NSW Seasonal Conditions Summary August 2015

Highlights

  • Rainfall during July was average to above average across most of NSW. Above average rainfall occurred across areas of the north west, Riverina, southern central west, southern tablelands and the south east. Below average rainfall occurred across the lower Hunter, mid-north coast and the south of the northern tablelands.
  • The rainfall and daytime temperature outlooks are near-neutral over most of NSW between August and October. The north east is likely to be drier and the north and east are likely to have warmer daytime temperatures. Overnight temperatures are likely to be warmer.
  • During August, wetter than normal conditions are likely in the south, with a neutral outlook for the rest of NSW. Cooler daytime temperature are likely in the south, warmer in the north east and a neutral outlook in the north. Overnight temperatures are likely to be warmer in central, eastern and northern 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 are likely. Average to warm sea surface temperatures to the north west and west of Australia are a positive influence for potential rainfall, but cooling has occurred to the north.
  • Topsoil moisture levels were maintained across most of NSW. Subsoil moisture levels improved across most of the cropping areas. Run off improved over areas of the central west, central Riverina and the coast, but remained low in other areas.
  • Pasture growth improved across much of inland NSW and the central to north coast but remained low over the tablelands. Bloat has been a problem in some areas. Supplementary feeding is occurring in areas with slow growth and low biomass.
  • Winter crop growth was good in most areas, particularly for early to mid-season sowings. Development of later sown crops has been slow. Yield modelling suggests a good wheat outlook if normal spring rainfall occurs. Forage crops are showing good production, particularly on the tablelands and slopes.

Overview

Rainfall during July was average across most of the state. Above average rainfall occurred across 25 per cent of NSW, covering areas of the Riverina, central, northern and south eastern NSW. Below average rainfall occurred over 6 per cent of NSW, and was confined to areas of the central to mid-north coast, lower Hunter valley, the south of the northern tablelands and the far south west and far north west.

Pasture growth improved across most of northern, central and southern NSW, the Hunter valley and the central, mid-north and north coast. Growth remained stable to low in the south of the central and northern tablelands, over the southern tablelands, Monaro and areas of the south east. In these areas it has been restricted by the cooler temperatures. There was a decline in growth in areas of the far west. Bloat has been an issue in some areas of the central west and north west due to high clover content in pastures and low grass biomass.

Relative to historical records July pasture growth was above average across most of northern and central NSW, and areas of the south. There were some areas of low growth over areas of the northern Riverina and areas of the southern and central tablelands. Relative growth was near average across most of the coast and the south of the far west.

Biomass levels improved across area of central, southern and northern NSW. Biomass remained low across areas of the far west, areas of the north west, the south east, tablelands, upper areas of the southern slopes and areas of the north coast.

Supplementary feeding continued in many areas due to cold weather, reduced pasture growth and limited biomass. It was most common in areas of north western, southern and south western NSW, in tablelands districts (particularly with breeding stock) and on the mid-north to north coast.

Late sowings of wheat and chickpeas continued into late June and early July in areas of the north west. A high proportion of crops in the north west (west of the Newell Highway) have been sown on limited soil moisture and will require good follow up rainfall. Crop growth was good across most of the cropping belt, with the exception of some areas such as the far south west. Early sown crops are generally well advanced and may have a higher risk of frosting. Later sown crops have been slower to develop due to cool temperatures and wetter conditions. Heavy rainfall in some areas has resulted in patchy crop damage from waterlogging, particularly in legume crops. Forage crops continued to produce well on the tablelands and slopes.

Modelling by the Australian Export Grains Innovation Centre (AEGIC) in early August indicated an above-average wheat yield outlook for most of NSW if spring rainfall is normal. However, if the current El Niño event has a greater influence on rainfall during the remainder of August and September, crop yields may not reach their full potential, particularly over areas of southern and central NSW and the western margin of the north west.

Topsoil moisture levels were maintained across most of NSW, but declined slightly in the west and areas of the north east. Levels improved across the Riverina, southern and central tablelands and areas of the central west. Subsoil moisture remained low over areas of the north west, northern central west and far south west, but generally improved across most of the cropping areas. Subsoil moisture remained moderate to high across the tablelands and slopes and high along the coastal strip.

Despite the rainfall during June and July, run off was limited in a number of areas across the state and stock water supplies remain variable. Streamflow analysis over the last twelve months showed an improvement across areas of the central west and central Riverina.Run off remained below average across areas of the north west, the central west, the far south and the western Riverina, as well as the central tablelands and upper areas of the southern slopes. Some localities within these areas have reported run off occurring, but stock water levels are low to near critical in others.

NSW Seasonal Conditions Report – July 2015

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Seasonal outlook

The Bureau of Meteorology rainfall and daytime temperature outlooks are near-neutral over most of NSW between August and October. This means there is a near-equal chance of drier or wetter than normal conditions and for cooler or warmer than normal daytime temperatures. Drier than normal conditions are likely in areas of north eastern and far south eastern NSW. Warmer than normal daytime temperatures are likely across most of the coast, Hunter Valley and northern NSW (including the northern tablelands and the north west). Warmer than normal overnight temperatures are likely across all of NSW.

During August, wetter than normal conditions are likely across much of the southern half of NSW. There is a near-equal chance of drier or wetter than normal conditions for the northern half of NSW, the coast and areas of the south east and western Riverina. Cooler than normal daytime temperatures area likely for areas of the south west, Riverina, the southern half of the central west and the west of the central tablelands. Warmer than normal daytime temperatures are likely in the north east, mid-north coast and far south east. Overnight temperatures are likely to be warmer over the eastern half of NSW and northern NSW.

Of the global climate models surveyed, about half suggest drier than normal conditions across NSW between August and October and also between September and October. The majority suggest conditions over both periods will be warmer than normal. Note that this does not indicate a reduced frost risk.

The pasture growth outlook for August to October suggests generally near average growth for the south to mid-north coast and the Monaro, but below average growth for the tablelands, slopes and plains. Above average growth is suggested for the eastern edge of the rangelands and below average growth for the remainder. Above average growth is suggested for western NSW. Skill levels are moderate to high across most of NSW.The growth outlook is based on a consistently negative SOI in June/July, and a probability of well below average rainfall across much of inland NSW and generally average rainfall across the coast during August to October. Note that as the Bureau of Meteorology's outlook for the same period is for a near-equal probability of above or below average rainfall across the state (except in the north east), pasture growth could be better than indicated in most areas of the state.

El Niño Southern Oscillation (ENSO)

The Pacific Ocean remains in an El Niño event, and this has continued to intensify. Sea surface temperatures in the central Pacific have continued to rise. Global climate models indicate that the El Niño event is likely to persist through spring and summer. 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.

The NOAA Climate Prediction Centre and International Research Institute for Climate and Society in the USA have indicated that (based on their thresholds and indicators) the El Niño event is currently moderate, with models suggesting a strong event is likely through spring and early summer.

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.

The effects of the El Niño event continue to be moderated by average to warm sea surface temperatures to the west and north west of Australia, providing potential sources of moisture for NSW. However, cooling has occurred to the north and is occurring in areas of the north east and north west, which may have reduce potential moisture sources. Additionally, three out of five climate models are suggesting a positive Indian Ocean Dipole event during spring, which is associated with drier than normal conditions.

Warm sea surface temperatures anomalies extend across the central and eastern equatorial Pacific, and strengthened during July in the central areas. The NINO 3 and 3.4 indices (as at 9 August) are more than 1.6°C above normal. In the far east, the sea surface temperatures are more than 1.8°C above normal. Warm sea surface temperatures also extend across the Indian Ocean.

Sub-surface warm temperature anomalies remain across most of the central to eastern equatorial Pacific to a depth of 100-200 m. A cool anomaly present at depth in the west has moved eastwards, cooling sub-surface temperatures below 100m in the eastern-central equatorial Pacific.

Trade winds were reversed (westerly) during July across the western to the east-central equatorial Pacific. During late July-early August, westerly trade winds strengthened east of the International Date Line but were normal in the west.

The SOI is strongly negative at -19.8 (as at 12 August) and has remained negative since late June.Over the month, cloud near the junction of the equator and the International Date Line was above normal, and was low over Indonesia and Papua New Guinea.

Climatic outlook summary

NSW Seasonal Outlook Current outlook Previous outlook
Quarterly Rainfall

Near neutral – neutral
(most of NSW)

Drier
(far south east, north east)

Near neutral - neutral          
(most of NSW)

Drier 
(far south east)

Quarterly Maximum Temperature

Near neutral – neutral
(most of NSW)

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

Near neutral - neutral
(most of NSW)

Warmer
(coast, far south east)

Quarterly Minimum Temperature

Warmer

Warmer
(northern, eastern, central, southern NSW)

Near neutral
(central and southern areas of far west)

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) Neutral - positive Neutral - positive
Southern Annular Mode (SAM/AAO) Slightly positive - near neutral Moderately positive 

Rainfall and temperature

During July, rainfall across the state ranged from 1-203 mm. Falls over most of the state ranged from 10-50 mm. Areas of the northern slopes and tablelands, central NSW, the Riverina and the south east received 50-100 mm. Some areas in the central west, southern slopes, southern tablelands and the south east received between 100-200 mm.

The lowest recordings of 1-10 mm occurred across areas far west, the northern Hunter valley and the mid-north coast. Rainfall was between 10-25 mm across the central third of the far west, far south west, the western Riverina, the south east of the northern tablelands and those areas of the north coast and lower Hunter valley away from the coastal strip.

During July, daytime temperatures were 0.5 °C below average across NSW, with areas of the west and central west having daytime temperatures of 1-2°C below normal. The coastal strip from the central to mid-north coast had near-normal daytime temperatures.Average overnight temperatures were 0.1 °C above average across NSW during July, with temperatures generally 0-1°C below normal across the south and west, but warmer than normal across most of the north west, northern tablelands, north east, Hunter valley and far south east.

Relative rainfall

Relative to historical records, rainfall during July was above average across 25 per cent of the state, average over 68 per cent and below average over 6 per cent.

Areas in the lower Hunter valley, on the central to mid-north coast, the south of the north coast, the south of the northern tablelands and the far south west received below average relative rainfall.

Areas of the north west, the Riverina, southern tablelands, south east, the west of the central tablelands and southern half of the central west received above average rainfall. Some areas of the central west and central-northern Riverina received extremely high relative rainfall. Rainfall was near average across most of the far south, west and north of the State.

Quarterly relative rainfall was above average across 38 per cent of the state, including the far north west and areas of the central west and Riverina, and average across most of the remainder.Half yearly relative rainfall was generally average across the state, but below average in areas of the south.

Soil moisture

Moderate modelled topsoil moisture levels were maintained across most of NSW, but declined slightly in the west and areas of the north east. Levels improved across the Riverina, southern and central tablelands and areas of the central west.

Relative to historical records, topsoil moisture was generally average across the east, south and far west of NSW. It was above average across the north west, central west, central Riverina, the central, northern and eastern areas of the far west and in the far south east. Relative topsoil moisture was low in areas of the lower Hunter valley and the adjacent areas of the mid-north coast.

Modelled subsoil moisture levels improved across the central west, Riverina and areas of the tablelands. They remained high along the coast, but were still limited in areas of the north west and south west.Relative to historical records, subsoil moisture remained below average across areas of the north west, western Riverina, south west and the south of the central tablelands.

Streamflow

Run off improved across areas of the central Riverina and the central west during July. However, in many areas it was variable. Run off was average to above average across the coast, south east and areas of the far west. In areas of the north west, central tablelands and far south, run off was limited and farm water supplies range from moderate to low.

The Bureau of Meteorology's streamflow forecast indicates low streamflows are likely across most southern NSW monitoring stations during August to October, and near-median flows at central NSW monitoring stations and in areas of the north. High streamflows are likely in some areas of NSW, mainly in coastal locations. Low streamflows were recorded at a number of locations during July .

Relative pasture growth and biomass

Relative to historical records, AussieGRASS modelled pasture growth for July remained high across the most of northern and central NSW, and improved across the far south and the western and central Riverina. Relative growth remained below average across areas of the southern and central tablelands, but generally average across the far west, coast and south east.

Relative growth for July was average over 40 per cent of NSW and above average over 46 per cent.

Other pasture growth models indicated well above average growth for temperate pastures across areas of the north west and far west. Growth for the coast was generally average. It was below average in the south east of the central west, the western Riverina and across areas of the far south, the northern, southern and central tablelands and the Monaro.

Over the three months to July, AussieGRASS relative growth was generally above average across northern and central NSW and in areas of the south and average across the south west and coast. It was below average across the southern tablelands and areas of the western and northern Riverina, the Monaro and areas of the far south.

During July, relative biomass levels improved slightly. They remained high across areas of the central west and central tablelands, the north west of the northern tablelands, the northern slopes and areas of the far south and far west. Over most of the south and east of the state, relative biomass levels were average. Relative biomass generally improved over areas of the north west and northern and western Riverina, but still remained low in some areas.

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 11-12 August 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 (11-12 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.