NSW Seasonal Conditions Summary April 2016

Highlights

  • Rainfall during March was slightly below to near average across most of NSW, but was variable and its effectiveness was limited by very warm conditions.
  • The rainfall outlook for April to June indicates wetter conditions are likely across western NSW, areas of central NSW and the western Riverina. There is a near equal chance of drier or wetter than normal conditions across the rest of NSW. Warmer temperatures are likely for most of NSW.
  • During April, there is a near equal chance of drier or wetter than normal conditions across most of NSW, with drier conditions likely in areas of the far south. Warmer than normal temperatures are likely.
  • The El Niño event has declined to a weak-moderate level, with sea surface temperatures continuing to decrease and strengthening cooler subsurface temperatures. Neutral conditions are likely to follow in autumn or winter. The possibility of La Niña and negative IOD events in winter-spring has increased. The Bureau of Meteorology’s ENSO outlook is now at La Niña watch.
  • Topsoil moisture levels declined during March, due to variable rainfall and above average temperatures.
  • Pasture growth and biomass declined. Supplementary feeding has been necessary to maintain stock condition in many areas.
  • Interest in dual purpose winter crops remains high, but sowings have been delayed by inadequate rainfall and soil moisture in most areas. Establishing crops require follow up rainfall. Good general rainfall is needed for winter crop sowing to fully commence and to ensure reasonable pasture and forage crop production during winter.
  • Yields of later sown dryland sorghum crops have been average, with irrigated summer crop yields generally above average .

Overview

Rainfall during March was below average across 27 per cent of the state. Most of NSW received slightly below average to near-average rainfall although falls in many areas were light, variable and patchy. Much of the rainfall across inland NSW occurred mid and late month. Temperatures were above average, particularly in the first two weeks of the month, which limited rainfall effectiveness.

Following a dry and hot February, lack of effective rainfall caused significant declines in pasture production. Particular declines in growth occurred across areas of northern and north eastern NSW, the central west and much of the coast. Growth across much of the far west and the south west remained low.

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

Biomass levels declined across most of NSW, particularly across areas of the north west, slopes, tablelands and coast.

Stock condition remains generally good, however in many inland areas supplementary feeding has been necessary to maintain stock condition due to lack of green feed and biomass.

Sowings of dual purpose winter crops remain limited, due to variable and patchy rainfall together with above average temperatures and limited topsoil moisture. Establishing crops are suffering from moisture stress. Interest in dual purpose crops remains high, particularly with the decline dry feed reserves and some dry sowing has occurred. Good general rainfall is necessary to allow winter crop sowings to properly commence, to replenish soil moisture reserves and to promote establishment of dry sown crops. A late autumn break will delay sowing and limit winter forage production, as well as restricting pasture production.

Yields of late sown dryland sorghum crops have generally been close to average. In the south, harvesting of rice and maize is nearly complete, with yields generally above average. Cotton harvesting is underway in the northern and central areas of NSW and soon to commence in the south. Above average yields are expected for irrigated crops.

Modelled topsoil moisture declined across most of NSW during March. Levels were generally well below average across much of northern, north western and central NSW as well as across the tablelands and much of the coast.  Levels in the south were slightly low, but above average in areas of the eastern Riverina and far west. By the end of the month, levels had improved in some areas.

Subsoil moisture levels also declined slightly, particularly in areas of the coast. Levels were below average across areas of the north west, northern tablelands and north coast, central tablelands and far south.

Stock water supplies continued to decline in many areas, with the added complication of algal blooms in dams and waterways. Areas of some concern are in the west of the central and southern tablelands, the northern tablelands, the northern slopes, the west and north east of the central west, the upper Hunter valley and areas of the north west and far west.

NSW Seasonal Conditions Report – April 2016

Download a copy of the NSW Seasonal Conditions Report for April 2016 (PDF, 3.8 MB)

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 April to June indicates wetter than normal conditions are likely across western NSW, the west and north of the Riverina, the central west and the western half of the central tablelands. There is a near-neutral outlook for the coast, most of the north west, the northern tablelands and southern NSW. This means there is a near-equal chance of drier or wetter than normal conditions in these areas. Warmer than normal daytime temperatures are likely across eastern, northern and central NSW for the period, and much of the south. There a near-neutral outlook for daytime temperatures across areas of the far west, far south west and western areas of the central west. Overnight temperatures are likely to be warmer than normal across NSW.

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

The NOAA Climate Forecast System (CFS) rainfall outlook for April to June is near-neutral for most of the state, with slightly wetter than normal conditions possible in areas of the far west. Warmer than normal conditions are likely for most of NSW, especially across the north, north east and along the coast. For April and for May, the NOAA CFS rainfall outlook is near-neutral across NSW and temperatures are likely to be warmer than normal, particularly in the north, north east and along the coast.

A survey of the major climate models in late March indicated most favour a wetter or near-neutral rainfall outlook for April-June. The rainfall outlook is reasonably consistent with that of the Bureau of Meteorology.

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

April - June

6

5

2

10

2

0

May - July

5

4

0

7

2

0

The AussieGRASS pasture growth outlook has very poor accuracy at this time of year. Historically, skill levels for the outlook are low autumn, and the outlook should therefore be regarded with caution. For April to June, the outlook suggests below average to average growth in the west, with some areas of above average growth in the far west. The outlook for growth in the western Riverina is suggested to be below average, with the east having above average growth. The outlook for the central west and the north west is suggested to be generally average, with some areas of below average growth. The slopes, southern tablelands, areas of the northern tablelands and the west of the central tablelands are suggested to have above average growth. Below average growth is suggested for areas of the coast, Monaro, Hunter valley, the west of the central tablelands and central areas of northern tablelands. However, this may be an artefact of the growth model. The seasonal rainfall prediction that the growth outlook is based upon is near-neutral for most of NSW. This was based on a consistently negative SOI during February and March. The rainfall outlook is reasonably consistent with to slightly less than that of the Bureau of Meteorology

El Niño Southern Oscillation (ENSO)

The Pacific Ocean remained in a weak to moderate El Niño event during March and early April, with warm sea surface temperatures in the NINO 3 and 3.4 regions continuing their decline and cool subsurface temperatures strengthening and expanding to within 50 metres of the surface.

Most modelling suggests that the El Niño event is likely to end in autumn or early winter. Global climate models are now almost equally split between the likelihood of a return to neutral conditions during winter or La Niña conditions during winter-spring. Due to this, the Bureau of Meteorology has moved its ENSO outlook status from El Niño to La Niña watch. A number of models also indicate the possibility of a negative Indian Ocean Dipole (IOD) event occurring in late winter or early spring. La Niña and negative IOD events increase the chances of above-average rainfall across NSW in winter and spring. However, model accuracy is low in the autumn and does not improve till early winter.

Modelling of the NINO 3 region of the Pacific Ocean by AEGIC in early April indicated that the most likely analogue (similar) year to 2016 is currently 1983 (neutral ENSO). Their modelling suggests ENSO-neutral conditions are the most likely outcome for the remainder of 2016. 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 April to June period in 1983 was wetter than average across most of NSW.

The equatorial Pacific sea temperatures and cloud conditions still remain consistent with an El Niño event although temperatures are declining rapidly and cloud levels have recently declined to just above average.  The 30-day SOI is just below neutral, but tends to be variable during the monsoon season and is of limited use as an indicator till about May. Trade winds have been mostly near-normal since mid-January, which is a sign of a declining El Niño event.

Warm sea surface temperature anomalies extend across most of the equatorial Pacific, although temperatures in the central and central-eastern areas are continuing to decline and are now restricted to a very shallow depth. A cool anomaly below this has continued to strengthen, and currently extends across the equatorial Pacific at between 50-250 metres depth. This with other indicators signals the decay of the El Niño event, and the possibility of a developing 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 autumn rainfall. The sub-tropical ridge was further south than normal during March and this combined with a moderately to strongly positive southern annular mode during March has tended to restrict frontal activity across NSW.

Climatic outlook summary

NSW Seasonal Outlook (BoM) Current outlook Previous outlook
Quarterly Rainfall Wetter
(western NSW, western Riverina, central west, west of the central tablelands)
Near neutral
(north west, northern tablelands, south, south east and coast)
Near neutral
(most of NSW)
Wetter
(south west and areas of the south, north west and northern central west)
Quarterly Maximum Temperature 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)
Warmer
(most of NSW)
Near neutral
(far western NSW)
Quarterly Minimum Temperature Warmer Warmer
El Niño Southern Oscillation (ENSO)
ENSO (overall) El Niño (rapidly declining)
Trending to neutral or La Niña
El Niño (declining)
Trending to neutral in winter
BoM ENSO Outlook Status La Niña watch El Niño
SOI Variable, currently slightly negative Variable, currently strongly negative
Pacific Ocean (NINO3.4) Slightly warm - warm,
trending to neutral
(possibly cool in winter/spring)
Warm
(above El Niño thresholds) but declining
Indian Ocean (IOD) IOD neutral
(negative IOD possible in winter/spring)
Warm Indian Ocean sea surface temperatures
IOD neutral
(currently variable)
Warm Indian Ocean sea surface temperatures
Southern Annular Mode (SAM/AAO) Weakly positive, trending to neutral Weakly - moderately positive

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

Rainfall and temperature

During March, rainfall across the state ranged from 1-475 mm with most of the state receiving 10-50 mm. However, the rainfall received was less than 60-80 per cent of normal across much of NSW and falls were variable in many areas due to localised showers and thunderstorms. Much of the rainfall across inland NSW occurred mid and late month.

Falls of generally less than 25 mm occurred in areas of the west, north west, western Riverina, central west and upper Hunter valley. Areas of the north west, central west and far west received less than 10 mm. Most of the tablelands, south west and areas of the central west received 25-50 mm. Coastal areas and the far south east generally received 50-100 mm, with the far north east receiving more than 100 mm. Some areas of the south coast received less than 50 mm, with areas of the mid-north coast receiving less than 25 mm.

Temperatures were well above average across most of NSW, generally being high in the first two weeks of the month but closer to normal in the last two weeks. This limited rainfall effectiveness.

Relative rainfall

Relative to historical records, rainfall during March was average across 61 per cent of NSW. Areas of below average relative rainfall occurred across 27 per cent of NSW, including areas of the Sydney basin, central to mid-north coast, and the southern half of the north coast.  Other areas of below average rainfall occurred across the areas of the northern tablelands, Hunter valley, north west, the northern central west and the south coast. Above average rainfall was limited to areas of the far west, the far north east and limited areas of the south east and eastern Riverina. Most of western and southern NSW had slightly below to near-average relative rainfall for the period.

Quarterly relative rainfall was average across 63 per cent of NSW but below average for 28 per cent. Areas of below average relative rainfall extended across most of the north coast, northern tablelands and areas of the northern slopes, north west and far west. Above average rainfall for the period was generally restricted to areas of the far south east, Sydney basin and lower Hunter valley.

Soil moisture

Average modelled topsoil moisture declined across most of NSW during March. Declines in topsoil moisture occurred across the south east, Sydney basin, lower Hunter valley and mid-north to lower north coast. Levels across inland NSW also declined, particularly across the north west, central west, central tablelands and northern tablelands. Relative to historical records, topsoil moisture during March was below average across most of the north coast, north west, northern tablelands, central west, Hunter valley, Sydney basin and areas of the southern highlands, southern and central tablelands and the Illawarra. Levels were above average in the far west. By the end of the month, levels had improved somewhat in areas of the north east, north west and far west.

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

Streamflow

Yearly run off estimates declined, but showed a high variability. Many areas are reporting low stock water levels. Run off in the year to March remained low across the north and west of the central tablelands, as well as north eastern and western areas of the central west and areas of the northern 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, south west slopes and the central and northern areas of the northern tablelands. Run off was high over areas of the south east and areas of the central coast, lower Hunter valley and central Riverina.

The Bureau of Meteorology's streamflow forecast indicates low streamflows are likely across most NSW monitoring stations during March to May. Near-median streamflows are likely at south eastern and some central coast, far north coast and southern monitoring stations.

Relative pasture growth and biomass

Relative to historical records, AussieGRASS modelled pasture growth declined during March across much of NSW. Below average growth occurred in areas of the far north west, north west, central west, northern tablelands, Hunter valley, Sydney basin, Illawarra and much of the north coast. Areas of the south east, central tablelands and western Riverina also had below average growth. Growth was generally average across the south of the state and the eastern Riverina. Limited areas of above average relative growth occurred across some of the south east, eastern Riverina and far south. There were large areas of missing data in the far west.

Other pasture growth models suggested generally average growth for the south, eastern and central Riverina, Monaro, southern tablelands, areas of the central tablelands and much of the far west. However, well below average to extremely low relative growth occurred across the north, north west, northern tablelands, central west, western Riverina, Hunter valley, Sydney basin, Illawarra and areas of the north coast and central tablelands. Limited areas of above average growth occurred in areas of the far west and the far south east.

Over the quarter, AussieGRASS relative growth was average across 52 per cent of the state but below average over 34 per cent. Areas of below average growth occurred across much of the far west, western Riverina, and the mid-north to north coast. Above average growth was generally restricted to areas of the southern and central tablelands, eastern Riverina, south west slopes and the Illawarra, south coast and Monaro.

During March, relative biomass levels declined, but remained average across about half of NSW. Areas of below average relative biomass increased in the far west and areas of the far south, and throughout areas of the north west, central west, western Riverina and areas of the north east.

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 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

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 12 April 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 (12 April 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.