NSW Seasonal Conditions Summary December 2015

Highlights

  • Good rainfall occurred in early November across most of NSW, but conditions since have been generally dry and warm.
  • The rainfall outlook for December to February indicates a near-neutral outlook for most of NSW, with wetter than normal conditions likely in the north east. The temperature outlook is also near-neutral for much of NSW, but for warmer than normal conditions in the east and north west.
  • During December, there is a near-neutral rainfall outlook for most of NSW, with wetter conditions likely in the north east. The daytime temperature outlook is near-neutral, but warmer for the west and south. Overnight temperatures are likely to be warmer, except in the north east.
  • The El Niño event may have peaked, but is likely to continue into autumn. Historically, its effects on rainfall across NSW decline during summer.
  • Topsoil moisture was partly replenished by the early November rainfall, but subsoil moisture declined slightly.
  • Pasture growth improved across most of NSW, although hay yields were lower than expected.
  • The November storms caused damage to mature, unharvested winter crops and delayed harvest. Winter crop yields have been variable, with early-mid season and irrigated sowings generally performing the best. Yields of late sown crops were disappointing in some areas.
  • Reduced areas have been sown to summer crops in central and southern NSW. Establishment of early sown summer crops has been rapid due to the rainfall and warm temperatures. In the south, the cost of water and reduced allocations have reduced the rice area in favour of cotton.

Overview

Rainfall during November was above average across 70 per cent of the state. Above average rainfall occurred across much of the western, southern and central areas as well as much of coastal NSW. There were limited areas of below average rainfall in the north west. The remainder of the state received near-average rainfall, covering areas of the far west, north west, much of the northern and central tablelands and the southern highlands.

Pasture growth improved across most of NSW during November. Growth improved in the western half of NSW from low to moderate levels, and in the eastern half of NSW from moderate to high levels.

Relative to historical records, November pasture growth was average to above average across most of NSW.

Biomass levels were maintained during November in the west and improved in the east, particularly across the slopes, tablelands, Monaro and coast.

Storms and heavy rainfall in early November affected winter crop harvesting. In the western areas of the cropping belt, particularly in the north west, many of the barley, canola and faba bean crops had already been harvested before the storms. However, the wheat harvest was underway or had recently commenced in these areas when the storms occurred. Yields and grain quality were affected. In the south, heavy early sown and irrigated crops lodged, which slowed harvest. Late sown crops performed poorly in areas of the north west and south west. In the central and eastern areas of the cropping belt yields generally varied from below average to close to average, with early sown crops performing best and some reaching above average yields.

The area sown to summer crops is lower than normal in southern and central NSW and in the western half of the north west. Early sown crops benefitted from the November rainfall, but follow up falls are needed. High temperatures have enhanced crop development. Lack of water allocations and the high cost of water favoured a shift from rice to cotton in the south.

The November rainfall has reduced the quality of standing dry feed in areas where pastures had hayed off in October. Haymaking was also delayed, but was favoured by a return to dry, warm weather. Quantities were lower than expected and some loss of quality occurred. Perennial pastures responded to the rainfall and performed well on the tablelands and coast. Summer growing perennials responded well in the west. Warm temperatures and lack of follow up rainfall has resulted in rapid haying off.

Modelled topsoil moisture improved across the state during November, particularly across the coast, tablelands, slopes, central west and eastern Riverina. Topsoil moisture has declined to low levels since due to warm temperatures and lack of follow up rainfall, except in areas of the north east.

Modelled subsoil moisture levels declined slightly in most areas, although they remained moderate to high over most of the coast and south east, and moderate across most of the tablelands and slopes.Stock water supplies improved in many areas, but still remain variable. Supplies are still low in areas of the central and northern tablelands, upper Hunter, central west and north west.

NSW Seasonal Conditions Report – December 2015

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Seasonal outlook

The Bureau of Meteorology's rainfall outlook for January to March is similar to that for December to January and is near-neutral for most of NSW. This means there is a near-equal chance of drier or wetter than normal conditions. Wetter than normal conditions are likely across far north eastern NSW. Drier than normal conditions are likely for an area of the south east, extending across the southern tablelands, Monaro and south west slopes. There a near-neutral outlook for daytime temperatures across the far west and areas of the western Riverina and southern NSW for the period. Warmer than normal daytime temperatures are likely most of eastern NSW including areas of the north west, central west, south west slopes, tablelands and coast. Cooler than normal daytime temperatures are likely in the far south west. Warmer than normal overnight temperatures are likely across most of the coast, tablelands, Hunter valley and north west. Cooler than normal overnight temperatures are likely in areas of the far west, south west and western Riverina.

During December, there is a near-neutral rainfall outlook for most of NSW (that is, a near-equal probability of drier or wetter than normal conditions). Wetter than normal conditions are likely in areas of the north east including the north coast, northern tablelands and areas of the Hunter valley and north west. There a near-neutral outlook for daytime temperatures across most of NSW for December. Warmer than normal conditions are likely across the far west, south west, south and far south east. Cooler than normal daytime temperatures are likely in areas of the north east. Overnight temperatures are likely to be warmer than normal across western, southern and much of central NSW. There a near-neutral outlook for overnight temperatures for the period across the remainder of NSW.

During January, there is a near-neutral rainfall outlook for most of NSW. Drier than normal conditions are likely in the south east, including the south coast, southern tablelands, Monaro and Sydney basin and areas of the south west slopes, central tablelands and southern Hunter valley. Warmer than normal daytime temperatures are likely across the eastern half of NSW, including the coast, tablelands, Monaro, central west, north west and eastern-central Riverina. Cooler than normal conditions are likely in the far south west. Warmer than normal overnight temperatures are likely in the east, including most of the coast, tablelands, north-eastern central west and the north west. Cooler than normal conditions are likely across areas of western and southern NSW.

The global climate models surveyed are equally split between a drier than normal, wetter than normal and near-neutral outlook for most of NSW between December and February. For January to March, 11 per cent of models indicate a wetter than normal outlook, 33 per cent drier and 56 per cent near-neutral.The pasture growth outlook for December to February suggests generally below average growth is likely across most of the state. Above average growth is suggested for most areas of the tablelands (except the eastern half of the Northern Tablelands) and areas of the far south west and south west slopes. Average growth is suggested for the far south and the southern areas of the Riverina. Generally below average growth is suggested for the coast.

The skill levels for this outlook are generally low across NSW, but are moderate to high over eastern NSW, the tablelands and areas of the central west. The rainfall prediction that the growth outlook is based upon suggests a near-neutral outlook for much of NSW, with drier than normal conditions likely for areas of the central west, south coast, central to mid-north coast and areas of the far west. The outlook was based upon rapidly rising SOI during October to November. The rainfall outlook is reasonably consistent with that of the Bureau of Meteorology, however the skill levels indicate the pasture growth outlook should be regarded with some caution.

El Niño Southern Oscillation (ENSO)

The Pacific Ocean remains in a strong El Niño event, although there is some indication it may have peaked and is starting to decline. The positive Indian Ocean Dipole (IOD) event ended in mid-November with a rapid return to neutral conditions.

Most modelling continues to suggest that the El Niño event is likely to continue until late autumn or early winter 2016. Recent information suggests that a return to neutral conditions is most likely in 2016, with a La Niña event less likely.

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 shows that 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.

The equatorial Pacific sea temperatures, trade wind and cloud conditions remain consistent with an El Niño event. The SOI recently increased to neutral levels before falling again, as it tends to become more variable during the monsoon season.Warm sea surface temperature anomalies extend across the central and eastern equatorial Pacific. Sea surface temperatures recently returned to near-normal in the equatorial Pacific west of the International Date Line and began to warm to the north of Australia. Sub-surface warm temperature anomalies remain across most of the central to eastern equatorial Pacific. A cool anomaly exists in the west, has strengthened and has moved eastwards at depth into the central equatorial Pacific. This with other indicators may signal the start of the decay of the El Niño event.

Climatic outlook summary

NSW Seasonal Outlook Current outlook Previous outlook

Quarterly Rainfall

Near neutral
(most of NSW)

Wetter
(far north east)

Drier
(areas of the south east, Monaro, southern tablelands and south-west slopes)

Near neutral
(most of NSW)

Wetter
(north east, Northern Tablelands, areas of northern slopes and plains and areas of mid-north coast)

Drier
(limited areas of south east)

Quarterly Maximum Temperature

Warmer
(north west, central west, eastern Riverina, tablelands, Monaro and coast)

Near neutral
(most of western NSW, western Riverina and far south)

Cooler
(far south west)

Near neutral
(most of NSW)

Warmer
(far north west, south east, central tablelands, areas of Hunter valley and mid-north coast)

Cooler
(far south west)

Quarterly Minimum Temperature

Warmer
(north west, coast, Hunter valley, north western central west and tablelands)

Near neutral
(far north west, south western central west, eastern Riverina, and south west slopes)

Cooler
(far west)

Near neutral
(most of NSW)

Warmer
(far north west, coastal strip, areas of south east, central tablelands, Hunter valley)

Cooler
(areas of far south west)

El Niño Southern Oscillation (ENSO)

ENSO (overall)

El Niño

El Niño

BoM ENSO Tracker Status

El Niño

El Niño

SOI

Variable, currently moderately negative

Moderately to strongly negative

Pacific Ocean (NINO3.4)

Very warm
(above El Niño thresholds)

Very warm
(above El Niño thresholds)

Indian Ocean (IOD)

Neutral

Positive
(trending to neutral during November/December)

Southern Annular Mode (SAM/AAO)

Neutral-moderately negative

Weakly positive – near neutral

Rainfall and temperature

During November, rainfall across the state ranged from 6-422 mm, with most of the state receiving 25-100 mm. Falls of less than 25 mm occurred across areas of far western NSW and areas of the north west near the Queensland border. Falls of 100-200 mm occurred across areas of the coast, Hunter valley, northern tablelands and south west slope, with isolated areas receiving falls of up to 300 mm or more. Most of the north west, central west, Riverina, Monaro and south received falls of 50-100 mm.

Most rainfall occurred during the first two weeks of the month. Significant storm rainfall occurred across much of the state throughout the first week of November.Temperatures were above average for the month, with most of the state having maximum temperatures of 2-3 degrees above average and overnight temperatures of 1-3 degrees above average. This was largely due to two periods in mid-late November when hot north-westerly winds occurred.

Relative rainfall

Relative to historical records, rainfall during November was above average across much of southern, western and central NSW and from the central to north coast. Rainfall was average across much of the north west and tablelands. Isolated areas of below average rainfall occurred in the north west, northern tablelands and southern highlands.Quarterly relative rainfall was average across most of NSW, but was below average across areas of the north west, northern tablelands, far south and south west, the southern tablelands and highlands, the eastern Riverina and the alpine areas. Above average rainfall occurred across areas of the mid-north and far north coast, and isolated areas of western and south eastern NSW.

Soil moisture

Average modelled topsoil moisture levels improved across eastern NSW during November, and also in areas of central, north western and southern NSW. It has declined since across most of NSW due to the warm, dry conditions in mid-late November and early December. Relative to historical records, topsoil moisture was generally average to well above average across most of NSW, but is now below average.Modelled subsoil moisture levels declined slightly across in most areas but remained moderate to high across most of the coast, south east and Riverina. Levels were moderate across the tablelands and slopes, but have declined somewhat since. Relative to historical records, subsoil moisture remained below average across areas of the north west, northern central west, far south and areas of the central and northern tablelands.

Streamflow

Yearly run off estimates were similar to the period to October, but remained variable in many areas. Run off was low in the north of the central tablelands, as well as the western areas of the central west, north west and areas of 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, lower Hunter valley and central Riverina.The Bureau of Meteorology's streamflow forecast

indicates generally near-median streamflows are likely across most inland southern NSW monitoring stations during December to February. Some stations are tending towards low streamflows in the far south. In the south east, near-median to high streamflows are likely. Low flows are likely in the north east.

Relative pasture growth and biomass

Relative to historical records, AussieGRASS modelled pasture growth for November was average to above average across most of NSW. Below average relative growth occurred across limited areas of the north west and far south. Growth was above average across areas of the north east, Hunter valley, tablelands, south east, the central west and the eastern and central Riverina.

Other pasture growth models suggested a similar growth pattern, with below average relative growth across the northern edge of the north west. Most of the Riverina, far south and south east had above average growth, as did areas of the central west, north east, central tablelands, Hunter valley and Sydney basin. The remainder of NSW had generally average relative growth.

Over the quarter, AussieGRASS relative growth was generally average across the state. Below average growth occurred across areas of the north west, central northern tablelands, northern central west, eastern Riverina and southern tablelands. Above average growth occurred across some western areas, the far south east, the lower Hunter and much of the north coast.During November, relative biomass levels were generally average across NSW. They improved along the coast, tablelands, Hunter valley and eastern Riverina. Levels were low in areas of the far south, north west and far north west. Relative biomass levels were above average across areas of the far south east, the central to north coast and the eastern Riverina.

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 17 December 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 (17 December 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.