NSW Seasonal Conditions Summary May 2016

Highlights

  • Rainfall across inland NSW was limited until late April. Most of NSW received rainfall of 20-60 per cent of normal.
  • The rainfall outlook for May to July indicates wetter conditions are likely across NSW. Warmer daytime temperatures are likely across eastern, southern and south eastern NSW and warmer overnight temperatures across the state.
  • During May, there is a near equal chance of drier or wetter than normal conditions across most of NSW, with wetter conditions likely in the far south west. Warmer than normal temperatures are likely.
  • The El Niño event is close to ending. Half the global climate models suggest a La Niña event is likely in winter and spring, with many also indicating a negative IOD is likely. The Bureau of Meteorology’s ENSO outlook status is at La Niña watch.
  • Topsoil moisture levels remained low, but improved in late April in areas of western, central and north eastern NSW. Levels have improved further from the early May rainfall.
  • Pasture growth and biomass levels were low during April. The late April/early May rainfall will encourage growth, but warmer than normal conditions will be necessary for winter production. Supplementary feeding has been necessary to maintain stock condition in many areas.
  • Dual purpose winter crops were dry sown or sown on marginal moisture. Faba bean and lupin sowings are mostly complete and about 90 per cent of canola has been sown. The late rainfall stimulated further sowings and crop establishment. Weed control will be a priority during winter.
  • Harvesting of maize is complete, and cotton is continuing with above average yields obtained from irrigated crops.
  • Stock water supplies remain limited in many areas, though late April/early May rainfall will ease the situation.

Overview

Rainfall across inland NSW during April was limited until late in the month. Falls were below average across 25 per cent of the state, particularly across northern, eastern and southern NSW. Most of the state received rainfall of about 20-60 per cent of normal.

A lack of effective rainfall up to the end of April, following warm, dry weather in February and March resulted in low levels of pasture production across most of inland NSW. Particular declines in growth occurred across areas of the Riverina, far south, far west, south east and the central and southern tablelands. Growth across the rest of NSW generally remained low. The late April and early May rainfall stimulated growth of annual and perennial pastures, but warmer than normal conditions will be necessary to ensure reasonable winter production. Winter production is likely to be limited in tablelands areas.

Relative to historical records, April pasture growth was below average across areas of the far north west, north west, central west, northern tablelands, Hunter valley, Sydney basin, and south and north coast. It was near average across most of the remainder of NSW.

Pasture biomass levels declined across most of NSW during April, particularly across areas of the slopes, tablelands and coast. Modelling indicates that biomass levels had declined to less than 500 kg/ha over much of NSW during April.

Stock condition remains moderate to good; although in inland areas supplementary feeding has been necessary to slow declines in stock condition. To reduce pressure on pastures, landholders in some areas reduced stock numbers.

Sowings of dual purpose and long season winter crops continued, although to the end of April most had been dry sown or sown on marginal moisture. Up to late April, less than a third of the total winter crop area had been sown, and establishment had been patchy. About 90 per cent of canola crops and the majority of faba beans and lupins had been sown by early May. Chickpea sowings are likely to commence in mid-May in the north. The late April-early May rainfall stimulated further winter crop sowing, promoted establishment of dry sown crops and reduced moisture stress on establishing crops. Weed control will be a priority due to the lack of control opportunities prior to sowing.

Harvesting of maize is complete, with yields generally above average. Cotton harvesting is continuing, with well above average yields for irrigated crops.

Modelled topsoil moisture remained at low levels across most of NSW during April, but improved at the end of the month in some areas of far western, central, southern and north eastern NSW. Further improvements resulted from the early May rainfall.

Subsoil moisture levels declined slightly during April, with the eastern areas of NSW showing the greatest decline.

Stock water supplies remain low in many areas, although the late April and early May rainfall will ease the situation. Areas of some concern are in the central, southern and northern tablelands, the south west and northern slopes, the north west, the west and north east of the central west, the upper Hunter valley and areas of the far south and far west. Run off from the late April and early May rainfall increased slightly, but by early May was still limited.

NSW Seasonal Conditions Report – May 2016

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Seasonal outlook

The Bureau of Meteorology’s rainfall outlook for May to July indicates wetter than normal conditions are likely across NSW. Warmer than normal daytime temperatures are likely across most of eastern and southern NSW, as well as the central tablelands, most of the northern tablelands, areas of the northern slopes and Liverpool Plains and the eastern areas of the central west. There a near-neutral outlook for daytime temperatures across areas of the far west, far south west and the western areas of both the north west and the central west. This means there is a near-equal chance of cooler or warmer than normal conditions in these areas. Overnight temperatures are likely to be warmer than normal across NSW.

During May, there is a near-neutral rainfall outlook for most of NSW. Wetter than normal conditions are likely in an area of the far south west. Warmer than normal daytime and overnight temperatures are likely.

The NOAA Climate Forecast System (CFS) rainfall outlook for May to July indicates wetter than normal conditions are likely for most of the state, particularly in western, southern and central NSW. There is a near-neutral outlook for areas of the mid-north to north coast. Warmer than normal conditions are indicated for NSW, especially across the north, north east and along the coast.

For May, the NOAA CFS rainfall outlook is near-neutral across northern and eastern NSW. Wetter than normal conditions are shown as likely for western and southern NSW. Warmer than normal temperatures are likely, particularly in the north, north east and along the coast. For June, the outlook indicates wetter than normal conditions over most of NSW and a near-neutral outlook for the coast. Warmer than normal conditions are shown as likely over most of NSW, particularly in the north east. There is a near-neutral temperature outlook for the far south west.

A survey of the major climate models in late April indicated most favour a wetter than normal or a near-neutral rainfall outlook for May-July, with one model suggesting slightly drier conditions for the south, far west and far north west. All the models surveyed indicate 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

May - July

8

6

0

12

0

0

June - August

8

3

0

9

1

1

The AussieGRASS pasture growth outlook for May to July suggests below average growth is likely for much of the west. Average growth is suggested for much of the north west, with some areas of above average growth in the central west, south west slopes and southern tablelands. Below average growth is suggested for the north of the central west, the east and north of the central tablelands and much of the northern tablelands, upper Hunter valley, south east, far south and Riverina. The outlook for the central to north coast suggests average to somewhat above average growth.

However, the seasonal rainfall prediction that the growth outlook is based upon is near-neutral for most of eastern and central NSW, but below average for much of the south, far west and far north west. This was based on a rapidly falling SOI during March and April. The rainfall outlook is very different to that of the Bureau of Meteorology. The pasture growth outlook also has poor accuracy for most of the state. Due to this and the inconsistency with the Bureau of Meteorology’s rainfall outlook, the growth outlook should be regarded with caution.

El Niño Southern Oscillation (ENSO)

The Pacific Ocean remained in a weak El Niño event during April and early May, but is now in a borderline El Niño-neutral state.

Sea surface temperatures in the NINO 3 and 3.4 regions continued their decline into early May. The NINO 3 area has now returned to neutral and the NINO 3.4 area is slightly below the El Niño threshold (as at early May). Temperatures in the eastern areas have also declined to neutral levels. The cool subsurface temperature anomaly continued to expand with warm temperatures in the central Pacific now restricted to the surface only. The cool anomaly has expanded to reach the surface in the east. The atmospheric indicators have had a slower progression towards neutral, but the SOI and central Pacific cloud conditions are now also trending towards normal levels, with trade winds near normal since early March.

The current temperatures and modelling suggest that the El Niño event is likely to end very soon. Half the dynamical global climate models suggest NINO 3.4 sea surface temperatures will be near or below La Niña thresholds during winter-spring. The Bureau of Meteorology’s ENSO outlook status is at La Niña watch, as is that of the CPC/IRI. Many models also indicate a negative Indian Ocean Dipole (IOD) event is likely to begin in late winter. However, most models show limited accuracy until early winter. La Niña and negative IOD events increase the chances of above-average rainfall across NSW in winter and spring.

Modelling of the NINO 3 region of the Pacific Ocean by AEGIC in early May indicated that the most likely analogue (similar) year to 2016 is still currently 1983 (neutral ENSO). Their modelling suggests ENSO-neutral conditions are the most likely outcome this month, with sea surface temperatures approaching La Niña thresholds in spring. They indicate a 60% likelihood of a La Niña event occurring later in the year, and a 30% chance of neutral conditions. The Bureau of Meteorology’s ENSO outlook history shows that 1983 trended from an El Niño event in summer 1982/83 (via La Niña watch and alert) into a La Niña event in late spring and summer 1983/84. The May to July and May to October periods in 1983 was wetter than average across most of NSW, and near-neutral across areas of the central and southern tablelands, Hunter valley, mid-north coast and far west.

During April, cloud conditions at the junction of the equator and International Date Line were above average, but have recently declined to near-average. While the 30-day SOI is moderately-strongly negative, it has risen consistently since late April and is expected to rise further towards neutral levels. Trade winds have remained mostly near-normal since early March.

Slightly warm sea surface temperature anomalies extended across most of the equatorial Pacific during April, although they continued to decline.  Temperatures in the NINO 1, 2 and 3 regions are now neutral. Warm anomalies in the NINO 3.4 and 4 regions are very shallow and in the NINO 3.4 region the temperature is just below the El Niño threshold. The cool anomaly has continued to strengthen, and extends across the equatorial Pacific at between 0-200 metres depth. It has reached the surface in the east. This with other indicators signals the possibility of a La Niña event.

Warm sea surface temperatures exist to the north of the continent, as well as to the north east and north west, and across much of the Indian Ocean. These areas remain potential sources of moisture for winter rainfall. The sub-tropical ridge moved further north during April and the southern annular mode became negative during mid-late month, which are positive signs for May rainfall.

Climatic outlook summary

NSW Seasonal Outlook (BoM)

Current outlook

Previous outlook

Quarterly Rainfall

Wetter

Wetter

(western NSW, western Riverina, central west, west of the central tablelands)

Near neutral

(north west, northern tablelands, south, south east and coast)

Quarterly Maximum Temperature

Warmer

(eastern and southern NSW, central tablelands, Hunter valley, eastern central west and areas of the northern tablelands and northern slopes)

Near neutral

(far west, south west, west of the central west, most of the north west)

Warmer

(eastern and northern NSW, north west, eastern Riverina, east of the central west)

Near neutral

(far west, south west, western Riverina, west of the central west)

Quarterly Minimum Temperature

Warmer

Warmer

El Niño Southern Oscillation (ENSO)

ENSO (overall)

El Niño (rapidly declining)

Trending to neutral this month, La Niña possible in winter/spring

El Niño (rapidly declining)

Trending to neutral or La Niña

BoM ENSO Outlook Status

La Niña watch

La Niña watch

SOI

Variable, currently moderately-strongly negative

Variable, currently slightly negative

Pacific Ocean (NINO3.4)

Borderline with neutral,

trending to neutral

(likely to be cool in winter/spring)

Slightly warm - warm,

trending to neutral

(possibly to cool in winter/spring)

Indian Ocean (IOD)

IOD neutral

(negative IOD possible in late winter)

Warm Indian Ocean sea surface temperatures

IOD neutral

(negative IOD possible in winter/spring)

Warm Indian Ocean sea surface temperatures

Southern Annular Mode (SAM/AAO)

Near neutral, possibly trending to moderately to strongly negative

Weakly positive, trending to neutral

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

Rainfall and temperature

During April, rainfall across the state ranged from 0-109 mm, with most of the state receiving 10-25 mm.  Most of inland NSW received little rainfall until the end of the month. The rainfall received was generally less than 20-60 per cent of normal.

Falls of less than 10 mm occurred across areas of the far west, north west, south west, southern and central tablelands, central west, Monaro and the upper Hunter valley. The best falls of more than 25-50 mm occurred across areas of the coast (particularly the north coast) and scattered areas of inland NSW.

Temperatures (particularly daytime temperatures) were well above average across most of NSW, with NSW recording the second warmest April on record.

Relative rainfall

Relative to historical records, rainfall during April was below average across 25 per cent of NSW, covering the eastern Riverina, south, south east, Sydney basin, Hunter valley, Liverpool plains and some areas of the far north east and north west. Above average rainfall was limited to areas of the central west and far west. The rainfall for much of the remainder of NSW ranged from about 30-50 per cent of normal.

Quarterly relative rainfall was below average across 75 per cent of NSW. Areas of near average relative rainfall were restricted to the far west, and some areas of the central west, Riverina and far south.

Soil moisture

Average modelled topsoil moisture remained at low levels across most of NSW during April, but improved by the end of month the in some areas of far western, central, southern and north eastern NSW. In early May, topsoil moisture levels improved further across much of inland NSW.

Relative to historical records, topsoil moisture during April was below average across most of the far north west, south, Riverina, central west, southern and central tablelands, southern highlands, Sydney basin, Hunter valley and areas of the northern tablelands, north west and north coast.

Modelled subsoil moisture levels declined slightly during the month, with the eastern areas of NSW showing the greatest decline. Relative to historical records, subsoil moisture remained near-average across most of the state, but was below average across areas of the north west, far north west, northern slopes, north-eastern central west, western Riverina, far south and areas of the southern, central and northern tablelands and the north coast. Above average relative subsoil moisture occurred across limited areas of the state, including areas of the far west, central NSW, central Riverina, Hunter valley and the far south east.

Streamflow

Yearly run off estimates remained low across many areas of NSW, but showed a high variability. Run off in the year to April remained low across most of the central and northern tablelands, areas of the southern tablelands, the north eastern and western areas of the central west and areas of the northern and south west slopes, north west, far west and far south. Areas of low run off also occurred in some areas of the north coast, upper Hunter valley and the south west slopes. Yearly run off remained high over areas of the south east, lower Hunter valley and central Riverina.

The Bureau of Meteorology's streamflow forecast indicates low streamflows are likely across most NSW monitoring stations during May to July. Near-median streamflows are likely at some south eastern locations, and near-median and low streamflows have a near-equal likelihood at some north eastern locations.

Relative pasture growth and biomass

Relative to historical records, AussieGRASS relative pasture growth during April was below average across much of the far north west, north west, northern central west, Hunter valley, Sydney basin, mid-north to north coast, central tablelands, Riverina, far south and areas of the south coast and southern tablelands. Growth across the remainder of NSW was near-average. There were large areas of missing data in the far west.

Other pasture growth models suggested a similar pattern, with additional areas of below average growth across the north coast and far south west. Limited areas of above average growth occurred in areas of the far west and the central west.

Over the quarter, AussieGRASS relative growth was below average across 62 per cent of the state. Areas of below average growth occurred across much of the far west, central west, western Riverina, north west, Hunter valley and areas of the northern tablelands and the mid-north to north coast. Above average growth was generally restricted to areas of the southern tablelands and south west slopes.

During April, relative biomass levels were below average across half of NSW. Areas of below average relative biomass extended throughout areas of the far west, north west, central west, western Riverina and the far south.

Figure 1: Relative monthly topsoil moisture

Map of the Relative Soil Moisture (Upper Layer) on average for April 2016

Figure 2: Relative quarterly pasture growth

Map of Pasture Growth relative to Historical Records from 1957; February 2016 to April 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 Australian Export Grains Innovation Centre, 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

Local Land Services On-ground Seasonal Conditions Reports

Bureau of Meteorology seasonal outlook

Bureau of Meteorology seasonal outlook video

Bureau of Meteorology El Niño Southern Oscillation (ENSO) wrap-up

Bureau of Meteorology El Niño Southern Oscillation (ENSO) outlook

International Research Institute for Climate and Society/NOAA Climate Prediction Centre ENSO forecast

NOAA Climate Forecast System (CFS) seasonal and monthly outlooks

Bureau of Meteorology rainfall totals, deciles, percentages and anomalies

AussieGRASS relative rainfall, pasture growth and biomass

CSIRO Australian Water Availability Project (soil moisture)

Queensland Alliance for Agriculture and Food Innovation (wheat and sorghum outlooks)

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 11 May 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 (11 May 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.