NSW Seasonal Conditions Summary September 2016

Highlights

Overview

August was wetter than normal across 77 per cent of NSW. Most of western, northern and north eastern NSW as well as areas of central and southern NSW experienced wetter than normal conditions. In particular, the north east received rainfall in excess of 200 per cent of normal. The far south east experienced drier than normal conditions.

The wet conditions restricted pasture growth in some areas, although it was maintained across most of the state. Growth improved across areas of the central to north coast, Hunter valley and most of the tablelands. Growth was restricted across some areas of the tablelands and the far south east, as well as areas of the far west. However, it is likely that waterlogging in central and southern NSW was not fully taken into account by the modelling.

Relative to historical records, August pasture growth was well above average across most of northern, north eastern, western and central NSW and near-average across the remainder of the state.

Other pasture growth models indicated well above average to extremely high relative pasture growth during August across western, central, north western and southern NSW and the central to north coast. However, growth was below average for much of the tablelands and the south east.

Pasture biomass levels remained low across areas of the tablelands, south east and far north west, but continued to improve across most of the remainder of NSW. Relative to historical records, biomass was generally average to above average.

Stock condition remains reasonably good, with supplementary feeding declining as pasture growth improved. Nutritional problems have eased, but foot scald, bloat and increased worm burdens continue to be issues.

Wet weather during August and early September continued to take a toll on winter crops, with late sown crops suffering significant damage from waterlogging and inundation. The damage has been greatest on heavy or sodic soils and in low lying areas. Losses from 10-30 per cent of sown area to complete crop failure have occurred in some areas of the central west and Riverina. Pulse crops have been worst affected. The wet conditions have greatly increased disease problems such as yellow leaf spot and stripe rust in wheat and net blotch and bacterial stripe in barley. Pulse crop diseases such as Ascochyta blight and Botrytis grey mould in chickpeas are significant threats to production. Weeds have been more of an issue than in most years, due to limited control opportunities. Trafficability remains a problem although the warm, fine weather in late August allowed a short opportunity to undertake weed, pest and disease control and topdressing on better drained areas. In many cases, aerial application has been the only alternative. Rainfall in early-mid September has been of benefit to crops in areas of the north west, particularly between Moree and Inverell and the border.

Due to the conditions and associated denitrification, winter crop development in many areas has been slower than normal and cereals have shown reduced tillering. However, in the better drained areas and on lighter country, winter cereal and canola crops have average to above average yield potential. Early sown crops are showing the best potential. Lodging may prove to be an issue due to restricted root development. Some frost damage has occurred, but has generally been limited to areas of the south west slopes.

In some localities where sowing of winter crops could not be completed or severe crop damage has occurred, growers are considering sowing summer forage and grain crops, lucerne and cotton.

Topsoil moisture remained high during August, particularly across areas of central, southern and north eastern NSW and some areas of the far west. Relative to historical records, it was well above average to extremely high across much of western, central and north eastern NSW. Relative topsoil moisture was near-average over most of the remainder of NSW, but low in the far south east.

Subsoil moisture levels improved during August across areas of central, southern and coastal NSW. Relative to historical records, it was above average to extremely high across areas of far western, central, southern and south eastern NSW.

Significant run off continued throughout August. Above average run off occurred across areas of northern, central and southern NSW, areas of the far west and the mid-north to north coast. Run off was average to below average across south eastern NSW.

NSW Seasonal Conditions Report – September 2016

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Seasonal outlook

The Bureau of Meteorology’s rainfall outlook for September to November (see table) indicates that there is a near-equal chance of drier or wetter than normal conditions across NSW, with a slightly increased possibility of wetter conditions. Wetter than normal conditions are possible in areas of the central west and Riverina. There is a near-equal chance of cooler or warmer than normal daytime temperatures across most of NSW, with warmer than normal conditions likely across the far west, areas of the western Riverina, the far south east and the Illawarra to mid-north coast. Overnight temperatures are likely to be warmer than normal across most of NSW, with a near-equal chance of cooler or warmer than normal conditions across areas of the north west, northern tablelands and north coast.

During September, there is a near-equal chance of drier or wetter than normal conditions across most of NSW. Wetter than normal conditions are likely across the southern areas of the central west, the western areas of the Riverina, areas of the far south and the southern half of the far west. There is a near-equal chance of cooler or warmer than normal daytime and overnight temperatures across most of NSW. Warmer than normal temperatures are likely across areas of the far west. Cooler than normal daytime temperatures are likely across some areas of the central tablelands, central west and north west. Warmer than normal overnight temperatures are likely across the far south east, with cooler than normal conditions in areas of the far south.

The NOAA Climate Forecast System (CFS) rainfall outlook for September to November is near-neutral for most of the northern half of NSW, but indicates wetter than normal conditions are likely the southern half of NSW. The overall temperature outlook is near-neutral for most of NSW, with cooler than normal conditions likely for areas of southern and central NSW.

For September, the CFS rainfall outlook is near-neutral for most of NSW, but indicates wetter than normal conditions are likely for areas of south-western NSW. The temperature outlook is near-neutral.

A survey of the major climate models in early September indicated just over 70 per cent favour a wetter than normal rainfall outlook for September to November, with the remainder favouring a neutral outlook (that is, a near-equal chance of drier or wetter than normal conditions). For the period, about 40 per cent of models favoured a warmer than normal outlook, about 40 per cent a neutral temperature outlook and about 20 per cent favoured a cooler than normal outlook.

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

September – November

10

4

0

5

5

3

October – December

4

4

1

3

4

2

The AussieGRASS pasture growth outlook for September to November suggests that well above average growth is likely for most of the west and areas of southern and north western NSW. Above average growth is likely for areas of the central west, tablelands, Monaro and areas of the north coast. Generally below average growth is suggested for the eastern edge of the far west, the western edge of the central west and the Sydney basin. The areas of below average growth are most likely based on the model assuming soil nitrogen may be limited, as a result of leaching, denitification and depletion.

The seasonal rainfall prediction that the growth outlook is based upon is for a near equal chance of above or below median rainfall for most of NSW. This was based on a near-zero SOI phase during July and August. The Bureau of Meteorology’s rainfall outlook is similar. The pasture growth outlook has moderate to high accuracy for most of the state.

El Niño Southern Oscillation (ENSO)

The Pacific Ocean remains in an ENSO-neutral state. Most models suggest a neutral outlook for spring, with a La Niña event now being unlikely. Sea surface temperatures are near-average to slightly below average in the eastern and central equatorial Pacific while there are La Niña-like above average temperatures in the west.

A negative Indian Ocean Dipole (IOD) event is occurring and strengthened again recently, but is expected to weaken into spring. This means above-average rainfall and cooler than normal daytime temperatures are more likely across south-eastern Australia during spring. These effects are likely to weaken as spring progresses. Indian Ocean trade winds have intensified.

A cool subsurface temperature anomaly extends across the equatorial Pacific, reaching the surface across the central and eastern areas. It has weakened, making a La Niña event less likely. The Pacific trade winds were near-normal during the month. Cloud conditions near the International Date Line decreased and the SOI recently increased to borderline positive levels, which occur during La Niña events.

A short-lived borderline La Niña event remains possible in spring, although it is now unlikely. The Bureau of Meteorology’s ENSO outlook status remains at La Niña watch, but the CPC/IRI’s status moved to inactive (neutral) this month.

Warm sea surface temperatures exist in areas to the north, south east, north east and north west of the continent. Cloud remains high over areas of western Indonesia, particularly near Sumatra. These areas remain potential sources of moisture for spring rainfall. The sub-tropical ridge is somewhat further north than normal, allowing the passage of fronts. The southern annular mode is currently strongly positive and trending towards moderately positive. The latter is less conducive to rainfall across much of inland NSW but can result in more rainfall over eastern and areas of central NSW.

Climatic outlook summary

NSW Seasonal Outlook (BoM)

Current outlook

Previous outlook

Quarterly Rainfall

Near neutral – slightly wetter

(most of NSW)

Wetter

(areas of the northern Riverina and the south of the central west)

Wetter

Quarterly Maximum Temperature

Near neutral

(most of NSW)

Warmer

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

Cooler

(most of NSW)

Near neutral

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

Quarterly Minimum Temperature

Warmer

(most of NSW)

Near neutral

(areas of the north west, northern tablelands and north coast)

Near neutral

(most of NSW)

Warmer

(areas of the far west and far south east)

Cooler

(areas of the north west and central west)

El Niño Southern Oscillation (ENSO)

ENSO (overall)

Neutral

Short-lived borderline 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

Borderline positive

Neutral (borderline positive, slowly trending to positive)

Pacific Ocean (NINO3.4)

Neutral

Neutral

(trending to cool)

Indian Ocean (IOD)

IOD strongly negative

IOD negative

Warm Indian Ocean sea surface temperatures.

Southern Annular Mode (SAM/AAO)

Strongly positive

(trending between weakly-moderately positive)

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.

NSW Climate Summary

Rainfall and temperature

August was the wettest since 2003, with rainfall ranging from 3-332 mm across the state. An East Coast Low early in the month produced strong winds and heavy rainfall across north-eastern NSW.

Most of NSW received 25-100 mm for August. Areas of the central west, central and southern tablelands, Riverina, far south and north west received 50-100 mm for the period, with other areas generally receiving 25-50 mm.

The west generally received between 10-50 mm, with areas near Ivanhoe and Cobar receiving 50-100 mm. Areas of the far north west and an area near Bourke received less than 25 mm. The Monaro and far south east of the state also received less than 25 mm for August.

Most of the coast received 25-100 mm. The north east of the state received the most rainfall, with areas of the northern tablelands, north coast and areas of the Hunter valley receiving 100-200 mm or more.

Daytime and overnight temperatures were slightly above average during the month. Daytime temperatures were slightly above average across the east of the state, particularly in the far south east and far south west, but slightly below average for most of western NSW. Overnight temperatures were similar, but above average for areas of the mid-north to north coast, far north west and Hunter valley.

Relative rainfall

Relative to historical records, rainfall during August was above average across 77 per cent of the state and generally ranked in the highest 20 per cent of years.  Areas of the central west, central and southern tablelands and south west slopes had near-average rainfall. Areas of below-average rainfall occurred across the Monaro, far south east and some of the alpine areas.

Quarterly relative rainfall was above average across 95 per cent of NSW. Isolated areas of the Hunter valley, far north west and far south west received near-average 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 August, particularly across areas of the central west, central tablelands, the eastern edge of the north west, northern tablelands, north coast and some areas of the far west.

Relative to historical records, August topsoil moisture levels were well above average to extremely high across much of western, central and northern NSW. Relative topsoil moisture was generally near-average across most of the remainder of NSW, but low in the far south east.

Subsoil moisture levels improved during August across areas of central, southern and coastal NSW. Relative to historical records, it was above average to extremely high across areas of far western, central, southern and south eastern NSW. Above average subsoil moisture also occurred across areas of the north west, upper Hunter valley and the northern tablelands. Subsoil moisture was near-average across the remainder of the state, including most of coastal NSW.

Streamflow

Significant run off continued throughout August, particularly across areas of the far west, far south, Riverina, central west, mid-north to north coast, north west and northern tablelands. Run off was average to below average for south eastern NSW.

Yearly run off to August was above average across southern and central NSW, the tablelands and areas of the north west, northern tablelands and far west. Run off was near-average across most of the remainder of NSW, but below average over areas of the north west, Liverpool Plains and scattered areas of the north coast.

The Bureau of Meteorology's streamflow forecast indicates high streamflows are likely across most NSW monitoring stations during September to November, with most of the remaining sites likely to have near-median streamflows.

Relative pasture growth and biomass

Relative to historical records, AussieGRASS modelled pasture growth during August was generally average to above average across NSW. The best growth occurred across areas of the north west, far west, central west and the coast.

Other pasture growth models indicated well above average to extremely high pasture growth across most of NSW, with the exception of the tablelands, south west slopes, the south east and areas of the Hunter valley. Growth was well below average in these areas due to cloudy, wet conditions. However, the models do not compensate well for waterlogging.

Over the quarter, AussieGRASS relative growth was above average across 76 per cent of the state and average across most of the remainder. Most of inland NSW had above average growth, as well as areas of the north coast and the Sydney basin.

During August, relative biomass levels continued to improve and were at average to above average levels across most of the state. Central NSW had the highest levels. It remained low in areas of the far south west, the south coast and scattered areas of the central and northern tablelands.

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 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 13 September 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 (13 September 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.