conditions so farmers and growers can be better prepared.

NIWA meteorologist Ben Noll says scientists will use a weather model released in the United States in 2020 and refine it for New Zealand’s complex terrain. It will involve some “data science and deep learning” to understand the NZ context.

Initially it will be developed to forecast 35 days ahead and then it will be extended to three and then six months as researchers try to push predictions further out.

“We are trying to determine if a drought is likely,” he says. “Whether or not drought has a higher probability in the next two seasons.”

The new forecast tool will sit alongside the New Zealand Drought Index which was developed and launched in 2017. It measures the status of drought across the country and measures the duration and intensity of recent dryness. In other words, it is an observation of drought once it has happened.

NIWA also provides seasonal climate outlooks each month that look three months ahead, but they are not drought specific. The new tool will try and foresee the potential for dryness and drought and therefore limit the risk of being caught out by drought. Until now, NZ meteorology has been using a climate model with a 100km resolution which describes the distance between nodes on a grid.

That will move progressively toward a resolution of 5km which will in effect give them more detail for locations within NZ’s terrain.

Noll says NZ has many regions where mountains closely border farmland – such as Tasman – where current forecasting struggles to predict weather. Increasing the resolution will increase the ability to forecast within a region.

Past models looked at weather patterns such as El Nino and La Nina to predict seasons, whereas this model will take that information plus more data and techniques to better predict what lies ahead. Noll says there is huge potential to improve the accuracy of the modelling and then push it out to the masses through the web.

“The goal is to push the science as far as we can with current meteorology.”

The new forecasting tool will be available on the NIWA website at the end of 2023 and will supplement other tools used by farmers. Noll says it will give a bit more clarity for farmers and growers when they are planning. Earlier dry or drought warnings can help determine stocking levels, water storage and feed management options.

“There is going to be another summer like the one in 2019-20 and there will be more events with increasing frequency. So to have all our ducks in a row now will set New Zealand up as a nation to cope with those events.”

Development of the new tool will cost $200,000 and is being jointly funded through the Ministry of Primary Industries and NIWA.