NSW Seasonal Conditions Summary January 2015

Highlights

  • Rainfall during December eased dry conditions across areas of the north west, coast, tablelands and central west, but was variable due to storms. Rainfall was generally above average across eastern NSW.
  • Over the last year, rainfall was below average over areas of the north west, northern tablelands, mid-north to north coast and Hunter valley. Areas of the Riverina, central west and central tablelands were also affected. Severe rainfall deficiencies occurred across the north west and northern tablelands over the last 18-24 months.
  • There is a near-equal chance of drier or wetter than normal conditions across NSW between January and March. Conditions are likely to be warmer than normal across most of NSW during this period.
  • January has a neutral rainfall outlook, with warmer than daytime and overnight temperatures likely across areas of the north west and far south east.
  • ENSO remains neutral, with several indicators weakening during December. If an El Niño event does occur, it is likely to be weak and only extend into early autumn.
  • Topsoil moisture levels improved across eastern and east-central NSW, but remain low in the west. Subsoil moisture levels were generally stable, with some declines in central NSW.
  • Recent rainfall has improved yield prospects for summer crops, and benefited the growth of lucerne and pastures. Some weather damage occurred in horticultural crops. Particular improvements in pasture growth occurred across the tablelands, Monaro and coast.
  • Resources to assist in management for areas suffering poor rainfall and growth are available at Managing drought.

Overview

Rainfall during December was above average across 58 per cent of NSW, and average to near average across 40 per cent of the State. However, its distribution was variable due to thunderstorm activity. Rainfall over eastern NSW was generally well above average to extremely high. However, rainfall was less than 60-80 per cent of normal across much of the southern and central areas of western NSW and the Riverina. The falls eased dry conditions across areas of the north west, far north west, coast, tablelands and central west.

Daytime temperatures were above average across much of western, central and north eastern NSW, and overnight temperatures were above average across most of the State.

Over the last year, rainfall was below average over areas of the north west, northern tablelands, mid-north to north coast and Hunter valley. Areas of the Riverina, central west and central tablelands were also affected. Severe rainfall deficiencies occurred across the north west and northern tablelands over the last 18-24 months.

The recent rainfall has benefited summer-growing pastures and lucerne, as well as dryland and irrigated summer field crops. It was generally too late to benefit spring fodder conservation from pastures. However, it has improved the yield prospects of summer field crops, particularly sorghum, sunflowers and cotton. Follow up rainfall will be essential for dryland crops as soil moisture reserves are generally still limited. The storm rainfall caused losses in cherries, caused weather damage in late harvested cereal crops and has further degraded the quality of standing dry feed. The warm temperatures during spring and summer have hastened the maturity of some horticultural crops.

The rainfall and warm temperatures benefited the growth of pastures across the tablelands, coast and Monaro, and across areas of the upper slopes and the central west. There was some improvement in growth across far north western NSW. Pasture growth remained low across southern and central areas of the far west, the western edge of the central west, the western Riverina and across areas of the north west.

Biomass levels improved across the east of the State, but remained low across much of western and central NSW.

Yearly streamflow analysis continued to indicate below average run off over areas of the north west, tablelands, central west, Riverina, far west and central to north coast. However, recent storm rainfall has resulted in some run off, particularly across areas of the coast and tablelands.

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Seasonal outlook

The latest Bureau of Meteorology seasonal outlook indicates a near-equal chance for drier or wetter than normal conditions between January and March. There is a slightly reduced chance of wetter than normal conditions across the far west, north west and north east of NSW. Warmer than normal overnight temperatures are likely across NSW. Warmer daytime temperatures are likely over most of NSW except across areas of the far north east, southern and central tablelands and the south east.

During January, there is a near equal chance of drier or wetter than normal conditions across most of NSW. Warmer daytime temperatures are likely across the far north west, north west, northern areas of the central west and the far south east. For the rest of the State, there is a near-equal chance of cooler or warmer than normal daytime temperatures. There is a near-equal chance of cooler or warmer than normal overnight temperatures across most of the State, although warmer than normal temperatures are likely in areas of the south east, north west and northern central west. More recent (unofficial) outlooks suggest wetter than normal conditions across most of NSW during the remainder of January. The indicate cooler than normal daytime temperatures across most of NSW, and cooler than normal overnight temperatures most of NSW except the north east and areas of the north west..

El Niño Southern Oscillation (ENSO)

ENSO remains neutral, with several indicators weakening over late December and early January, and reducing the likelihood of an El Niño event occurring in the near future. However, the Bureau of Meteorology's El Niño status remains at 'alert' level.

Sea surface temperatures have cooled since late December, but warm anomalies are still present across much of the equatorial Pacific, decreasing slightly in the central and eastern-central areas. The sea surface temperature anomaly in the key NINO3.4 region is currently +0.5°C (as at 4 January), over half a degree less than it was in late November. This is once more below the Bureau of Meteorology's El Niño threshold of +0.8°C. The anomaly level in the NINO3 region is +0.47°C, and is +0.8°C in the NINO4 region.

Sub-surface temperature anomalies have decreased since November-December, particularly in the central and eastern Pacific. A cool anomaly has developed at depth in the eastern-central Pacific. The SOI has weakened slightly since late December and is currently towards the lower end of the neutral range at a level of -6.5 (as at 7 January).

Rainfall during December remained below average near the junction of the equator and International Date Line, and was above average across Indonesia. Trade winds were near average, but may weaken over the next few weeks with the passage of the Madden-Julian Oscillation into the western Pacific. This may result in further warming of sea surface temperatures in this area.

If an El Niño event does occur, the global climate models currently favour a weak event ending in early autumn and then a return to neutral conditions.

Sea surface temperatures have increased to the north west of Australia, which is positive for rainfall across south eastern Australia.

Climatic outlook summary

NSW Seasonal Outlook Current outlook Previous outlook
Quarterly Rainfall Near neutral - neutral

Drier
(majority of NSW)

Near neutral
(far south west and north east)

Quarterly Maximum Temperature

Warmer

Near neutral
(far north east, areas of central/southern tablelands and south east)

Warmer
Quarterly Minimum Temperature Warmer

Warmer

Near neutral
(far south west)

El Niño Southern Oscillation (ENSO)
ENSO (overall) Neutral –
El Niño possible/likely
Neutral –
El Niño likely
BoM ENSO Tracker Status El Niño Alert El Niño Alert
SOI Neutral (currently weakly negative) Moderately negative
Pacific Ocean (NINO3.4) Slightly warm/warm
(Neutral – some models)
Slightly warm/warm
(Neutral – some models)
Indian Ocean (IOD) Neutral (currently slightly negative) Neutral
Southern Annular Mode (SAM/AAO) Weakly negative – weakly positive Weakly – moderately positive

Rainfall and temperature

Rainfall across NSW during December ranged between 0-400 mm, with most of the State receiving 10-200 mm. Rainfall tended to occur as a result of storms, and was very variable. Dry conditions were eased across the coast, tablelands, parts of the north west and some central areas of NSW. The amount of rainfall received increased towards the east, with areas of the upper slopes, tablelands and coast receiving 100-300 mm. The central area of the State including much of the north west, central west and eastern and northern Riverina generally received 25-100 mm.

The lowest recordings were across the southern and central areas of the far west and areas of the Riverina, where falls ranged from 0-25 mm. The north west generally received falls of 25-100 mm, with the worst drought affected areas receiving 25-50 mm. In the south, areas in the western Riverina near Hay and Balranald received only 1-10 mm, as did an area between Ivanhoe, Broken Hill and Tibooburra. Falls of 200 mm or more occurred across areas of the north coast, the east of the northern tablelands, areas of the mid-north coast and Hunter valley, the east of the southern tablelands and Monaro, the alpine areas and areas of the south coast. Isolated areas of the north and south coast received 300-400 mm.

Daytime and overnight temperatures were 1.5°C warmer than average across NSW during December, with the month being the tenth warmest on record for minimum temperatures.

Relative rainfall

Relative to historical records, rainfall during December was above average across 58 per cent of NSW. Above average rainfall occurred across much of the coast, tablelands, central west and far north west of NSW. Rainfall in the far south west and western areas of the Riverina was at the lower end of the 'average' range, with areas of below average rainfall to the north and east of Broken Hill, near Hay and south east of Wagga. Rainfall in these areas was less than 40-60 per cent of normal.

Quarterly relative rainfall was below average over 35 per cent of the State, including most of far south western NSW and areas of the north west and Riverina. Above average rainfall for the period was restricted to 7 per cent of NSW, primarily in the south east. Half yearly relative rainfall was below average across 47 per cent of NSW. Areas of below average rainfall for the period occurred across the far south west, Riverina and north west, but also extended to areas of the central tablelands, central west and northern tablelands. Areas of well below average rainfall occurred across the south and southern Riverina. Above average relative rainfall for the period (9 per cent of the State) was generally restricted to the south east and north coast.

Yearly relative rainfall was below average across 27 per cent of NSW. Areas of below average rainfall for the period extended across the north west, northern tablelands, north coast and Hunter valley, as well as areas of the far south west and western Riverina between Hay and Balranald. For the two years to December, below average relative rainfall extended across much of the north west and northern tablelands. Other areas extended across the Riverina, the north of the central west and the west of the central tablelands. Areas of extremely low relative rainfall occurred across the north west between Goodooga, Walgett, Collarenebri, Coonabarabran and Narrabri, and across the northern slopes and tablelands from Tamworth to Armidale and Glen Innes. Other areas of extremely low relative rainfall over the period occurred in the central tablelands around Mudgee, and in the Riverina around Hay.

Soil moisture

Modelled topsoil moisture levels improved across eastern and eastern-central NSW during December, with 30 per cent of the State shifting from low to moderate levels. Topsoil moisture levels improved slightly in the west of central NSW and across the north west, but still remained in the low range. Relative to historical records, topsoil moisture was average across most of western and central NSW. It was above average across the coast, Monaro and southern tablelands, as well as across areas of the central and northern tablelands, far north west and the north coast.

Modelled subsoil moisture levels were generally stable, with some declines across the central tablelands, central west and Riverina. Relative to historical records, subsoil moisture remained below average across the north west, northern tablelands, areas of the mid-north to north coast, the central tablelands and the Riverina. Areas of extremely low subsoil moisture extended across areas of the north west, northern tablelands, north coast, central tablelands and in the Riverina around Hay.

Streamflow

Streamflow analysis over the last one to two years has indicated below average run off over areas of the north west, tablelands, central west, Riverina, far west and central to north coast. However, recent storm rainfall has resulted in some run off, particularly across areas of the coast and tablelands.

Relative pasture growth and biomass

Relative to historical records, AussieGRASS modelled pasture growth showed a dramatic improvement between November and December across most of the State. Relative growth was below average over just 8 per cent of NSW, average over 34 per cent and above average over 27 per cent. However, there were large areas of missing data from the modelling, particularly in the west. Below average relative growth was restricted to areas of the north west, Riverina the south of the far west, and some northern areas of the central west. Above average relative growth occurred across the coast, tablelands, Monaro and upper slopes. Extremely high levels of pasture growth occurred across the south east, southern tablelands, Monaro and the northern tablelands.

Alternative pasture growth models also indicated well above average growth from temperate pasture species across most of the coast, tablelands and Monaro, areas of the upper slopes and the eastern areas of the central west. Well above average growth was indicated across most of the south east and Monaro. Growth between Walgett and Goodooga, near Moree, between Cobar and Bourke, between Hay and Balranald and between Ivanhoe, Broken Hill and Tibooburra was below average or worse. Good growth from tropical pasture species was indicated across the mid-north to north coast and Hunter valley.

Over the three months to December, relative growth remained low over the south west, north west, Riverina and the central areas of NSW. Relative growth for the period was also low across the western half of the tablelands. However, it was average along the coast, the eastern half of the tablelands, the south east and areas of the far north west. The best growth for the period occurred in areas of the Monaro and far south east.

Relative biomass levels remained low across the north west, the east and south of the central west, the west of the central tablelands and the Riverina. Relative biomass improved across the northern tablelands, the east of the central tablelands, the coast, the Hunter valley, the southern tablelands and the Monaro. Levels were greatest in the south east of NSW. Some 64 per cent of NSW had average or above average relative biomass levels.

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 1300795299.

Acknowledgments

Information used in this report was sourced from the Bureau of Meteorology, CSIRO, Queensland Department of Science, Information Technology, Innovation and the Arts, NSW Local Land Services, the US National Oceanic and Atmospheric Administration, the International Research Institute for Climate and Society (Columbia University) 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 7 January 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 (9 January 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.