NSW Seasonal Conditions Summary November 2015

Highlights

  • Rainfall during October was below average across much of western, southern and south eastern NSW, as well as areas of the north. Storm rainfall occurred in early November across most cropping areas, the tablelands and coast.
  • The rainfall outlook for November to January indicates a near-neutral outlook for most of NSW, with drier than normal conditions likely across south eastern NSW. Warmer temperatures are likely across most of the state.
  • During November, there is a near-neutral rainfall outlook for most of NSW, with drier conditions likely across the south east and areas of the north west. Warmer than normal daytime and overnight temperatures are likely.
  • The El Niño has continued to intensify, with dry conditions during October. Warmer sea temperatures to the west of Australia have once again moderated its effects on rainfall during early November.
  • Topsoil moisture declined across NSW, but was partly replenished by the early November rainfall.
  • Pasture growth declined across the western half of NSW during October. Growth was maintained in areas of the Riverina, and across the south west slopes, tablelands and coast. 
  • Lack of rainfall and hot weather during October reduced winter crop yield prospects. Some crops on the far northern and southern margins of the cropping belt were abandoned. Harvest commenced early in the northern and central areas. The November storms and rainfall caused damage to unharvested winter crops, particularly in the western areas, but the rainfall will benefit grain fill in crops in the east.
  • Dryland summer crop sowings in northern and central NSW were delayed due to lack of topsoil moisture, but the recent rainfall will encourage further sowings and crop establishment. Water allocations in central and southern areas have favoured sowings of cotton over other crops

Overview

Rainfall during October was below average across nearly 50 per cent of the state. Areas of below average rainfall occurred across areas of the south, south east, Riverina, tablelands, north west and far west. The remainder of the state including most of the coast, central west and areas of the north west and west received average rainfall

Pasture growth declined across the western half of NSW during October, particularly across the far west and areas of the north west, central west, central Riverina and far south. Growth was maintained in areas of the eastern and western Riverina, the south west slopes, tablelands and adjacent slopes, the south east and the coast.

Relative to historical records, pasture growth was below average across most of inland NSW and average along the coast.

Biomass levels declined across areas of the far west, central west, north west and the central to north coast. Levels remained low in the tablelands, but remained relatively high in areas of the south, south west slopes and Riverina.

Haymaking continued in many regions through October, although rainfall in early November is likely to have caused reductions in quality where haymaking was not completed.

Recent rainfall will benefit the growth of summer-growing pastures in the north and west, and perennial pastures across the slopes, tablelands and coast.

Lack of rainfall and dry, hot conditions October reduced winter crop yield prospects in the western and central areas of the cropping belt and hastened crop maturity. Some crops in the far north west and south west were abandoned, with cereal crops being grazed out or cut for hay. Harvest commenced early in the north west.

Storm events and rainfall between the end of October and early November caused damage to and delayed harvest of mature cereal crops. The rainfall and winds caused winter crops to lodge and put grain at risk of being downgraded. In the western areas of the cropping belt, particularly in the north west, much of the canola, faba beans and barley had already been harvested before the rainfall, but the wheat harvest was still under way. Along the western edge of the central west, harvesting of barley and canola was under way, with the wheat harvest just commencing.

In the eastern areas of the central west, Riverina and south the cereal crops are still in mid-late grain fill. In these areas, the rainfall may go some way to compensating for effects on yields from the hot, dry October and some frosting in late September.

A return to dry and warm conditions during mid-November across the cropping areas would be welcomed, to aid in preventing further crop damage and losses in the quality of cut hay, and to allow harvesting to continue.

Much of the dryland summer crop sowing in northern and central areas was delayed due to lack of topsoil moisture during October. The recent rainfall has benefitted establishing and sown crops and will stimulate further sowings, and will benefit soil moisture storage on fallowed areas. Water costs and allocations in southern and central NSW have favoured cotton over other irrigated crops, and allocations have also been used to finish winter crops.

Modelled topsoil moisture declined to low levels across the majority of NSW during October. Rainfall in early November replenished levels in areas of the north west, central west, Riverina, tablelands and coast.

Modelled subsoil moisture levels declined slightly in areas of the northern slopes, central west, western Riverina and the south west. Rainfall during early November has been sufficient to increase subsoil moisture reserves somewhat.

The dry period from September through October and the high temperatures in October meant stock water supplies declined, particularly across the far west and plains. However, storm rainfall across much of the eastern half of NSW during early November has allowed stock water supplies to replenish in many areas. However, supplies are still marginal in some districts.

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Seasonal outlook

The Bureau of Meteorology's rainfall outlook for November to January indicates that drier than normal conditions are likely for areas of south eastern NSW including areas of the south west slopes, southern and central tablelands, Sydney basin, Monaro, Illawarra and south coast. Wetter than normal conditions are likely in the far north east, including areas of the north coast and northern tablelands. There is a near-neutral outlook for most of NSW during the period. This means there is a near-equal chance of drier or wetter than normal conditions. There is a high probability of warmer than normal daytime temperatures across the majority of NSW for the period, with a near-neutral outlook for areas of northern and western NSW. Overnight temperatures across NSW during the period are likely to be warmer than normal, except in the far south west.

During November, there is a near-neutral rainfall outlook for most of NSW (that is, a near-equal probability of drier or wetter than normal conditions). Drier than normal conditions are likely in areas of the south and south east, and in an area of the north west. Warmer than normal daytime and overnight temperatures are likely across all of NSW.

Of the global climate models surveyed in late October, about 55 per cent suggest near-neutral conditions are likely across most areas of NSW between November and January (that is, a near-equal probability of drier or wetter than normal conditions). About 18 per cent suggest drier than normal conditions and 27% wetter than normal conditions. Nearly 80 per cent of models suggest conditions will be warmer than normal. 

The pasture growth outlook for November to January suggests generally below average growth is likely across most of the north west, north western central west and south of NSW. Average to slightly above average growth is suggested for most areas of the tablelands and the far south west. Average growth is suggested for some areas of the slopes. Generally below average growth is suggested for the coast. Skill levels for the outlook are moderate to high across eastern NSW, including the tablelands, but are moderate to low for much of central NSW and low for much of the west.

The rainfall outlook that the growth outlook is based upon suggests below average rainfall for much of south eastern and coastal NSW and an area of central NSW. The outlook is based upon a consistently negative SOI during September to October. It suggests a near-neutral rainfall outlook for areas of southern, south western and north western NSW. As such, it is only partly consistent with the rainfall outlook from the Bureau of Meteorology, and growth across NSW may be underestimated.

El Niño Southern Oscillation (ENSO)

The Pacific Ocean is in a strong El Niño event, which continues to intensify with sea surface temperatures in the central equatorial Pacific being over two degrees above average. A positive Indian Ocean Dipole (IOD) event is still under way, although is expected to return to neutral during November or early December with the onset of the monsoon.

Most modelling suggests the El Niño event will reach its peak soon and is likely to end in autumn 2016. The effects of the El Niño and IOD events are currently being offset by warm sea surface temperatures in the Indian Ocean to the west and south of Western Australia and the presence of an upper level low pressure cell to the north west of Western Australia.

During summer, an El Niño event increases the likelihood of higher temperatures over NSW. An increased number of heatwaves are also likely during November to March, particularly during strong El Niño events and when soil moisture levels are lower than normal.

The effects of an El Niño event on rainfall tend to decrease during summer. During the past 12 strongest El Niño events, the Bureau of Meteorology's analysis indicates rainfall across the state (as a whole) was lower than normal in about 25-33 per cent of cases and near average or above in about 66-75 per cent of cases. However, these probabilities vary from region to region across the state and every El Niño event is different.

Recent information suggests the likelihood of a switch from the current El Niño event into a La Niña in 2016 is declining. The most likely situation is now a return to neutral conditions in 2016.

The SOI and equatorial Pacific sea temperatures, trade wind and cloud conditions remain consistent with an El Niño event. Warm sea surface temperature anomalies extend across the central and eastern equatorial Pacific. Sea surface temperatures recently rose in the west, although the anomalies are weak. Sub-surface warm temperature anomalies remain across most of the central to eastern equatorial Pacific to a depth of 100-200m. A cool anomaly exists at depth in the west and western-central areas. This pattern of warm and cool anomalies is consistent with an El Niño event.

Sea surface temperatures to the north of Australia remain cool. This may reduce sources of convection and moisture. Cooler than normal sea surface temperatures near Sumatra during September and early October (in comparison to the western Indian Ocean) resulted in the positive IOD event occurring. The sea surface temperatures near Sumatra increased slightly during late October and early November, and with the influence of the monsoon conditions in this area should return to normal.Sea surface temperatures remain warm to the west and south west of Western Australia and have acted to moderate the effects of the El Niño and positive IOD.

Climatic outlook summary

NSW Seasonal Outlook Current outlook Previous outlook

Quarterly Rainfall

Drier
(south east, areas of south & central NSW, south to central coast)

Near neutral
(most of NSW)

Wetter
(far north east)

Drier
(south eastern, southern and central NSW, south to mid-north coast, Hunter valley and southern areas of the northern tablelands and northern slopes)

Near neutral – neutral
(northern and western NSW)

Quarterly Maximum Temperature

Near neutral
(areas of northern & far western NSW)

Warmer
(eastern, central & areas of southern & western NSW)

Warmer

Quarterly Minimum Temperature

Warmer

Warmer

El Niño Southern Oscillation (ENSO)

ENSO (overall)

El Niño

El Niño

BoM ENSO Tracker Status

El Niño

El Niño

SOI

Moderately to strongly negative

Strongly negative

Pacific Ocean (NINO3.4)

Very warm
(Above El Niño thresholds)

Very warm
(Above El Niño thresholds)

Indian Ocean (IOD)

Positive
(trending to neutral during November/December)

Positive
(trending to neutral during November)

Southern Annular Mode (SAM/AAO)

Weakly positive – near neutral

Near neutral

Rainfall and temperature

During October, rainfall across the state ranged from 0-79 mm. Above average rainfall was restricted to isolated areas of the north east and the southern central west.

Falls over most of the state ranged from 10-50 mm. Falls of less than 10 mm occurred across areas of far western NSW, the far north west and the south west. Falls of less than 10 mm also occurred in the western Riverina. Most of the north west, central west, south and south east received falls of 10-50 mm. Rainfall of 50 mm or more was mostly restricted to areas of the central and mid-north to north coast, the northern and north eastern areas of the northern tablelands, an area of the eastern central west and the northern central tablelands and isolated areas of the south east.

Significant storm rainfall occurred across much of the state from the end of October through the first week of November, with most of the state receiving more than 15mm and many areas up to 100mm.

A significant heatwave occurred early in the month, with temperatures remaining high over most of the month and the state having its warmest October on record.

Daytime temperatures were well above average for the month, with most of the state having temperatures of 4-6 degrees above average. Overnight temperatures were warmer than normal, with temperatures of 2-4 degrees above average across most of the state except the north east.

Relative rainfall

Relative to historical records, rainfall during October was below average across much of western, southern and south eastern NSW, as well as areas of the north west, northern tablelands, Hunter valley and the central areas of the north coast.

Isolated areas of above average relative rainfall occurred in the south of the central west and northern and southern areas of the north coast. Relative rainfall was near average across the east of the far west, western areas of the north west, the central west and much of the coastal strip.

Quarterly relative rainfall was below average across much of northern NSW, the tablelands, the upper Hunter valley and the far south. Above average relative rainfall was mostly limited to the Illawarra. Most other coastal areas had near-average quarterly relative rainfall, as did the southern areas of the central west, the central Riverina and the central areas of the far west.

Soil moisture

Modelled topsoil moisture levels declined across most of NSW, during October, being at low levels across all but areas of coastal NSW. Relative to historical records, topsoil moisture was well below average to extremely low across most of inland NSW. It was average across most of the coast and areas of the far west.

Modelled subsoil moisture levels declined slightly in areas of the northern slopes, central west, western Riverina and the south west. Relative to historical records, subsoil moisture remained below average across areas of the north west, northern central west, far south and far western Riverina, as well as areas of the central and northern tablelands.

Streamflow

Yearly run off estimates were similar to the period to September, but remained variable in many areas. Run off was low in the north of the central tablelands and the central west, as well as the western areas of the central west, north west and the far south. Areas of low run off also occurred in the upper Hunter valley and central areas of the northern tablelands. Run off was high over areas of far western NSW, the south east and areas of the central coast and lower Hunter valley.

Storm rainfall in the first week of November has alleviated stock water supplies in many areas, including areas of the north west, central west and the Riverina.

The Bureau of Meteorology's streamflow forecast indicates generally low streamflows are likely across most inland southern NSW monitoring stations during November to January, with some tending towards near-median (particularly in the south east).

Relative pasture growth and biomass

Relative to historical records, AussieGRASS modelled pasture growth for October was below average across almost half of the state, and mostly average for the remainder. Below average relative growth occurred across most of the north west, central west, upper Hunter valley, central Riverina, far south, tablelands and much of the far west. Relative growth was generally average across the coast and areas of the western Riverina. It was above average over areas of the far south east.

Other pasture growth models suggested a similar growth pattern, with below average relative growth across most of far western, northern, north western, and southern NSW. Most of the tablelands, the north of the central west and the upper Hunter valley also showed below average relative growth, as did an area on the north coast around Grafton. For these models, relative growth was generally average along the coast, southern central west, the north of the northern tablelands and average to above average in areas of the far south east.

Over the quarter, AussieGRASS relative growth was generally average across the state. Below average growth occurred across the south west slopes, the southern and central tablelands and areas of the far north west, northern tablelands and northern central west. Above average growth occurred across areas of the west and the far south east. 

During October, relative biomass levels declined in some areas, although most of the state remained relatively static. Levels declined across the upper Hunter valley and the northern tablelands, and in particular across areas of the far south, south west slopes, central and southern tablelands. Relative biomass levels were above average across areas of the far south east and areas of the central to north coast

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.

Acknowledgements

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 November 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 November 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.