NSW Seasonal Conditions Summary October 2016

Overview

The May to September period was the wettest on record across south eastern Australia, with September also being the wettest on record for NSW.

Rainfall was above average across 87 per cent of the state during September, extending across most of inland NSW and the south coast. The remainder of the coast experienced near average conditions. Most of inland NSW received rainfall of more than 200-400 percent of normal. The far west and areas of the central west, Riverina and the north west received rainfall of more than 400 per cent of normal. Over the last six months, rainfall across most of inland NSW was in the highest 10 per cent of years.

Waterlogging and inundation restricted pasture growth in some areas, although growth continued to improve across most of the state. Growth was slow across some areas of the far west and central west. However, waterlogging and inundation was not fully taken into account by the modelling.

Relative to historical records, September pasture growth was well above average to extremely high across much of inland NSW, with near-average growth across most of the remainder.

Other pasture growth models indicated well above average to extremely high relative growth across NSW during September for temperate pasture species.

Pasture biomass levels improved across most of NSW, particularly in areas of the tablelands, south east and coast. Relative to historical records, biomass was above average to extremely high across most of the state. In many areas, hay cutting has been delayed by the wet conditions.

Stock condition is generally good to very good. Nutritional problems have eased with improvements in feed quality, but foot scald, bloat and increased worm burdens continue to be issues. Fleece rot has also been a problem in some areas.

The extremely wet conditions resulted in major crop damage from waterlogging and inundation, particularly in the central and southern areas of the state and some areas of the north west. Early indications suggest the value of crop losses is in excess of $680 million and expected to rise. Significant disease issues have occurred, particularly in pulse crops. Ascochyta and Botrytis grey mould continue to be serious problems for chickpea crops, with fungicide supplies now limited. Delays are likely for the windrowing of canola and the harvesting of winter crops. Lodging of winter cereals and canola is already occurring and may prove to be more of a problem, particularly where crops were inundated. Trafficability continues to be an issue and has resulted in ongoing problems in carrying out timely weed, insect and disease control and topdressing. On better drained areas and on lighter country, winter cereal and canola crops are showing average to above average yield potential, with particularly good yield potential for those that were early sown.

Delays have been experienced in ground preparation and weed control for the sowing of cotton, rice and other summer crops, particularly in central and southern NSW. Sowing of cotton has commenced in the north. An increased interest in aerial sowing of rice is likely to allow crops to be sown close to the ideal time. If the wet conditions continue, this will restrict the area sown to summer crops and will further delay sowing, which will have an impact on yields.

Vines and other horticultural crops are undergoing increased disease pressure. Due to the conditions, it has been difficult to undertake early season preventative fungicide applications.

Topsoil moisture remained high during September, particularly across areas of the Riverina, far south, central west and the southern and central tablelands. Relative to historical records, topsoil moisture was extremely high across all of inland NSW and average to above average across the coast.

Subsoil moisture levels continued to increase across NSW. Relative to historical records, subsoil moisture was well above average to extremely high across most of inland NSW and areas of the coast.

High levels of run off continued throughout September. Run off was well above average to extremely high across most of inland NSW, and generally average to above average across the coast. Yearly run off was well above average across most of inland NSW and the south coast.

NSW Seasonal Conditions Report – October 2016

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Seasonal outlook

The Bureau of Meteorology’s rainfall outlook for October to December (see table) indicates that wetter conditions are likely across most of NSW, with the highest probability of wetter conditions for the south. There is a near-equal probability of drier or wetter than normal conditions for the north east, including areas of the north coast and northern tablelands. Daytime and overnight temperatures are likely to be cooler than normal for the period.

During October, the rainfall and temperature outlooks are almost the same as for the seasonal outlook, with a very high probability of wetter than normal conditions for southern NSW.

The NOAA Climate Forecast System (CFS) rainfall outlook for October to December is near-neutral for most of NSW, but indicates wetter than normal conditions are likely for the south. The overall temperature outlook is for cooler than normal conditions for most of NSW.

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

A survey of the major climate models in early October indicated most (62 per cent) favour a generally near-neutral rainfall outlook (that is, a near-equal chance of drier or wetter than normal conditions) for the October to December period, with the remainder (38 per cent) favouring a generally wetter outlook. For temperature, most models (58 per cent) favoured a generally cooler than normal outlook, with about 17 per cent favouring a neutral temperature outlook and about 25 per cent favouring a warmer 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

October – December

5

8

0

3

2

7

November – January

3

5

1

2

6

1

The AussieGRASS pasture growth outlook for October to December suggests that well above average growth is possible for areas of western, southern and north western NSW as well as areas of the southern tablelands and Monaro. Generally average growth is suggested for the south east. Growth in other areas is suggested to be below average, but this is 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, with some wetter areas in the north and drier areas in the south and west. This was based on a rapidly rising SOI phase during August and September. In comparison, the Bureau of Meteorology’s rainfall outlook suggests generally wetter than normal conditions. Due to this and the assumption of nitrogen depletion, the growth outlook is likely to be underestimated in a number of areas. The growth outlook has moderate to high past accuracy for most of the state, but accuracy is low in the far west and some areas of central NSW.

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 much less likely. Sea surface temperatures are below average in the central and eastern-central equatorial Pacific and near-average to below average in the east. Sea surface temperatures in the central and eastern-central equatorial Pacific declined in early October, as a result of increased trade wind activity. La Niña-like above average sea surface temperatures are present in the western equatorial Pacific

The negative Indian Ocean Dipole (IOD) event is continuing, but weakened during late September and into early October. The event is likely to end in November or easly December, although continued warm sea surface temperatures near Sumatra mean the impacts of the event are likely to continue for some time. In a negative IOD event, above-average rainfall and cooler than normal daytime temperatures are more likely across south-eastern Australia during spring. These effects are likely to weaken into spring. Cloud remains high over areas of western Indonesia, particularly near Sumatra. The above average sea surface temperatures in this area and to the north of Australia are continuing to provide sources of moisture.

A cool subsurface temperature anomaly extends across the equatorial Pacific, reaching the surface across the central and eastern areas. It has weakened in the west, but strengthened somewhat in the central areas. The easterly Pacific trade winds were near-normal during the month, with some strengthening in the western equatorial Pacific in late September and in the central and eastern-central areas in early October. Cloud conditions near the junction of the equator and the International Date Line are low and the SOI recently increased to positive levels, both of which occur during La Niña events. Despite this, most models suggest a La Niña event is now unlikely to occur.

The Bureau of Meteorology’s ENSO outlook status remains at La Niña watch, but the CPC/IRI’s status is inactive (neutral).

The sub-tropical ridge is somewhat further north than normal and atmospheric pressure is low near Darwin, both of which favour rain-bearing systems. After being strongly positive, the southern annular mode has returned to moderately negative levels.

Climatic outlook summary

NSW Seasonal Outlook (BoM)

Current outlook

Previous outlook

Quarterly Rainfall

Wetter

(most of NSW)

Near neutral

(areas of the northern tablelands and north coast)

Near neutral – slightly wetter

(most of NSW)

Wetter

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

Quarterly Maximum Temperature

Cooler

Near neutral

(most of NSW)

Warmer

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

Quarterly Minimum Temperature

Cooler

(most of NSW)

Near neutral

(far south eastern NSW)

Warmer

(most of NSW)

Near neutral

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

El Niño Southern Oscillation (ENSO)

ENSO (overall)

Neutral

La Niña possible but unlikely

Neutral

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

BoM ENSO Outlook Status

La Niña watch

La Niña watch

SOI

Positive

Borderline positive

Pacific Ocean (NINO3.4)

Neutral

(cool)

Neutral

Indian Ocean (IOD)

IOD slightly negative – borderline neutral

IOD strongly negative

Southern Annular Mode (SAM/AAO)

Moderately negative

(trending from moderately negative to near neutral)

Strongly positive

(trending between weakly-moderately positive)

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

NSW Climate Summary

Rainfall and temperature

September was the wettest on record for NSW, with rainfall being extremely high across inland NSW. The majority of inland NSW received rainfall of more than 200 per cent of average, with the far west and areas of the central west, Riverina and north west receiving rainfall of more than 400 per cent of average. Rainfall across the state ranged from 11-320 mm.

Most of NSW received 50-200 mm for September, with much of inland NSW receiving 100-200 mm and some areas receiving 200-300 mm or more. The south to mid-north coast, much of the Monaro and the lower Hunter valley received rainfall of 50-100 mm, with some areas of the far south coast receiving 100-200 mm. The mid-north to north coast and areas of the northern tablelands generally received 25-50 mm, with an area near Kempsey receiving 10-25 mm.

Daytime temperatures were well below average during the month, being the eight-lowest on record. Daytime temperatures were near average along much of the coast, but below average across inland NSW. Overnight temperatures were well above average across the eastern half of the state, but below average in areas of the far west.

Relative rainfall

Relative to historical records, rainfall during September (PNG, 554.52 KB) was above average across 87 per cent of the state and was extremely high (ranking in the highest 10 per cent of years) across inland NSW. The south coast also received above average to well above average rainfall, with the remainder of the coast, the lower Hunter valley and the east of the northern tablelands experiencing near average conditions.

Quarterly relative rainfall (PNG, 563.41 KB) was extremely high across most of inland NSW and some areas of the north coast, being above average across 94 per cent of the state. Most of the coast had near average rainfall.

Soil moisture

Topsoil moisture remained high during September. Relative to a saturated profile, levels were high across most of the Riverina, far south, central west, north west, the southern and central tablelands and areas of the northern tablelands and far west.

Relative to historical records, September topsoil moisture levels were extremely high across most of inland NSW. Relative topsoil moisture was also above average to extremely high over areas of the north coast, Sydney basin and far south coast. The remainder of the coast generally had near-average topsoil moisture.

Subsoil moisture levels continued to increase across inland NSW during September. Relative to historical records, levels were well above average to extremely high across most of inland NSW, and generally near-average along the coast as well as areas of the north west and far south west.

Streamflow

Significant run off continued throughout September across most of inland NSW, as well as areas of the far south east, Sydney basin and areas of the far north east.

Yearly run off to September was above average to extremely high across most of inland NSW, with the exception of areas of the north west, the far south west, the east of the northern tablelands and the mid-north to north coast.

The Bureau of Meteorology's streamflow forecast indicates high streamflows are likely across most NSW monitoring stations during October to December.

Relative pasture growth and biomass

Relative to historical records, AussieGRASS modelled pasture growth during September was generally well above average to extremely high across NSW. The best growth occurred across areas of the far west, central west, north west, northern tablelands and upper Hunter valley. Growth was suppressed in some areas of the far west, central west, central tablelands, Riverina and far south, probably due to the extremely wet conditions.

Other pasture growth models indicated extremely high pasture growth across most of inland NSW, with generally above average to well above average growth across most of the southern and central tablelands, south west slopes, the lower Hunter valley and most of the coast. However, the models do not compensate well for waterlogging.

Over the quarter, AussieGRASS relative growth was above average across nearly 80 per cent of the state and average across most of the remainder. Areas of near-average growth occurred in the far west, Riverina, far south, central tablelands and along the coast.

During September, relative biomass levels continued to improve and were at well above average to extremely high levels across most of the state. The highest levels were across areas of the far west, the central west, north west, upper Hunter valley 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 10 October 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 (10 October 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.