NSW Seasonal Conditions Summary August 2016

Highlights

  • Conditions in central, southern and south eastern NSW were wetter than normal, with the remainder of NSW experiencing generally near-average rainfall.
  • The rainfall outlook for August to October indicates wetter than normal conditions are likely across NSW. Cooler daytime temperatures are likely for most of NSW, except the far west. There is a near-equal chance of cooler or warmer than normal overnight temperatures across most of NSW, with warmer temperatures likely in the far west and far south east and cooler temperatures likely for areas of the north west.
  • During August, wetter than normal conditions are likely across most of NSW except areas of the west. Cooler than normal daytime temperatures are likely across most of NSW except the far west, where there is a near-equal chance of cooler or warmer than normal daytime temperatures. Warmer than normal overnight temperatures are likely for most of NSW. There is a near-equal chance of cooler or warmer than normal overnight temperatures across areas of the west, central west, north west and northern Riverina.
  • The Pacific Ocean remains in an ENSO-neutral state. A negative IOD event is occurring, contributing to a greater likelihood of wetter than normal conditions and cooler daytime temperatures. Global climate models suggest a short-lived borderline or weak La Niña event remains possible during spring, but the likelihood has decreased. The Bureau of Meteorology’s ENSO outlook status remains at La Niña watch.
  • Topsoil moisture levels remained high across NSW during July. Subsoil moisture improved, particularly in southern and central NSW.
  • Pasture growth was restricted in some areas by wet conditions, but growth was maintained or improved across much of NSW. Stock condition remains relatively good, but has slipped in some areas. Supplementary feeding has been necessary to maintain condition and reduce the risk of nutritional disorders in many areas.
  • Early sown winter crops are performing reasonably well, despite the wet conditions. Trafficability problems continue to delay disease, weed and insect pest control and topdressing. Late sown crops have suffered from waterlogging and inundation in low lying areas and crop damage has resulted.

Overview

July was wetter than normal for much of central and southern NSW. The central and southern tablelands and much of the central west, Riverina, far south and the Monaro were wetter than normal, as well as areas of the Sydney basin, Illawarra, upper Hunter valley and far west. These areas of the state received rainfall that was generally above 125 per cent of average. Rainfall across the remainder of NSW was near-average, although it was slightly below average over areas of the north coast and north west.

Despite wet conditions restricting pasture growth in some areas, modelled growth was maintained or improved across much of the state. However, it is likely that this may be an overestimate due to waterlogging not being taken fully into account. Growth improved across areas of the coast, north west, central west, Riverina and far south. Growth was maintained across the far west, and improved across the tablelands and south east. Some areas of the coast and tablelands experienced restricted growth.

Relative to historical records, July pasture growth was well above average across inland NSW. It was near-average across most of the coast and the Hunter valley. Other pasture growth models indicated well above average to extremely high relative pasture growth across most of NSW.

Pasture biomass levels remained low in areas of the tablelands, south east and far north west, but improved across most of the far west, north west, central west Riverina and far south. Some improvements also occurred across the central to north coast. Relative to historical records, biomass was generally average to above average across most of the state.

Stock condition remains reasonably good, with supplementary feeding continuing in many areas due to increased energy requirements, the high moisture content of pastures and dual purpose crops and the likelihood of nutritional disorders. Stock health issues such as grass tetany, pregnancy toxaemia, hypocalcaemia, foot scald and bloat have been occurring, and an increase in worm burdens.

Early sown winter crops continued to perform well, although wet conditions have slowed growth. Waterlogging and inundation have caused widespread retarded growth, damage and crop loss in low lying or poorly drained areas and on heavier soils. Areas of particular damage have occurred in the Riverina, central west and north west. Late sown crops have been worst affected. In some localities where sowing or resowing of winter crops could not be completed, growers are now considering planting dryland summer crops later in the year.

The conditions have made topdressing and weed, insect pest and disease control difficult, with aerial application the only option in many areas. Topdressing has also been hampered by limited urea supplies. There has been a relatively high incidence of insect pests and diseases in winter crops in some areas. Grazing of dual purpose crops has been difficult. Growth remained slow during July due to the wet, cold and cloudy conditions, particularly in southern and central areas.

Topsoil moisture remained at high levels across most of NSW during July, except over some areas of the far west. By the end of the month, some drying of topsoils had occurred in areas of the north, far west, far north coast and mid-north coast. Relative to historical records, topsoil moisture remained above average to extremely high across most of inland NSW during July, with areas of the far north and mid north coast being below average.

Subsoil moisture levels continued to improve during July, particularly across areas of southern, central and south eastern NSW. Relative to historical records, subsoil moisture in these areas and areas of western NSW was well above average to extremely high. Levels across the remainder of NSW were generally average, with some areas being below average across the mid-north to north coast.

Significant run off occurred during July, particularly in areas of central and southern NSW and areas of the south east. Significant run off occurred across the northern tablelands and slopes, the far west and upper Hunter valley. To the end of July, yearly run off was above average in most of these areas, although low run off occurred across other areas of the north west, northern tablelands and mid-north to north coast.

NSW Seasonal Conditions Report – August 2016

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Seasonal outlook

The Bureau of Meteorology’s rainfall outlook for August to October (see table) indicates that wetter than normal conditions are likely across NSW. Cooler than normal daytime temperatures are likely for most of NSW. There is a near-equal chance of cooler or warmer than normal daytime temperatures across the far west, far south east and an area of the mid-north coast. There is a near-equal chance of cooler or warmer than normal overnight temperatures across most of NSW. Overnight temperatures are likely to be warmer than normal over the far west and the far south east, and cooler than normal across areas of the north west.

During August, wetter than normal conditions are likely across most of NSW with a near-equal change of wetter or drier than normal conditions in areas of the far west. Daytime temperatures are likely to be cooler than normal across most of NSW. There is a near-equal chance of cooler or warmer than normal daytime temperatures across the far west and in the far south east. Warmer than normal overnight temperatures are likely across much of NSW, with a near-equal chance of cooler or warmer than normal conditions across areas of the north west, west, central west and northern Riverina.

The NOAA Climate Forecast System (CFS) rainfall outlook for August to October is near-neutral for most of NSW, but indicates wetter than normal conditions are likely for areas of southern and south eastern NSW, including the central to south coast. The overall temperature outlook is near-neutral, with cooler than normal conditions likely for areas of the far south west, southern and central NSW.

For August, the CFS rainfall outlook is near-neutral for most of NSW, but indicates wetter than normal conditions are likely for areas of southern and south eastern NSW. There is a near-neutral temperature outlook for most of NSW.

A survey of the major climate models in late July indicated most favour a wetter than normal rainfall outlook for August to October, with the remainder favouring a near-equal chance of drier or wetter than normal conditions. The majority indicated that warmer than normal conditions are likely for the period.

Overall NSW outlook -

major climate models

Rainfall Outlook

(number of models)

Temperature Outlook

(number of models)

Period

Generally wetter

Generally

near-neutral

Generally

drier

Generally warmer

Generally

near-neutral

Generally

cooler

August –  October

8

5

0

5

3

4

September – November

7

2

1

4

3

3

The AussieGRASS pasture growth outlook for August to October suggests that well above average growth is likely for most of western NSW. Above average growth is likely for areas of the central west, south and northern tablelands. Above average growth is also suggested for areas of the Monaro, the southern and central tablelands, the Sydney basin and the far north coast. Generally below average growth is suggested for areas of the Riverina and western plains, with near-average growth for the remainder of NSW.

The seasonal rainfall prediction that the growth outlook is based upon is for near-average rainfall for most of NSW. This was based on a near-zero SOI phase during June and July. The Bureau of Meteorology’s rainfall outlook is different, suggesting wetter than normal conditions are likely. The pasture growth outlook has moderate to high accuracy for most of the state. Due to the differences between the rainfall outlooks, the growth outlook may be an underestimate in some areas.

El Niño Southern Oscillation (ENSO)

The Pacific Ocean remains in an ENSO-neutral state. Sea surface temperatures are near-average to slightly below average in the eastern and central equatorial Pacific and above average in the west.

A negative Indian Ocean Dipole (IOD) event is occurring, has has weakened since July. The event is expected to continue into spring. This means there is greater likelihood of above-average rainfall and cooler daytime temperatures for south-eastern Australia during winter and spring.

A cool subsurface temperature anomaly extends across the equatorial Pacific from 100-200 m in depth in the west to the surface across the central to the eastern equatorial Pacific. It has weakened since May, particularly in the east. Atmospheric indicators (including the SOI, Pacific trade winds and central Pacific cloud conditions) remain at near-normal or neutral levels.

Many global climate models suggest a borderline or weak La Niña event is possible during early spring, although the likelihood has fallen since May-June. If such an event occurs, it is likely to be short-lived. The Bureau of Meteorology’s ENSO outlook status is at La Niña watch, as is that of the CPC/IRI.

Both La Niña and negative IOD events increase the chances of above-average rainfall across NSW during winter and spring.

Warm sea surface temperatures exist to the north, east, north east and north west of the continent and across much of the Indian Ocean. Cloud remains high over areas of western Indonesia, particularly near Sumatra. These areas remain potential sources of moisture for winter and spring rainfall. The Indian Ocean remains cool along the north east coast of Africa and warm near Sumatra, consistent with a negative IOD event. The sub-tropical ridge is somewhat further north than normal and the southern annular mode is moderately to strongly negative. These are positive indicators for winter rainfall.

Climatic outlook summary

NSW Seasonal Outlook (BoM)

Current outlook

Previous outlook

Quarterly Rainfall

Wetter

Wetter

Quarterly Maximum Temperature

Cooler

(most of NSW)

Near neutral

(areas of the far west, far south east and mid-north coast)

Cooler

Quarterly Minimum Temperature

Near neutral

(most of NSW)

Warmer

(areas of the far west and far south east)

Cooler

(areas of the north west and central west)

Cooler

(areas of the far west, north west, central west, northern tablelands, central to north coast, lower Hunter valley, south coast & southern tablelands)

Near neutral

(far south, Riverina, central tablelands, areas of north west, southern tablelands & central west)

Warmer

(far south east)

El Niño Southern Oscillation (ENSO)

ENSO (overall)

Neutral

Short-lived borderline-weak La Niña possible in spring, but the likelihood is decreasing

Neutral

La Niña possible in winter/spring

BoM ENSO Outlook Status

La Niña watch

La Niña watch

SOI

Neutral

Neutral (borderline positive, slowly trending to positive)

Pacific Ocean (NINO3.4)

Neutral

Neutral

(trending to cool)

Indian Ocean (IOD)

IOD negative

Warm Indian Ocean sea surface temperatures.

IOD negative

Warm Indian Ocean sea surface temperatures. Trade wind reversal.

Southern Annular Mode (SAM/AAO)

Moderately negative

(trending between weakly-strongly negative)

Weakly to moderately positive

(trending between neutral-weakly positive)

Note: Climate model outlooks are updated regularly. To check whether updates are available, use the hyperlinks provided.

Rainfall and temperature

During July, rainfall ranged from 3-420 mm across the state with most of the state receiving 25-100 mm.

The far west generally received between 10-50 mm, with areas near Broken Hill and Bourke and to the south east receiving 25-50 mm. The far north west and an area between Brewarrina and Walgett received less than 10 mm.

The majority of the central west, Riverina, far south, central and southern tablelands, Hunter valley, Sydney basin and south east received 25-100 mm, with some areas receiving over 100 mm. Most of these areas received rainfall of more than 125 per cent of average. The north west, northern tablelands and north coast generally received between 10-50 mm, with some areas receiving less. These areas received rainfall of 20-80 per cent of average. Other areas received up to 100 mm

Daytime temperatures during the month were average to above average across inland NSW, but generally above average for the coast and adjacent areas, the northern tablelands and the south east. Daytime temperatures were slightly below average across areas of the central west and the north of the far west. Well above average daytime temperatures occurred in many areas between 17-22 July. Overnight temperatures were warmer than normal, with NSW recording its fourth-warmest July on record.

Relative rainfall

Relative to historical records, rainfall during July was above average across 33 per cent of the state. Areas of the central west, Riverina, far south, southern and central tablelands, upper Hunter valley, Sydney basin, south coast and Monaro received above average rainfall for the period. Some areas of the far west also received above-average rainfall. Rainfall in these areas generally ranked in the highest 20 per cent of years. Areas of below-average rainfall occurred over the north west, far northern tablelands and along the north coast, but were limited in extent. The majority of the state (66 per cent) received near-average rainfall.

Quarterly relative rainfall was above average across 91 per cent of NSW. The lower Hunter valley and areas of the north west, northern tablelands and north coast received near-average relative rainfall for the period. Most of the state’s rainfall ranked in the highest 10-20 per cent of years.

Soil moisture

Topsoil moisture remained high during July, particularly in the central, southern and south eastern areas of the state and across some areas of the far west.

Relative to historical records, July topsoil moisture levels were well above average to extremely high across much of inland NSW and areas of the south coast. There was near-average topsoil moisture across most of the coast, the lower Hunter valley and the far south west. By the end of July, some drying had occurred, particularly in the north and west of the state.

Subsoil moisture levels improved during July across areas of central, southern, south eastern and coastal NSW. Relative to historical records, subsoil moisture was above average to extremely high across areas of far western, central, southern and south eastern NSW. It was near-average to above average across the remainder of the state.

Streamflow

Significant run off occurred during July across central and southern NSW and areas of the south east. Run off also occurred in areas of the northern tablelands and slopes, the far west and upper Hunter valley.

Yearly run off to July was above average in most of these areas, although some areas of low run off remained in other areas of the north west, northern tablelands and mid-north to north coast.

The Bureau of Meteorology's streamflow forecast indicates high streamflows are likely across most NSW monitoring stations during August to October, with some sites having a near-equal probability of high or near-median streamflows.  Near-median streamflows are likely at some northern sites, and low streamflows are likely at a small number of sites in northern and north eastern NSW.

Relative pasture growth and biomass

Relative to historical records, AussieGRASS modelled pasture growth during July was generally well above average across most of inland NSW, with the majority of coastal NSW and the Hunter valley having near-average pasture growth. Other pasture growth models indicated well above average to extremely high pasture growth across most of NSW. However, the models do not compensate well for waterlogging.

Over the quarter, AussieGRASS relative growth was above average across 69 per cent of the state and average over most of the remainder. Areas of above average growth occurred most of inland NSW, with the exception of areas of the northern Riverina, areas of the north west and the east of the central tablelands. Most of the coast and Hunter valley had average pasture growth for the period.

During July, relative biomass levels improved to average to above average levels across most of the state. Relative biomass remained low in areas of the far south west, the coast, Hunter valley and northern tablelands.


Figure 1: Relative monthly topsoil moisture

Map of relative soil moisture (upper level) average value for July 2016

Figure 2: Relative quarterly pasture growth

Map of pasture growth relative to the historical records from 1957 for May 2016 to July 2016

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 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 8-11 August 2016.

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 (8-11 August 2016). 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.