NSW Seasonal Conditions Summary September 2015

Highlights

  • Rainfall during August was average across most of NSW. Above average rainfall occurred across areas of the Riverina and south east. Below average rainfall occurred across areas of the south west, northern central west and mid-north coast.
  • The rainfall and temperature outlooks are near-neutral over most of NSW between September and November. Wetter than normal conditions are likely in the west and warmer overnight temperatures in the north and east.
  • During September, wetter than normal conditions are likely across southern and western NSW.
  • The El Niño event has continued to strengthen and is likely to continue through spring and summer. Reduced spring rainfall, higher daytime temperatures and an increased risk of frost remain a possibility, although the effects to date have been moderated by warm Indian Ocean conditions.
  • Topsoil moisture levels were maintained in the south, but declined in the north and west. Subsoil moisture levels remained stable. Run off improved over the south, but remained low in areas of the north west, south west, central west, western Riverina and the tablelands.
  • Pasture growth improved across the Riverina and southern central west, and was maintained in the south and on the coast. Growth improved on the tablelands and slopes, but was slow due to cold temperatures and meant supplementary feeding continued.
  • Winter crop growth has been good, with near-ideal rainfall and timing except in some western areas. Yield potential will be average to above average if normal spring rainfall occurs. Prospects for summer cropping are poor in the south but variable in the north depending upon soil moisture levels.

Overview

Rainfall during August was average across most of the state. Above average rainfall occurred across 23 per cent of NSW, covering areas of the Riverina, southern and south eastern NSW. An area in the far west also received above average rainfall. Below average rainfall occurred over 7 per cent of NSW, and was primarily confined to the northern central west and north west, areas of the mid-north coast and the far south west.

August pasture growth was similar to July. Growth was maintained in the south and in coastal areas, and improved in the Riverina and southern central west. It declined slightly in areas of the north west, northern central west and far west. Although growth improved somewhat across the tablelands, Monaro and upper central west and south west slopes it remained slow due to cold, wet conditions. Waterlogging of pastures occurred over some areas of the south east and eastern Riverina.

Relative to historical records, pasture growth was average to above average across most of NSW. Areas of below average relative growth occurred in the north west, far south west and along the mid-north coast.

Biomass levels were generally stable. Biomass remained low across areas of the far west, the south east, tablelands, upper areas of the southern slopes and areas of the north coast. Levels were generally good across the central west, Riverina and southern NSW.

Supplementary feeding has ceased in many areas, although it remained necessary in some areas of the tablelands, eastern Riverina and mid-north coast due to slow pasture growth and limited biomass.

Rainfall during August maintained or improved winter crop prospects in most areas. Cereal crops in the southern and central areas range from jointing through to ear emergence, with the north generally further advanced and flowering crops beginning to fill grain. Early sown crops are well advanced, although not as advanced as last year following the warm winter conditions. Late sown crops have been slow to develop. Frosting remains a risk. Crop growth and yield potential for cereals and canola are generally good across most of the southern and central areas, except for areas of the far south west, the far western Riverina and the western margins of the central west. Yields in the latter areas will be reliant on follow up rainfall. The yield potential of late sown crops is variable depending upon nutrition and sowing date. Pulse crops have reasonable to good yield potential in the south. Waterlogging of some areas, particularly in the eastern/central Riverina, has affected pulse crops and caused trafficability issues. Crop growth and yield potential is also good across the north west to the east of the Newell Highway, but is lower in the west due to very late sowing and limited subsoil moisture. Yields in this area are dependent upon good follow up rainfall occurring.

Modelling by the Australian Export Grains Innovation Centre in mid-August indicated many areas have an above average wheat yield potential if they receive normal rainfall over the remainder of the growing season. Some areas of south west and the western areas of the central west have an average yield potential. Yield potential is below average for some areas of the western Riverina, the far south west and the western margin of the north west.

If the current El Niño event has a greater influence on rainfall and frost incidence during the remainder of September and early-mid October, crop yields may not reach their full potential.

Dual purpose winter crops and forage crops have been providing good production, particularly on the tablelands and slopes, but have now been locked up for grain recovery.

Prospects for summer crops will be limited by subsoil moisture reserves in some northern and central areas, and due to the availability and price of irrigation water in the south. Other areas of the north have good potential due to favourable soil moisture levels.

Topsoil moisture levels were maintained across much of southern and south eastern NSW and the central tablelands, but were low in the west and the north. They also declined across areas of the northern tablelands and the mid-north to north coast. Subsoil moisture remained low over areas of the north west, northern central west and far south west, but generally remained stable across most of the cropping areas. Subsoil moisture remained moderate to high across the tablelands and slopes and high along the coastal strip. 

Run off improved in the south of the state, but still remained limited in areas of the north west, northern and central tablelands, the central west and the south west and western Riverina. In these areas, stock water supplies remain variable.

NSW Seasonal Conditions Report – September 2015

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Seasonal outlook

The Bureau of Meteorology's rainfall and temperature outlooks are near-neutral over most of NSW for September and November. This means there is a near-equal chance of drier or wetter than normal conditions and for cooler or warmer than normal temperatures. Wetter than normal conditions are likely in areas of western NSW. Warmer than normal daytime temperatures are likely across the central to north coast and lower Hunter valley, and cooler temperatures across areas of the far south. Warmer than normal overnight temperatures are likely across north eastern and most of eastern NSW as well as areas of the north.

During September, wetter than normal conditions are likely across much of the southern and western NSW, the Riverina and areas of the central west. There is a near-equal chance of drier or wetter than normal conditions over much of eastern, north eastern and north western NSW. Cooler than normal daytime temperatures area likely across most of southern and central NSW, with warmer temperatures likely in the far north east and near-neutral conditions in the north and Hunter valley. Overnight temperatures are likely to be warmer over areas of the north and north east and near-neutral elsewhere.

Of the global climate models surveyed, most suggest drier than normal conditions across areas of NSW between September and November. About 20 per cent suggest wetter than normal conditions between September and November. The remainder suggest near-neutral conditions. The majority of models suggest conditions will be warmer than normal. Note that this does not indicate a reduced frost risk.

The pasture growth outlook for September to November suggests generally below average growth for the tablelands, slopes, plains, far north west and north coast. Above average growth is suggested for the south eastern edge of the rangelands and areas of the far south west. Average growth is suggested for the lower Hunter, central coast and most of the south east. Skill levels for the outlook are moderate to high across most of NSW. However, the rainfall outlook that this is based upon is inconsistent with that of the Bureau of Meteorology. The growth outlook is based upon a consistently negative SOI during July/August, linked to the possibility of well below average rainfall across much of inland NSW and generally average rainfall across the south to mid-north coast. As the Bureau of Meteorology's rainfall outlook is more positive, pasture growth may be better than indicated across most of the state.

El Niño Southern Oscillation (ENSO)

The Pacific Ocean remains in an El Niño event, and this has continued to intensify with sea surface temperatures in the central Pacific continuing to rise. Global climate models indicate that the El Niño event is likely to persist through spring and summer. Some climate scientists consider that there is a possibility a La Niña event may follow in 2016, particularly if a positive Indian Ocean Dipole event occurs this spring. The Bureau of Meteorology's ENSO tracker status remains at 'El Niño'.

The SOI and equatorial Pacific sea temperatures, trade wind and cloud conditions are consistent with an El Niño event. Warm sea surface temperatures anomalies extend across the central and eastern equatorial Pacific, and strengthened during August in the central areas. Sea surface temperatures cooled in the west. Sub-surface warm temperature anomalies remain across most of the central to eastern equatorial Pacific to a depth of 100-200m.

An El Niño event is generally associated with below-average rainfall across NSW (particularly inland NSW) during winter and spring, above average daytime temperatures, lower than average streamflow and an increased risk of frost.

Its effects continued to be moderated by average to warm sea surface temperatures to the west and north west of Australia during August, which provided sources of moisture for NSW. However, the cooling of sea surface temperatures to the north, north east and more recently to the north west of Australia and along the Western Australian coast is of concern.

The cooling of the eastern Indian Ocean near Sumatra is reflected in the Indian Ocean Dipole (IOD) moving into the positive range during August. Three out of five climate models are suggesting a positive IOD event during September and two out of five in November. Such events are associated with drier than normal conditions in NSW, and tend to enhance the El Niño effects.Sea surface temperatures in the Indian Ocean further to the west and south west of the continent remain average to above average and may continue to moderate the effects of the El Niño event.

Climatic outlook summary

NSW Seasonal Outlook Current outlook Previous outlook
Quarterly Rainfall

Near neutral – neutral
(most of NSW)

Wetter 
(western NSW)

Near neutral - neutral          
(most of NSW)

Drier 
(far south east, north east)

Quarterly Maximum Temperature

Near neutral – neutral
(most of NSW)

Warmer
(central - north coast, lower Hunter valley)

Cooler 
(areas of the far south)

Near neutral - neutral
(most of NSW)

Warmer
(coast, northern NSW, Hunter valley, northern tablelands)

Quarterly Minimum Temperature

Warmer
(northern, north eastern and central NSW)

Near neutral - neutral
(most of NSW)

Warmer

El Niño Southern Oscillation (ENSO)
ENSO (overall) El Niño El Niño
BoM ENSO Tracker Status El Niño El Niño
SOI Negative Negative
Pacific Ocean (NINO3.4)

Warm
(Above El Niño thresholds)

Warm
(Above El Niño thresholds)

Indian Ocean (IOD) Trending towards a positive IOD event Neutral - positive
Southern Annular Mode (SAM/AAO) Near neutral - slightly positive Slightly positive - near neutral         

Rainfall and temperature

During August, rainfall across the state ranged from 3-489 mm. Heavy falls occurred across the southeast late in the month. An east coast low caused heavy falls and flooding across the Illawarra and adjacent areas of the south coast.

Falls over most of the state ranged from 10-50 mm. Areas of the south east, northern tablelands, northern slopes, upper Hunter, central tablelands and eastern Riverina received 50-100 mm. The alpine areas received 100-200 mm and areas of the Illawarra received over 200-300 mm.

The lowest recordings of 1-10 mm occurred in a belt across the north west. The mid-north coast received 10-25 mm. Rainfall was generally between 25-50 mm across the central and eastern areas of NSW. 

During August, daytime temperatures were cooler across much of the south, west and central areas of NSW. Temperatures were warmer in the north east but near normal elsewhere. Overnight temperatures were cooler across the northern and central areas of the state, and areas of the far west and far south, but near normal elsewhere.

Relative rainfall

Relative to historical records, rainfall during August was above average across 23 per cent of the state, average over 68 per cent and below average over 7 per cent.

Areas in the far west around Broken Hill, the eastern and central Riverina, the far south and the south east received above average relative rainfall. Some areas of the upper Hunter valley and northern slopes also received above average rainfall. Areas of the northern and south western central west, mid-north coast and far south west received below average rainfall, as did isolated areas of the north west. 

Quarterly relative rainfall was above average across 45 per cent of the state, including much of western and south eastern NSW and the central and eastern Riverina. Some areas of the north west and central west also received above average rainfall. Rainfall was below average across much of the central and mid-north coast and areas of the far south west, north coast and northern tablelands.

Soil moisture

Moderate modelled topsoil moisture levels were maintained across the south, south east, most of the central tablelands and the southern central west, but declined elsewhere. Relative to historical records, topsoil moisture was generally average but below average in areas of the north east. It was above average across areas of the south east, Riverina and the central areas of the far west. 

Modelled subsoil moisture levels improved across the south east and were maintained in the central and eastern areas of the state. Relative to historical records, subsoil moisture remained below average across areas of the north west and far western Riverina.

Streamflow

Run off continued to improve across NSW, particularly the south of the central west and the central and eastern areas of the Riverina. However, in many areas it remained variable. Run off was low in the north of the central tablelands and the western areas of the central west, north west, Riverina and the far south. 

The Bureau of Meteorology's streamflow forecast indicates generally low streamflows are likely across most inland southern NSW monitoring stations during September to November, with some tending towards near-median. A mix of low and near-median flows are likely at central NSW monitoring stations and in areas of the north. Near-median flows are likely in the far north east. Near-median to high streamflows are likely in southern coastal locations.

Relative pasture growth and biomass

Relative to historical records, AussieGRASS modelled pasture growth for August was average to above average across most of the state. Areas of below average growth occurred in the north west, mid-north coast and far south west.

Other pasture growth models indicated well above average growth for temperate pastures across areas of the far west and the central areas of the state. Growth for the coast was generally average. It was below average across the slopes, tablelands, Monaro and areas of the south east.

Over the quarter, AussieGRASS relative growth was generally above average across the western and central areas of NSW, and average in the east.

During August, relative biomass levels improved slightly. They remained high across areas of the central west and central tablelands, the northern tablelands, northern slopes and areas of the far south and far west. Over most of the south, west and east of the state, relative biomass levels were average.

Figure 1: Relative monthly topsoil moisture

Soil moisture map 

Figure 2: Relative quarterly pasture growth

Pasture growth map 

More information

For more information, contact the NSW Department of Primary Industries on 02 6391 3100 or Local Land Services on 1300 795 299.

Acknowledgments

Information used in this report was sourced from the Australian Bureau of Meteorology, CSIRO, the Queensland Department of Science, Information Technology and Innovation, the Australian Export Grains Innovation Centre, the Queensland Alliance for Agriculture and Food Innovation, the U.S. Department of Agriculture, U.S. Department of Commerce, the U.S. National Oceanic and Atmospheric Administration, the International Research Institute for Climate and Society (Columbia University), the UK Meteorological Office, the APEC Climate Centre, NSW Local Land Services and NSW Department of Primary Industries.

External links

Disclaimer

The seasonal outlooks presented in this report are obtained from the Australian Bureau of Meteorology and other sources. These outlooks are general statements about the likelihood (chance) of (for example) exceeding the median rainfall or minimum or maximum temperatures. Such probability outlooks should not be used as categorical or definitive forecasts, but should be regarded as tools to assist in risk management and decision making. Changes in seasonal outlooks may have occurred since this report was released. Outlook information was up to date as at 10 September 2015.

Recognising that some of the information in this document is provided by third parties, the State of New South Wales, the author and the publisher take no responsibility for the accuracy, currency, reliability and correctness of any information included in the document provided by third parties.

The information contained in this publication is based on knowledge and understanding at the time of writing (10 September August 2015). However, because of advances in knowledge, users are reminded of the need to ensure that information upon which they rely is up to date and to check currency of the information with the appropriate officer of the Department of Primary Industries, Local Land Services or the user's independent adviser.