NSW Seasonal Conditions Summary February 2015

Highlights

  • Rainfall during January was above average across most of NSW.
  • Over the last year, below average rainfall occurred over areas of the north west, northern tablelands, far north coast and Hunter valley. Severe rainfall deficiencies occurred across the north west and northern tablelands during the last 24 months.
  • Drier than normal conditions are likely between February and April across areas of the north west, northern central west central tablelands and far south west. There is a near-equal chance of drier or wetter than normal conditions across the remainder of NSW. Warmer than normal daytime temperatures are likely over most of NSW except areas of the south and far north east. Overnight temperatures are likely to be warmer in the north and along the coast.
  • Drier than normal conditions are likely during February, with warmer daytime temperatures across areas of north western, central and eastern NSW. Warmer overnight temperatures are likely across areas of the south east.
  • ENSO is neutral, with central and eastern Pacific sea surface temperatures declining. Neutral conditions are likely through autumn, although some indicators are still showing El Niño trends.
  • Topsoil moisture levels were stable across eastern and eastern-central NSW, and improved in the west. Subsoil moisture levels were generally stable, with improvements in the far north west, south east and north east.
  • Rainfall has continued to benefit the growth of lucerne and pastures. Yield prospects for dryland and irrigated summer field crops have improved. Follow up rainfall is still required, particularly for late sown dryland crops.
  • Resources to assist in management for areas suffering poor rainfall and growth are available at Managing drought.

Overview

Rainfall during January was above average across 77 per cent of NSW, and average to near average across 22 per cent. However, its distribution in some areas was variable due to thunderstorm activity, particularly in the north west. Below average rainfall was recorded over areas to the north west of Walgett and to the north east of Armidale.

Rainfall over southern, central and most of coastal NSW was generally well above average to extremely high. Areas of the north west, northern tablelands, central tablelands, Hunter valley and north coast received near average to average rainfall. In areas of the north west, rainfall was less than 60 per cent of normal.

Overall daytime temperatures for the month were below average across much most of NSW, except across the coast and areas of the adjacent tablelands, and an area between Bourke and the Queensland border. Overnight temperatures were above average across most of the State, particularly over the south of the State and the south to mid-north coast.

Over the last year, below average rainfall occurred over areas of the north west between Walgett, Goodooga, Collarenebri and Brewarrina. Rainfall was also below average over areas of the northern tablelands between Armidale and Tenterfield, areas of the mid-north coast between Newcastle and Taree and over the far north coast north of Lismore. Areas around Hay and to the south east of Balranald were also affected. Over the last 24 to 36 months, severe rainfall deficiencies occurred across the north west, northern tablelands and in the western Riverina around Hay.

The rainfall has continued to benefit summer-growing pastures and lucerne. It has greatly improved the yield prospects for dryland and irrigated summer field crops, particularly sorghum, sunflowers, soybeans, and cotton. Prospects were especially improved in those areas that received rainfall near crop flowering. Sugar cane crops along the north coast have also benefitted from consistent summer rainfall. Yield modelling by the Queensland Alliance for Agriculture and Food Innovation (QAAFI) suggests potential sorghum yields in northern NSW are close to average, and above average to the east of Moree and on the Liverpool Plains. Periods of cooler temperatures during January have reduced potential rice yields.

Follow up rainfall will be needed during the next two months to realise potential yields, particularly for late sown crops. Subsoil moisture reserves are still limited in many areas and the outlook suggests a return to drier and warmer than normal conditions over the next few months.

Control of summer weeds has been necessary on areas intended for winter cropping.

Good pasture growth continued during January across the tablelands, slopes, much of the coast and areas of the central west. Across most of the far west, pasture growth improved greatly. Pasture growth remained low to moderate across areas of the north west, the western Riverina and the northern central west.

Biomass levels improved across the east of the State, including the coast, tablelands and upper slopes, but remained low across much of north western and central NSW. The rainfall reduced the quality of standing dry feed, particularly across central and western areas. Supplementary feeding of stock is occurring in some areas.

The good rainfall has been insufficient in many areas to replenish stock water supplies, which is of concern given the likelihood of warmer daytime temperatures during February to April. Yearly streamflow analysis indicated below average run off over areas of the north west, central and northern tablelands, central west, Riverina, Hunter valley, the Sydney basin and areas of the north coast. Storm rainfall has resulted in run off in some of these areas, but not in others. Well below average streamflow has occurred across areas of the tablelands, Riverina, north west and central west over the last two years.

NSW Seasonal Conditions Report – February 2015

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Seasonal outlook

The latest Bureau of Meteorology seasonal outlook indicates a near-equal chance of drier or wetter than normal conditions between February and April across the majority of southern NSW, the north east and coast. Drier than normal conditions are likely across the north west, northern central west and areas of the central tablelands and far south west. However, the past accuracy for this outlook is low across western and most of southern NSW.

Warmer than normal daytime temperatures are likely across NSW during the period, except across areas of the far south and the far north eastern corner. The past accuracy for this outlook is moderate. Warmer overnight temperatures are likely over most of northern, north eastern and coastal NSW. This includes areas of the northern central west, the Hunter valley, the eastern and northern areas of the central tablelands, the central coast and the south east. There is a near-equal chance of warmer or cooler than normal conditions for the remainder of NSW. However, past accuracy is low for the overnight temperature outlook across most of NSW but moderate across areas of central, north wester and south eastern NSW.
During February, drier than normal conditions are likely across NSW, except across the far north eastern corner. In this area, there is a near-equal chance of drier or wetter than normal conditions. However, the past accuracy is low for this outlook over much of western, central and south eastern NSW. Warmer daytime temperatures are likely across much of central and north western NSW, the southern and central tablelands and the south to mid-north coast.

For the rest of the State, there is a near-equal chance of cooler or warmer than normal daytime temperatures. The past accuracy for this outlook is moderate across most of NSW. There is a near-equal chance of cooler or warmer than normal overnight temperatures across most of the State, although warmer than normal temperatures are likely in areas of the south east, central tablelands, central coast and the southern end of the Hunter valley. Cooler than normal overnight temperatures are likely in the far south west. The past accuracy for this outlook is low in the south west, north east and central tablelands, but moderate elsewhere.

More recent (unofficial) outlooks suggest warmer than normal daytime temperatures across most of NSW during February, and near normal overnight temperatures. Warmer overnight temperatures are likely in the south east and cooler overnight temperatures in the far north east.

During March, drier than normal conditions are likely in the southern, central and western areas of NSW. Warmer than normal daytime and overnight temperatures are likely across NSW. However, the past accuracy for these outlooks is low for rainfall across the northern half of NSW, and low across the State for the temperature outlooks.

The pasture growth outlook for NSW has not been provided. It has extremely low skill for NSW, due to the 'autumn predictability gap' in the accuracy of the Southern Oscillation Index (SOI).

El Niño Southern Oscillation (ENSO)

ENSO is currently neutral, with central and eastern Pacific sea surface temperatures declining and cloudiness at the International Date Line close to average. Enhanced rainfall has occurred across much of the 'Maritime Continent' area to the north of Australia. The Bureau of Meteorology's ENSO tracker status is currently 'neutral'.

Most indicators suggest a neutral outlook, but some are still showing El Niño tendencies (such as the eastwards movement of warm water in the sub-surface, the SOI and the thermocline slope index).
Sea surface temperatures have cooled in the eastern and central equatorial Pacific, but warm anomalies are still present across the western equatorial Pacific. The weekly sea surface temperature anomaly in the key (central) NINO3.4 region is currently +0.39°C (as at 1 February). The weekly sea surface temperature anomaly in the (eastern) NINO3 region is +0.10°C, but is +0.87°C in the (western) NINO4 region.

Sub-surface warm temperature anomalies have increased in the central Pacific and have moved eastwards, which may eventually result in surface warming. A cool anomaly remains in the eastern-central Pacific. The SOI has fallen since the late December to mid-January period, but has been stable over the last few weeks. It is currently -7.8 (as at 4 February). This recent fall is as a result of tropical weather near Tahiti. Fluctuations in the SOI are common at this time of year, and its accuracy as a climate signal is low.

Rainfall during January remained below average near the junction of the equator and International Date Line, and was above average across Indonesia. Trade winds were near average in the eastern equatorial Pacific, but weakened and reversed in areas of the west, possibly due to the passage of the Madden-Julian Oscillation into the western Pacific. Such a reversal sometimes occurs as a result of the weakening of an El Niño event. Other indicators such as the thermocline slope index also reflect a tendency towards El Niño conditions.

Eight global climate models suggest neutral conditions over the next few months (as at 1 February). They indicate somewhat warmer than normal NINO3.4 sea surface temperatures, but within the neutral range. Two models indicate further warming by June to above the Bureau of Meteorology's El Niño threshold, with a further two models close to the threshold. However, model accuracy is low at this time of year (the 'autumn predictability gap').

Climatic outlook summary

NSW Seasonal Outlook Current outlook Previous outlook
Quarterly Rainfall

Drier
(north west and areas of the central west and central tablelands and far south west)

Near neutral
(south, coast and north east)

Near neutral - neutral

Quarterly Maximum Temperature

Warmer

Near neutral
(areas of the far north east, far south and far south east)

Warmer

Near neutral
(far north east, areas of central/southern tablelands and south east)

Quarterly Minimum Temperature

Warmer
(most of northern and coastal NSW)

Near neutral – neutral
(southern and far western NSW)

Warmer

El Niño Southern Oscillation (ENSO)
ENSO (overall) Neutral  Neutral –
El Niño possible/likely
BoM ENSO Tracker Status Neutral El Niño Alert
SOI Neutral (currently negative) Neutral (currently weakly negative)
Pacific Ocean (NINO3.4) Neutral - slightly warm Slightly warm/warm
(Neutral – some models)
Indian Ocean (IOD) Neutral (currently negative) Neutral (currently slightly negative)
Southern Annular Mode (SAM/AAO) Weakly positive Weakly negative – weakly positive

Rainfall and temperature

A series of complex troughs resulted in storms and rainfall across much of NSW in early to mid January. Later in the month, onshore flow also generated locally heavy rain across the east coast. Rainfall across the State during January ranged between 5-600 mm, with most of the State receiving 50-200 mm. Rainfall was variable and generally below average (25 mm or less) across areas of the north west, particularly to the north west of Walgett. These areas received less than 40-60% of their normal rainfall.

Rainfall in across western NSW generally ranged from 25-100 mm, with an area near Fowler's Gap receiving more than 100 mm. The central areas of the State generally received 25-100 mm, with higher falls in areas of the north west to the east of Moree and Tamworth.

Rainfall across the tablelands ranged from 50-200 mm and most of the coast received 100-200 mm. The south and far north of the north coast received 200-300 mm or more, as did some of the alpine areas and isolated areas of the central and mid-north coast.

Daytime temperatures were 0.4°C cooler than average across NSW during January. Most of the inland areas were cooler than normal. Some areas were up to 8-12°C below average early-mid month. The coastal areas and an area between Bourke and the Queensland border had above average daytime temperatures. Overnight temperatures were 0.8°C warmer than average across NSW. Overnight temperatures were between 1-2°C above average across the south of the State and from the south to mid-north coast. An area around Tibooburra and extending from the Queensland border to Nyngan and Nymagee had generally below average overnight temperatures. In early January, overnight temperatures in the far west and south of NSW were 6-10°C above average. Over two periods late in the month, overnight temperatures across inland NSW were 2-6°C below average.

Relative rainfall

Relative to historical records, rainfall during January was above average across 77 per cent of NSW. Across the south and most coastal areas of the State, rainfall was well above average, with significant areas of the west and far south receiving extremely high relative rainfall.

Relative rainfall across the western half of the north west, the northern areas of the central west, areas of the central tablelands and much of the northern tablelands and northern Hunter valley was in the average range (that is, between the 30th and 70th percentile). Rainfall to the north west of Walgett and to the north east of Armidale was below average.

Quarterly relative rainfall was above average over 64 per cent of the State, including most of western, southern and coastal NSW. Relative rainfall was average across north western NSW and areas of the central west and northern tablelands. Below average relative rainfall was restricted to 1 per cent of NSW, primarily in an area around Goodooga.

Half yearly relative rainfall was average across 65 per cent of NSW, generally across the centre of the State. Above average relative rainfall occurred across 29 per cent of the State, extending across the far west (particularly the far north west) and along the coast and adjacent tablelands. Relative rainfall across large areas of the far west and the far south east was extremely high. Below average relative rainfall occurred over 6 per cent of NSW, particularly in areas of the north west, an area of the far south west near Balranald, near Hay and in the east of the Riverina.

Yearly relative rainfall was average across 63 per cent of NSW. Areas of below average relative rainfall for the period made up 8 per cent of NSW. They extended across the north west, northern tablelands, the far north coast and areas of the mid-north coast and Hunter valley. Below average relative rainfall also occurred across areas of the far south west and in the western Riverina near Hay and Balranald.

For the two years to January, well below average relative rainfall extended across much of the north west and northern tablelands. Other areas of below average relative rainfall occurred in the north of the central west, central tablelands and Hunter valley as well as over the eastern and western Riverina and far south west near Balranald. Areas of well below average low relative rainfall over the period occurred in the central tablelands around Mudgee, and in the Riverina around Hay. Areas of extremely low relative rainfall occurred across the north west between Goodooga, Walgett, Collarenebri, Coonabarabran and Narrabri, across the northern slopes and across the northern tablelands from Armidale to Glen Innes.

Soil moisture

Modelled topsoil moisture levels remained stable across eastern and eastern-central NSW during the January. Topsoil moisture levels improved slightly in the eastern and central Riverina, and increased over the north coast. Soil moisture across most of western and western-central NSW improved, but still remained in the low range. Levels in the north west between Bourke and Walgett showed little change, remaining low.

Relative to historical records, topsoil moisture was generally well above average across most of western and southern NSW, the south east and much of the coast. Relative topsoil moisture levels were also well above average to extremely high between Moree and Inverell. Levels were below average between Walgett, Lightning Ridge and Bourke.

Modelled subsoil moisture levels improved across the far west, and over areas of the far south east and north coast. Elsewhere, they showed little change.
Relative to historical records, subsoil moisture remained below average across much of the north west, northern tablelands, areas of the mid-north to north coast, areas of the central tablelands and areas of the Riverina. Subsoil moisture was extremely low across areas of the north west from Goodooga and Lightning Ridge to Collarenebri, Walgett, Narrabri and Coonabarabran. Other areas of extremely low subsoil moisture occurred over the northern tablelands between Armidale and Glen Innes and over the central Tablelands between Orange and Cowra. Subsoil moisture was above average in areas of the far west, and in the far south east of NSW.

Streamflow

Streamflow analysis over the last year indicated below average run off over areas of the north west, central and northern tablelands, central west, Riverina, Hunter valley, the Sydney basin and areas of the north coast. Storm rainfall has resulted in run off in some of these areas, but not in others. Well below average streamflow has occurred across areas of the tablelands, Riverina, north west and central west for the last two years.

Relative pasture growth and biomass

Relative to historical records, AussieGRASS modelled pasture growth improved across much of the west and south of the State between December and January. Relative growth in some areas of the coast was near average, and in other areas above average. Relative growth was below average over just 3 per cent of NSW, average over 26 per cent and above average over 43 per cent. However, there were large areas of missing data from the modelling, particularly in the west. Below average relative growth was restricted to areas of the north west and an area of the central west near Coonabarabran. Above average relative growth occurred across the southern and south-central areas of NSW, the tablelands and upper slopes and areas of the coast. Relative growth across other areas of the north west and northern central west was near average.

Other pasture growth models indicated well above average growth from temperate pasture species across most of western and southern NSW, the coast and the tablelands. Over north western NSW, areas on the eastern and north eastern edges showed above average growth. The only areas of below average growth occurred in the north west between Walgett and Brewarrina. Average growth occurred across elsewhere in the north west, as well as across areas of the mid-north to north coast. Areas of extremely high relative pasture growth occurred over areas of the far west, the central and southern Riverina, the southern areas of the central west, the northern tablelands, Hunter valley and most of the south east. For tropical pasture species, the best growth occurred across the central to north coast, the coastal strip of the south east, and areas of far western NSW to the north of Broken Hill.

Over the three months to January, relative growth improved greatly across most of NSW. Approximately 32 per cent of NSW had above average relative growth, a major increase from 3 per cent in the previous quarterly period. Below average relative growth declined to 15 percent of NSW, from 59 per cent in the previous period. Relative growth remained low for the period across much of north western NSW, and in areas of the central west (particularly the north) and the central Riverina. Relative growth was generally above average across the far west and across the tablelands and Monaro. It was average elsewhere.

Over the six months to January, relative growth remained low across the central and southern areas of NSW, average across most of the west, and above average across the tablelands, coast and far north west.

Relative biomass levels remained high or improved across the tablelands, coast and across the far north west. In these areas, relative biomass was above average to extremely high. Relative biomass levels remained low across the north west, the east and south of the central west and the Riverina. Levels were average elsewhere. Some 75 per cent of NSW had average or above average relative biomass levels.

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.

Acknowledgments

Information used in this report was sourced from the Bureau of Meteorology, CSIRO, Queensland Department of Science, Information Technology, Innovation and the Arts, NSW Local Land Services, the US National Oceanic and Atmospheric Administration, the International Research Institute for Climate and Society (Columbia University) 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 6 February 2015.

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 (6 February 2015). 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.