THE CLIMATE KELPIE BLOG: Meet the expert – Meredith Guthrie, DPIRD

Posted by BCG on 31st May 2018

What does your job involve?

I run DPIRD’s Statistical Seasonal Forecast (SSF) which is a seasonal outlook for the south west region of Western Australia.

This model is run every month and gives an outlook up to three months ahead, while also giving a May to October (growing season) outlook.

I write a monthly newsletter, Seasonal Climate Outlook, which is published on the DPIRD’s website, plus I produce plant available soil water, potential yield, rainfall to date and frost risk maps and I also provide climate data and climate analysis for the WA grainbelt.

What are the most important climate drivers’ Western Australian farmers should have a good understanding of?

The most important climate drives for Western Australia are:

  • The Sub-tropical Ridge – a band of high pressure across mid-latitudes which moves north (towards the equator) in winter and south (towards the southern pole) in summer. From November to April it can block cold fronts for days, or even weeks, at a time. From June to August it moves north, allowing cold, moist air to create rain.
  • Indian Ocean Dipole (IOD) – the difference in sea surface temperature (SST) between the western and eastern Indian Ocean. Generally this only effects the eastern grainbelt in May to October. A negative IOD can result in more rain, while a positive IOD can result in less rain.
  • Southern Annular Mode (SAM) – the north-south movement of the westerly wind belts that circles Antarctica. SAM drives cold front movement and influences the climate all year round.
  • El Niño Southern Oscillation (ENSO) – ocean and atmosphere conditions in the Pacific Ocean. ENSO has limited influence for Western Australia. An El Niño in winter/spring can result in lower than average rainfall due to a weaker Leeuwin current.

It’s also important to look at SST in the northern Indian Ocean and the Southern Ocean. If the waters are warmer than normal, this will increase the moisture uptake needed to produce rain.

What are some of the decisions Western Australian farmers make where they should be referring to seasonal climate forecasts?

Research has shown that the SSF has good skill in the northern and central grain belt in May through to July.

Farmers in these areas can use the SSF to make decisions about what and how much to sow (if sowing later than April) and also how much nitrogen (N) to apply at seeding.

The May to October outlook produced by the SSF has also proven to have skill in the northern and central grainbelt. Looking at this outlook can help with decisions around stocking rates and later N applications.

What’s been the biggest change that you’ve seen in seasonal climate forecasting over your career?

The biggest change has been the development of the SSF in 2012 which doesn’t focus on ENSO.

It is important to know that ENSO does not influence our WA climate in the way it does over the eastern states which are closer to the Pacific Ocean.

It will also be exciting to see the Bureau of Meteorology’s (BoM) new ACCESS-s model which may provide better temperature and rainfall outlooks for WA.

Where do you see seasonal climate forecasting heading in the future?

Better skill in dynamical seasonal forecasting as errors in global modelling are corrected. It’s exciting to see work happening in this space with Monash University and the Bureau of Meteorology as part of Rural R&D for Profit funded projects.

How can a farmer contact you and what questions can you help them answer?

I can help them answer questions about seasonal outlooks, climate drivers and decision support tools.

Email: meredith.guthrie@dpird.wa.gov.au

Phone: (08) 9368 3058