Monthly Climate Statement for February 2014

The Science Delivery Division of the Department of Science, Information Technology, Innovation and the Arts (DSITIA) considers that there is an equal likelihood of above-median and below-median rainfall for much of Queensland for the next three-month period (February to April). This view is based on DSITIA’s analysis of the historical relationship between Queensland rainfall and the Southern Oscillation Index (SOI). Read more (PDF, 205K, last updated 12:03PM, 14 February 2014)*

On 31 January, tropical cyclone ‘Dylan’ made landfall on the Queensland Central coast between Bowen and Proserpine, causing localised high rainfall. On 3 February, tropical cyclone ‘Fletcher’ made landfall in the Gulf, near Karumba, bringing high rainfall to parts of the Far North. The possibility remains of more tropical cyclones making landfall over Queensland before the end of the current cyclone season (November to April).

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 slightly negative value (-0.7) in December to a quite positive value (+11.2) in January. The three-month mean SOI value from November to January was +6.9, just remaining in the ENSO-neutral range.
• Although the observed sea-surface temperature (SST) anomaly (-0.5 ºC) was below average in the key Niño 3.4 region of the central equatorial Pacific in January, it remained in the ENSO-neutral range. 
• Most international global climate models indicate that central equatorial Pacific SSTs should remain within the 'ENSO-neutral' range leading into autumn.
• Some global climate models continue to indicate increased potential for warmer than normal central Pacific SSTs from mid-2014. The possibility of El Niño development will become clearer once we pass the ‘autumn predictability gap’.

Approximately 70 per cent of Queensland was drought declared under state government processes as at 28 January. Barcaldine, Bulloo and Longreach are the most recent regional council areas to be fully drought declared.

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 current ‘cool’ 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 (February to April) is 40 to 60 per cent for most of Queensland. This analysis is based on the SOI being in a ‘Rapidly Rising’ phase at the end of January, 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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