NSW Seasonal Conditions Summary January 2017

Overview

Rainfall across NSW during December was near average across 57 per cent of the state and above average across 33 per cent. Areas of the north coast, northern tablelands, Hunter valley and the far south west received below average rainfall. Above average rainfall occurred across areas of the far west, the central west and the Riverina.

Pasture growth slowed during December across most of western NSW, the north west, the western edge of the Riverina, areas of the upper Hunter and the north of the central west. Growth was also slow across areas of the coast, but remained moderate across most of the Monaro, tablelands and slopes. Growth was moderate across the eastern and central Riverina, the far north west and the south of the central west. Relative to historical records, growth was average across much of NSW but below average across the north east of the state, as well as areas of the central west, central tablelands and upper Hunter valley. Above average growth occurred across areas of the far west and the central Riverina.

Other pasture growth models indicated near-average growth across the southern and central areas of the state. Below average growth occurred across most of the north, the north coast and areas of the northern tablelands, Hunter valley and south coast. Growth was above average across the central and eastern Riverina and areas of the far west.

Pasture biomass declined across most of NSW, particularly across areas of the coast, tablelands and north west. Relative to historical records, biomass was well above average to extremely high across much of inland NSW, but average across the tablelands, slopes, Monaro and the Hunter valley. Relative biomass was below average across much of the coast.

Stock condition remained generally good. Grass seeds continued to be a problem in many areas.

Warmer temperatures during mid-late December accelerated summer crop growth and increased crop water requirements, after a slow start in some areas. In the south, above average rainfall has benefitted the growth of summer crops and lucerne. Crop development has been slightly delayed by late sowing and cooler conditions in early December. The yield potential for rice is average to above average. For dryland sorghum in the north west the yield outlook remains good. There is a high chance of above average yields providing average to above average rainfall is received during the remainder of the growing season. The yield potential of irrigated crops is high, despite the current hot, dry conditions. The cotton production forecast is for 4.4 million bales, but may be revised down if the current conditions continue.

Topsoil moisture declined across areas of western NSW and the tablelands. Relative to historical records, topsoil moisture levels were near average across most of NSW. Levels were above average in the far west and areas of the central west and Riverina, but below average across areas of the north west and the coast.

Subsoil moisture levels declined slightly in most areas. Relative to historical records, levels remained extremely high across most of inland NSW. This is of benefit for summer crop growth. Subsoil moisture was average across the coast and the east of the tablelands, but below average along areas of the coast.

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

Subscribe to the Seasonal Conditions e-newsletter

The Seasonal Conditions e-newsletter will let you know as soon as the monthly report is published. Subscribe now.

Seasonal outlook

The Bureau of Meteorology’s rainfall outlook for January to March (see table) 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 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.

Due to some weakening of the negative Southern Annular Mode (see below) some climate model outlooks for January and January to March rainfall have shifted more towards near-neutral.

The NOAA Climate Forecast System (CFS) rainfall outlook for January to March is near-neutral for most of NSW. There is an area where below-average rainfall is possible across part of the south, and adjacent to the north coast. The overall temperature outlook is for warmer than normal conditions across most of NSW, except for some areas of the southern tablelands and north east.

For January, the CFS rainfall  and temperature outlook is near-neutral for most of NSW.

A survey of the major climate models in early January showed some variability in the rainfall outlooks for the January to March period. Most (71 per cent) 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 two a generally drier outlook. The Bureau’s seasonal outlook for the period was included in the latter. For temperature, most models (69 per cent) favoured a warmer than normal outlook, with four favouring a generally near-neutral outlook. Model accuracy tends to be lower into early autumn.

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

January – March

2

10

2

9

4

0

February – April

1

5

3

7

2

0

The AussieGRASS pasture growth outlook for January to March suggests that below average pasture growth is possible across areas of the far west, north west, tablelands, upper Hunter valley, Sydney basin and north coast. However, this is likely to be due to the model assuming limited soil nitrogen in many of these areas. Above average growth is suggested for areas of the far north west, Riverina, far south, Monaro, coast, central west and central and southern tablelands.

The seasonal rainfall prediction that the growth outlook is based upon is for near-equal chance of drier or wetter than normal conditions for most of NSW between January and March, with some drier areas across the far south east and far west of NSW. This was based on a near zero SOI phase during November and December. In comparison, the Bureau of Meteorology’s January to March rainfall outlook suggests drier than normal conditions across most of NSW, with a near-equal chance of above or below median rainfall for the west.

The current growth outlook has a low past accuracy across most of NSW, and accuracy is likely to remain low into autumn.

El Niño Southern Oscillation (ENSO)

The Pacific Ocean remains in an ENSO-neutral state. Most models suggest neutral conditions continuing throughout summer and into early autumn.

Sea surface temperatures during December were below average in the central, eastern-central and eastern equatorial Pacific, but the cool anomalies have weakened and warming is expected to continue. Above average sea surface temperatures remain present in areas of the western equatorial Pacific to the north of Australia and in the Indian Ocean near Sumatra. These warm anomalies have been weakening due to the effects of the monsoon.

During December cloud remained high over areas of Australia, Indonesia and the Philippines. Cloud remained low near the junction of the equator and the International Date Line and to its east and west.

The cool subsurface temperature anomaly extending across the central and eastern equatorial Pacific has weakened. Warm anomalies are present in the west, but have recently weakened.

The easterly Pacific trade winds were near average over the month. The SOI remained neutral.

The Bureau of Meteorology’s ENSO outlook status is 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. Pressure across most of the southern ocean remains very low, with particularly high pressure over Antarctica, leading to a continued negative Southern Annular Mode (SAM).

The SAM was weakly to moderately negative during December, with the outlook suggesting it will continue at these levels with a possible return to near-neutral levels in late January. The drier monthly and seasonal outlooks are partly due to the likelihood of the SAM remaining negative, although as the negative SAM has weakened somewhat the outlooks for January rainfall have shifted more towards near-neutral.

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 reduce the likelihood of 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

Neutral

La Niña possible but unlikely

BoM ENSO Outlook Status

Neutral

La Niña watch

SOI

Neutral

Neutral

Pacific Ocean (NINO3.4)

Neutral

(slightly cool but warming)

Neutral

(cool)

Indian Ocean (IOD)

Neutral

(slightly warm but cooling)

Negative IOD is weakening – trending to neutral

Southern Annular Mode (SAM/AAO)

Weakly to moderately negative (trending to weakly negative-neutral)

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 across NSW was near average across much of NSW during December and above average across areas of the far west, Riverina and central west. Below average rainfall occurred across areas of the north coast, northern tablelands, Hunter valley, the far south east, far south and far south west. Rainfall in these areas was less than 20 to 60 per cent of average.

Rainfall across the state ranged from 5-203 mm, with most of NSW receiving between 25-100 mm for the month. The higher falls occurred across most of the tablelands, coast and the eastern areas of the north west, central west and Riverina. Rainfall in areas of the south, south west and far north west was less than 25 mm. The far west generally received between 25-50 mm, with recordings of up to 100 mm in in some areas. Areas near Bourke and in the south received less than 25 mm.

It was the second-warmest December on record across NSW. Daytime temperatures were well above average across all but areas of far western NSW. Overnight temperatures were well above average across most of the state, but near average in the far north east.

Relative rainfall

Relative to historical records, rainfall during December was near average across 57 per cent of the state and above average across 33 per cent.

Below average relative rainfall occurred across the north coast and areas of the northern tablelands, the Hunter valley, the far south west and the far south east. Above average relative rainfall occurred across areas of the far west and eastern and central areas of the central west and the Riverina. The remainder of the state had near-average relative rainfall.

Quarterly relative rainfall was average across 58 per cent of the state, above average across 20 per cent and below average across 22 per cent. Above average rainfall occurred across areas of the far west, plus limited areas of the central west, Riverina and southern tablelands. Below average rainfall occurred across most of the coast, particularly the north coast. Areas of below average rainfall also occurred across areas of the north west and the east of the northern tablelands.

Soil moisture

Topsoil moisture declined across areas of western NSW and the tablelands during December. It remained at levels of less than 20 per cent of a saturated profile across much of NSW, and less than 30 per cent across most of the east.

Relative to historical records, December topsoil moisture levels were near average across most of NSW. Levels were above average in the far west and areas of the central west and Riverina, but below average across areas of the north west and the coast (particularly the north coast).

Subsoil moisture levels declined slightly in most areas. Relative to historical records, levels remained extremely high across most of inland NSW, but average across the coast and the east of the tablelands. Below average subsoil moisture occurred along areas of the coast, extending from the Illawarra to north coast.

Streamflow

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

Yearly run off to December remained above average to extremely high across much of 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 near-median streamflows are likely across most NSW monitoring stations during January to March. Low streamflows are possible at some northern locations.

Relative pasture growth and biomass

Relative to historical records, AussieGRASS modelled pasture growth during December was average across one third of NSW. Most of central, southern and south eastern NSW had near average relative growth, together with areas of the far west. Below average growth occurred across much of the north coast, upper Hunter valley and the northern tablelands. Areas of below average growth also occurred across the central and southern tablelands, the north west and the central west. Above average growth occurred across areas of the far west and the central Riverina.

Other pasture growth models indicated near-average growth across southern and central NSW but below average growth across most of the north, the north coast and areas of the northern tablelands, Hunter valley and south coast. Growth was above average across the central and eastern Riverina and areas of the far west.

Over the quarter, AussieGRASS relative growth was near average across 39 per cent of NSW. Areas of the far west, north west, central west, Riverina and south had above average growth. Areas of below average growth occurred in near Cobar and across areas of the north coast, Hunter valley, northern tablelands, the Sydney basin, the south coast and the west of the central west.

During December, relative biomass levels remained well above average to extremely high across much of inland NSW. Relative biomass was near-average across most of the tablelands, slopes, Monaro and the Hunter valley. Areas of the north coast, south coast and the Sydney basin had below average relative biomass, as did some areas of the northern tablelands and Hunter valley

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 15 January 2017.

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 January 2017). 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.