Monthly Climate Statement for March 2014

The Science Delivery Division of the Department of Science, Information Technology, Innovation and the Arts (DSITIA) considers that there is a slightly lower than normal probability of exceeding median rainfall over the next three-month period (March to May) for parts of northern and eastern Queensland. This view is based on DSITIA’s analysis of the historical relationship between Queensland rainfall and the Southern Oscillation Index (SOI). Read more (PDF, 193K, last updated 12:02PM, 17 March 2014)*

DSITIA’s rainfall outlooks for Queensland are based on the current and projected state of the El Niño-Southern Oscillation (ENSO) phenomenon and on factors which alter the impact of ENSO on Queensland rainfall (e.g. the Pacific Decadal Oscillation (PDO)). Currently:

• The SOI, a key-atmospheric measure of ENSO, rose from a quite positive value (+11.2) in January to a slightly negative value (-1.7) in February. The three-month mean SOI value from December to February was +2.9, remaining in the ENSO-neutral range.
• The observed sea-surface temperature (SST) anomaly (-0.6 ºC) was below average in the key  Niño 3.4 region of the central equatorial Pacific in February.
• Most international global climate models (PDF)* indicate that central equatorial Pacific SSTs should warm, but remain within the 'ENSO-neutral' range, through autumn.
• At this early stage, most international models are suggesting a higher than normal probability of El Niño conditions developing over winter. However, seasonal outlooks, including outlooks for ENSO development, are least reliable at this time of year – a period known as the ‘autumn predictability gap’.

Close to 80 per cent of Queensland is now (as at 7 March) drought declared under state government processes.

Rainfall Outlook

There are various approaches used to provide rainfall outlooks. These approaches tend to differ in terms of methodology and, for this reason, each approach may convey a different outlook, particularly for specific locations.

Rainfall outlooks provided in this Climate Statement are based on:

• DSITIA’s experimental long-lead Seasonal Pacific Ocean Temperature Analysis version 1 scheme (SPOTA-1 scheme), which integrates SST information, including indices of ENSO and the PDO.
• DSITIA’s SOI Phase scheme, which relies solely on the SOI, an atmospheric measure of ENSO.

The experimental SPOTA-1 scheme provides long-lead probabilities of summer (November to March) rainfall for Queensland from mid-April through to mid-November each year. This outlook takes into account a monthly ENSO index, as well as an index of March SST anomalies which reflect the phase of the PDO.

As at 1 November 2013, the final SPOTA-1 assessment for this summer (November 2013 to March 2014) indicated a higher than normal probability of ‘near-average’ to ‘above-average’ rainfall for much of Queensland.

DSITIA’s SOI Phase scheme provides probabilities of rainfall for the coming three-month season based on SOI values over the previous two months. The SOI Phase scheme currently indicates that the probability of above-median rainfall for the next three-month period (March to May) is 40 to 60 per cent for most of Queensland, with lower probabilities for parts of northern and eastern Queensland. This analysis is based on the SOI being in a ‘Rapidly Falling’ phase at the end of February, as discussed further in the Australia's Variable Rainfall poster (PDF, 9.3M, last updated 03:09PM, 29 July 2016)*, or the department’s archive of historical rainfall maps).

Each climate outlook scheme may have its own particular following. Although such schemes cannot provide outlooks with absolute certainty, users of the information who follow a skilful scheme should benefit from doing so in the long term. Users should consider the historical track record of any scheme, and such information is becoming increasingly available. DSITIA's Long Paddock website provides an archive of SPOTA-1 reports and past commentaries on the SOI Phase scheme.

While DSITIA places emphasis on the SPOTA-1 and SOI-Phase analyses, a much wider range of information from national and international agencies is also considered. DSITIA pays particular attention to the Bureau of Meteorology’s 'ENSO Wrap-Up' (PDF)* which is updated fortnightly on the Bureau of Meteorology website.

ENSO influences other climate variables apart from rainfall (e.g. temperature, pan evaporation and vapour pressure). This means that the impact of ENSO on crop or pasture growth can be stronger than on rainfall alone. The impact of ENSO on pasture growth, for example, is also dependent upon current pasture condition and soil water status. DSITIA’s AussieGRASS model takes these factors into account in producing seasonal pasture growth probabilities. 

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