NSW Seasonal Conditions Summary December 2016

Overview

Rainfall across NSW during November was average across 56 per cent of the state and below average across 34 per cent. Areas of the north west, northern tablelands and the coast received below average rainfall. Above average rainfall was limited to areas of the far south west.

Pasture growth during November was low across most of western NSW, as well as the western edge of the north west, central west and Riverina. Growth was low across areas of the coast, but remained moderate across most of the tablelands and slopes. Growth was also moderate across the east of the Riverina and the south east of the central west. Relative to historical records, growth was average across much of western and southern NSW but below average across most of the north of the state, the central west and the coast. Limited areas of above average growth occurred across the western, southern and central areas of the state.

Other temperate pasture growth models indicated near-average growth across most of the state but below average growth across areas of the north, the south east and the coast. Growth was above average across areas of the south, the south west slopes and the southern tablelands.

Pasture biomass levels were relatively stable across western and southern NSW, but declined slightly in other areas. The most significant declines were across the north and south coast. Relative to historical records, biomass was well above average to extremely high across most of the state, with below average biomass levels across areas of the coast. Fodder conservation continued during November with somewhat reduced quality but increased quantities.

Stock condition is generally very good, although problems due to grass seed are widespread.

Winter crop yields have generally been above average, with best yields from early sown crops. Protein levels have been lower than normal in wheat and fewer barley crops have attained malting grade. Canola oil contents have been higher than normal. Pulse crop performance has been disappointing in many areas due to the effects of waterlogging and disease, although generally above average yields have been achieved in the north. After difficulties with ground preparation for summer crops in the south, cotton establishment has been slow and rice establishment has been variable. In the north, summer crop establishment has been good with large areas sown under irrigation. Above average yields are possible for dryland sorghum if reasonable summer rainfall occurs. On the north coast, sowings of soybeans have been delayed due to dry conditions.

Topsoil moisture declined across NSW during November. Relative to historical records, topsoil moisture levels were near average across most of NSW, but were below average across most the north, north west and east. Levels remained above average in the south west.

Subsoil moisture levels were relatively stable, declining slightly in most areas. Relative to historical records, levels remained extremely high across most of inland NSW, but average in the east.

Run off was above average across areas of the far south and the central west during the month, but below average along areas of the coast and the north. Yearly run off remained above average to extremely high across most of inland NSW.

NSW Seasonal Conditions Report – December 2016

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Seasonal outlook

The Bureau of Meteorology’s rainfall outlook for December to February (see table – previous outlook) indicated drier than normal conditions are likely across most of NSW. There is a near-equal chance of drier or wetter than normal conditions across areas of the far west and the far south west. Warmer than normal daytime temperatures are likely. Warmer than normal overnight temperatures are likely across most of NSW, with a near-equal chance of cooler or warmer than normal overnight temperatures across areas of the far west and far south west NSW. There is a near-equal chance of cooler or warmer than normal overnight temperatures across areas of the far west and far south west NSW.

The most recent outlook for January to March (see table – current outlook) indicates drier than normal conditions are likely across most of NSW, with a near-equal chance of drier or wetter than normal conditions across the west and areas of the south. Temperatures are likely to be warmer than normal across most of NSW, with a near-equal chance of cooler or warmer than normal daytime and overnight temperatures in areas of the far west and areas of the south.

During December, drier than normal conditions are likely, with warmer than normal daytime and overnight temperatures across most of the state.

During January, drier than normal conditions are likely across the eastern half of NSW, with a near-equal chance of drier or wetter than normal conditions for the western half of the state. Daytime temperatures are likely to be warmer than normal across most of the state, with warmer overnight temperatures across the eastern half of NSW.

The NOAA Climate Forecast System (CFS) rainfall outlook for December to February is near-neutral for most of NSW, as is the January to March outlook. The overall temperature outlook is for warmer than normal temperatures for December to February. There is a near-neutral temperature outlook for most of NSW during January to March, with warmer temperatures likely in areas of the far west and the coast.

For December and January, the CFS rainfall outlook is near-neutral. The December temperature outlook is for warmer than normal temperatures across most of NSW, with a near-neutral outlook for areas of the central west, central tablelands, Riverina and far south. For January, the outlook is near-neutral for most of NSW.

A survey of the major climate models in early December showed variability in the rainfall outlooks for the December to February period. Most favoured a generally near-neutral outlook (that is, a near-equal chance of drier or wetter than normal conditions).  Two models favoured a generally wetter outlook and four a generally drier outlook. The Bureau’s seasonal outlook for the period was included in the latter. For temperature, most models favoured a warmer than normal outlook, with four favouring a generally near-neutral outlook. One model 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

December – February

2

9

4

9

4

1

January – March

1

6

3

9

1

0

The AussieGRASS pasture growth outlook for December to February suggests that below average pasture growth is likely in most areas of NSW. However, this is likely to be due to the model assuming limited soil nitrogen. Near-average growth is suggested for the Riverina, far south, Monaro, south coast and some areas of the far west.

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 between December and February, with some wetter areas across the far north east, and some drier areas across central, far western and coastal NSW. This was based on a rapidly rising SOI phase during October and November. In comparison, the Bureau of Meteorology’s December to February rainfall outlook suggests drier than normal conditions across most of NSW. The growth outlook has moderate to high past accuracy for the coast and tablelands, but accuracy is low across most of NSW.

El Niño Southern Oscillation (ENSO)

The Pacific Ocean remains in an ENSO-neutral state. Most models suggest neutral conditions continuing into summer, although with slightly cooler than average sea surface temperatures in the central equatorial Pacific. A La Niña event is now unlikely.

Sea surface temperatures over the last month were below average in the central, eastern-central and eastern equatorial Pacific. La Niña-like above average sea surface temperatures are present in areas of the western equatorial Pacific to the north of Australia.

The negative Indian Ocean Dipole (IOD) event has ended. Continued warm sea surface temperatures near Sumatra and to the north of Australia may provide potential moisture for NSW if the right conditions occur.

During November cloud remained high over areas of Australia, Papua New Guinea and Indonesia, particularly near Sumatra. Cloud remained low near the junction of the equator and the International Date Line.

A cool subsurface temperature anomaly extends across the central and eastern equatorial Pacific from depth to the surface. Weak to moderate warm anomalies are present in the west.

The easterly Pacific trade winds were near average over the month, except for a small area in the western Pacific. The SOI remained neutral.

The Bureau of Meteorology’s ENSO outlook status has shifted from La Niña watch to inactive. The CPC/IRI’s status remains at La Niña advisory, suggesting that La Niña conditions are present but with a neutral outlook for summer to early autumn. Note that the Bureau and CPC/IRI use different thresholds for such events.

The sub-tropical ridge is in a near normal position near the Great Australian Bight, with a shift towards the north in the Tasman Sea. Pressure in the southern ocean is very low, with particularly high pressure over Antarctica, leading to a negative Southern Annular Mode (SAM).

The SAM was strongly negative in early-mid November, which contributed to the drier conditions. It is currently weakly to moderately negative and likely to stay at these levels into late December and early January. The drier monthly and seasonal outlooks are due to the likelihood of the SAM remaining negative.

A negative SAM during summer means that westerly winds and high pressure systems are generally further north than normal. This can result in drier than normal conditions, as it acts to prevent moisture being drawn from the north.

Climatic outlook summary

NSW Seasonal Outlook (BoM)

Current outlook

Previous outlook

Quarterly Rainfall

Drier

(most of NSW)

Near neutral

(areas of western and south western NSW)

Drier

(most of NSW)

Near neutral

(areas of far western and far south western NSW)

Quarterly Maximum Temperature

Warmer

(most of NSW)

Near neutral

(areas of far western NSW)

Warmer

Quarterly Minimum Temperature

Warmer

(most of NSW)

Near neutral

(areas of western and south western NSW)

Warmer

(most of NSW)

Near neutral

(areas of far western and far south western NSW)

El Niño Southern Oscillation (ENSO)

ENSO (overall)

Neutral

La Niña unlikely

Neutral

La Niña possible but unlikely

BoM ENSO Outlook Status

Neutral

La Niña watch

SOI

Neutral

Neutral

Pacific Ocean (NINO3.4)

Neutral

(slightly cool)

Neutral

(cool)

Indian Ocean (IOD)

Neutral

(slightly warm)

Negative IOD is weakening – trending to neutral

Southern Annular Mode (SAM/AAO)

Weakly to moderately negative

Moderately to strongly negative

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

Rainfall and temperature

Rainfall was near average across southern and central NSW during November, but below average across the north west, northern central west, northern tablelands, much of the coast and areas of the Monaro. Rainfall in these areas was less than 20 to 60 per cent of average.

Rainfall across the state ranged from 1-159 mm. The far west generally received between 1-25 mm, with recordings of up to 50 mm in the south and east. The eastern, central and southern areas of the state generally received 25-50 mm, with the north west and northern central west generally receiving 5-25 mm. Areas of the tablelands, Hunter valley, mid north coast, far north coast and the south west slopes received up to 100 mm, as did the alpine areas.

Daytime temperatures were above average across most of eastern, northern and central NSW, particularly along the Illawarra to north coast and Hunter valley. Daytime temperatures were near average across most of the south. Overnight temperatures were below average across most of NSW but near average across the south east to mid-north coast, Monaro, areas of the south west slopes and the southern and central tablelands.

Relative rainfall

Relative to historical records, rainfall during November was average across 56 per cent of the state and below average across 34 per cent.

Below average relative rainfall occurred across the north, north west and north coast, as well as areas of the Sydney basin, south coast and Monaro. Above average relative rainfall was restricted to areas of the far south west and the far south.

Quarterly relative rainfall was dominated by the very wet September conditions. It was above average across 81 per cent of the state, being extremely high across much of far western, southern and central NSW. Areas of below average rainfall occurred across the south coast, Sydney basin and north coast.

Soil moisture

Topsoil moisture declined during November to levels of less than 20 per cent of a saturated profile across the west, and less than 30 per cent across most of the remainder of NSW. Levels were slightly higher across areas of the tablelands and upper Hunter valley.

Relative to historical records, November topsoil moisture levels were below average across a quarter of NSW, including most of northern, north western and eastern NSW. Levels were above average in the south west, and near average across the majority of NSW.

Subsoil moisture levels remained relatively stable, declining slightly in most areas. Particular declines occurred along the coast, tablelands and in the south. Relative to historical records, levels remained extremely high across most of inland NSW, but average across the coast and the east of the tablelands.

Streamflow

Run off remained above average across some areas of the far south and the central west during the month, but was below average along areas of the coast and the north.

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

The Bureau of Meteorology's streamflow forecast indicates near-median streamflows are likely across most NSW monitoring stations during December to February. High flows are likely at some southern locations.

Relative pasture growth and biomass

Relative to historical records, AussieGRASS modelled pasture growth during November was average across most of western and southern NSW. Relative growth was below average across most of the coast, Hunter valley, north west, northern tablelands and the central west. Limited areas of above average growth occurred across the western, southern and central areas of the state.

Other pasture growth models indicated near-average growth across most of the state but below average growth across areas of the north, areas of the Monaro and across most of the coast. Growth was above average across areas of the south, the south west slopes and the southern tablelands.

Over the quarter, AussieGRASS relative growth was above average across 47 per cent of the state and average across most of the remainder. Most of the far west, north west, central west and south had above average growth. Areas of below average growth occurred in near Cobar and over areas of the north coast, the Sydney basin and the south coast.

During November, relative biomass levels remained well above average to extremely high across most of the state. Relative biomass was greatest across areas of the far west, the central west, north west, northern tablelands and areas of the Riverina and far south. Areas of the south coast and Sydney basin had below average relative biomass.

Figure 1: Relative monthly topsoil moisture

soil moisture map nov 2016 large

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 15 December 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 (15 December 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.