NSW State Seasonal Update - July 2023

Prepared by NSW DPI

NSW overview

The NSW DPI Combined Drought Indicator (CDI) shows 98% of NSW in the Non-Drought category at the end of July. Drought conditions are continuing to emerge on the North Coast, Hunter and the southeast of NSW. These regions are managing seasonal feed deficits that have arisen from low rainfall over the past 3-6 months. Producers continue to monitor on-ground conditions and climate forecasts closely, while implementing actions like supplementary feeding and stock reductions in line with their individual drought strategies.

Current conditions

• July rainfall was below average, variable, concentrated largely in central and southern NSW.
• Dry conditions continue to impact parts of the state leading to a decline in plant growth in the north, north-east, and south-east. On ground reports suggest that some areas are managing feed deficits.
• While only a small area of the state currently falls into one of the drought categories, there has been a recent decline in the drought indicators for some areas. The DPI continues to closely monitor conditions.
• July maximum temperature were high across NSW, with anomalies up to 1-3 ^oC above the long-term average. This is consistent with the extremely warm conditions being observed across the globe over the last 3-4 weeks.
• Subsoil moisture levels for NSW are mostly average to above average, generally drier in the north-east and far south-east of the state.
• Water availability for irrigated production remains adequate, with many irrigation storages at near full capacity.

Seasonal Climate Outlook

• Seasonal climate forecasts indicate increased likelihood of warmer than average daytime and overnight temperatures for most of NSW for the August to October period.
• Rainfall has an increased likelihood of being below average to well below average for most of NSW for the next three months.
• The ENSO Outlook status remains at El Niño ALERT. When El Niño Alert criteria have been met in the past, an El Niño event has developed around 70% of the time.
• The Indian Ocean Dipole (IOD) is currently neutral; models suggest a positive IOD event is likely in late winter to early spring. Long range forecasts of the IOD beyond September should be viewed with caution.

The CDI and its individual rainfall, soil moisture and crop/pasture growth metrics are leading biophysical indices of seasonal conditions and drought status. Other factors affecting production and economic responses usually lag the CDI. Further information about the correct interpretation of the CDI at a region and industry level is provided in the regional breakdown section of this report .

It is important to recognise the CDI provides an aggregated view of NSW, and that on-ground conditions can be different to those displayed in the maps. They provide an ‘on average’ view of a particular region only.

Rainfall

The rainfall anomaly data shows the difference between total monthly rainfall and the long-term average monthly rainfall (1981 – 2010; Figure 2a). Most of NSW has recorded a negative rainfall anomaly for July. Positive rainfall anomalies were recorded for small areas in the Western Local Land Services (LLS) region.

Rainfall was variable during July with most regions receiving between 10mm and 50mm of rainfall. The highest monthly rainfall totals (above 100mm) were recorded in the southern alpine regions of NSW. (Figure 2b). Large areas in the South East LLS region received less than 5mm of rainfall.

For the calendar year to date, eastern NSW has received between 200 to 600mm of rainfall. Areas around Coffs Harbour, Taree, Lismore and the southern highlands have received more than 600mm. West of the Great Dividing Range has generally received rainfall between 50mm and 400mm (Figure 2c). Year to date rainfall has been average to below average for most of NSW.

Temperature

Near average to above average maximum temperatures were experienced across most of NSW in July (Figure 3a). Maximum temperatures were generally between 1°C and 3°C above average. In July, the average maximum temperatures ranged from 0°C in the southern alps to above 21°C in north-eastern NSW (Figure 3b). Most of NSW ranged between 12°C and 21°C during July.

Minimum overnight temperatures were near average across most of NSW during July. Minimum temperatures were more than 1°C above average in the far northwest of NSW and some alpine regions (Figure 3c). Minimum temperatures were more than 1°C below average in parts of the North Coast LLS region. Minimum temperatures were generally between 0° and 6°C for most of NSW. The alpine region ranged between -3°C to 0°C. The warmest temperatures were along parts of coastal NSW and the far northwest of the state.

July 2023 saw an increase in the number of frost days experienced across the tablelands extending to the mid-west of NSW. This can slow or pause the growth of some productive pasture species. The alpine and northern tableland regions experienced the highest number of frost days during July (Figure 3e).

Normalised Difference Vegetation Index (NDVI) Anomaly

The seasonal Normalised Difference Vegetation Index (NDVI, Figure 4) indicates that plant greenness levels are variable across NSW. Many areas continue to have above normal plant greenness levels. Small, isolated patches of lower than average plant greenness are occurring across NSW. Regions where there more pronounced zones of normal to below normal greenness are the Central West, Hunter, North West, Murray and Western Local Land Services areas Some of the extremely negative NDVI areas (brown patches) are water bodies.

NSW Farm Dam Survey

The NSW Farm Dam Survey indicates dam levels are generally stable compared to the last Update (Figure 5). Higher farm dam levels are present across many parts of central, eastern and southern NSW. Low dam levels are evident along the NSW coast and hinterland. Large areas of Western NSW have dam levels below 60% capacity. Data is unavailable for some areas of NSW due to missing data.

Soil Water Index

The Soil Water Index (SWI, Figure 6) shows conditions continued to decline during July in northern NSW, the south east and Hunter. These areas have seen the Average and Below Average SWI category expand since the last Update. This is due to the continued low and variable rainfall received this year.

Plant Growth Index

The Plant Growth Index (PGI, Figure 7) shows that most of NSW remains in the Average to Above Average PGI category. The area in the Below Average category on the North Coast has expanded since the June Update. There is the potential that more areas will transition into the Below Average category during August.

Rainfall Index

The Rainfall Index (RI, Figure 8) shows that most of NSW remains in the Average to Extremely High category.  The area in the Below Average to Extremely Low categories has expanded since the June Update. This is confirmed by on ground reports that producers are managing feed deficits due to rainfall deficits and low stored soil water in parts of NSW.

Drought Direction Index

The Drought Direction Index (DDI, Figure 9) tracks the 150-day trend of daily rainfall totals. Western NSW is generally showing a wetting trend due to recent rainfall during May through to July. In contrast, much of eastern and northern NSW have recorded a strong drying trend during July. A weak drying trend has been recorded for most of central NSW. Areas in the Weak Drying Trend category have experienced a slightly drier June and July compared to previous months. The strong drying trend along the east coast and northern tablelands has been influenced by the high starting point for the trend, high rainfall recorded in late 2022 and the comparatively drier conditions over the last few months.

Changes in the individual drought indicators may have occurred since this update was released. For the most current information, please visit DroughtHub.

NSW outlook - July to September

(issued 3 August 2023)

Average to below average rainfall for much of NSW

• The seasonal rainfall outlook indicates that there is a 45% to 75% chance of below median rainfall across most of NSW during the August to October period (Figure 10).
• Parts of the Murray LLS region have a greater than 80% chance of below median rainfall over the next three months.
• Slightly above median rainfall is likely (55% to 65% chance) for a small region along the south coast of NSW.

High chance of warmer days for NSW

• The maximum temperature outlook indicates a more than 80% chance of exceeding median daytime temperatures across NSW during the August to October period (Figure 11).

Warmer nights across NSW

• There is an above 80% chance of warmer than median overnight temperatures across most of eastern, central and southern NSW during the August to October period (Figure 12).
• Across western NSW there is a 60% to above 75% chance of above median overnight temperatures.

Official national outlook

The official national outlook was released by the Bureau of Meteorology on 3 August 2023.

The rainfall outlook for August to October shows that most of Australia has a likely to very likely (60% to 80%) chance of below median rainfall. Above median rainfall is likely for parts of the Northern Territory, far North Queensland and parts of southern mainland Australia.

Maximum temperatures for August to October have a very likely chance (greater than 80%) of being warmer than average for most of Australia.

Minimum temperatures for the August to October period have a likely to very likely (60% to greater than 80%) chance of being warmer than average for most of Australia.

Forecast accuracy at this time of year has generally been moderate to high for most of Australia. The Bureau issues a new 3-month seasonal update weekly, each Thursday afternoon.

Global climate drivers

El Niño–Southern Oscillation (ENSO)

The Bureau of Meteorology’s El Niño-Southern Oscillation (ENSO) Outlook was released on 01 August 2023. The ENSO Outlook status is currently at El Niño ALERT.

Sea surface temperatures (SSTs) in the tropical Pacific Ocean are exceeding El Niño thresholds. However atmospheric indicators (E.g., trade winds, cloudiness) have not reached El Niño thresholds. The Southern Oscillation Index (SOI) is at neutral levels. This indicates that the Pacific Ocean and atmosphere have yet to become fully coupled, a criterion the Bureau uses to signify a full El Niño event.

Models indicate a high likelihood of further warming, with SSTs remaining above El Niño thresholds until at least the end of the year. The Bureau of Meteorology’s El Niño ALERT indicates a 70% chance of El Niño occurring in 2023.

Southern Oscillation Index

The 30-day Southern Oscillation Index (SOI; Figure 13) for the 30 days ending 30 July was -4.3. The 90-day SOI value was -7.9. Sustained negative values of the SOI below −7 typically indicate El Niño while sustained positive values above +7 typically indicate La Niña.

Sea surface temperatures (SST)

Monthly sea surface temperatures (SST) were warmer than average across most of the tropical Pacific Ocean (Figure 14). Warm SST anomalies persist in the southern Tasman Sea, from south-east Australia to New Zealand.

The latest values of the three NINO indices in the tropical Pacific for the week ending 30 July were: NINO3 +1.68 °C, NINO3.4 +1.05 °C, NINO4 +0.83 °C (sourced from the Bureau of Meteorology on 1 August 2023).

Persistent NINO3 or NINO3.4 values warmer than +0.8 °C are typical of El Niño, while persistent values cooler than −0.8 °C typically indicate La Niña.

Sub-surface sea temperatures

The four-month sequence of equatorial Pacific sub-surface temperature anomalies (to 27 July 2023) shows warm anomalies across most of the Pacific basin for the top 150m in depth (Figure 15). These warm anomalies reached more than 4^oC above average for the eastern Pacific and 2^oC in the western and central Pacific.

Indian Ocean (IOD)

The Indian Ocean Dipole (IOD) is currently neutral. The latest weekly value of the Indian Ocean Dipole (IOD) index to 30 July 2023 was +0.16°C.

All of the international climate models surveyed by the Bureau of Meteorology suggest a positive IOD event is likely to develop in late winter or early spring. A positive IOD occurs at values greater than +0.4 °C and can suppress winter and spring rainfall over much of Australia, including NSW. Long range IOD forecasts beyond September should be viewed with caution.

Southern Ocean (Southern Annular Mode – SAM)

The Southern Annular Mode (SAM) index is positive (as of 1 August) and is expected to return to neutral values in the coming weeks (Figure 16).

The Southern Annular Mode (SAM) refers to the north-south shift of rain-bearing westerly winds and weather systems in the Southern Ocean compared to their usual position. This indicator can be quite volatile and generally influences weather conditions on 1 to 3 week timescales. A neutral SAM has little influence on Australian rainfall.

CDI status for the regions

Figure 17 displays the CDI status for each individual Local Land Services (LLS) region to 31 July 2023. The following regional descriptions are based on data available until the end of July 2023.

Murray and Riverina regions

Murray and Riverina Regions production outlook remains strong

• The Riverina and Murray Local Land Services (LLS) regions remain in the Non-Drought category at the end of July (CDI, Figure 18).
• July rainfall was generally average to below average for most of the region.
• The seasonal NDVI anomaly data (Figure 19) shows that most of the Murray and Riverina regions were experiencing normal to higher than normal plant greenness levels for the May to July period. Lower than normal plant greenness is evident in eastern parts of the two LLS regions, and areas in the west. Some of the extremely negative NDVI areas (brown patches) represent water.

Drought indicators remain stable

• The Drought History charts (Figure 20) show the individual response of the drought indicators for Hay, Temora, Finley, and Moulamein.
• The indicators remain high at all locations and suggest a strong production outlook.
• To access a Drought History chart for your Parish, visit the Seasonal Conditions Information Portal.

The Combined Drought Indicator (CDI) is a tool that monitors drought conditions across NSW. The drought categories are based on assessing the response of three drought indicators: soil water, plant growth and rainfall. The indicators track the data over the past 12 months and show how the indices are tracking compared to long-term averages. The information provided in the map is aggregated to a Parish level and provides a regional assessment of conditions. Variability within and between farms is possible and this may not be reflected in the CDI map.

Western region

Western region producers should continue to monitor their seasonal conditions and forecasts closely in line with their production systems.

• The Combined Drought Indicator (CDI, Figure 21) shows that the Western LLS region is currently in the Non-Drought category.
• July rainfall was average for most of the Western region.
• The seasonal NDVI anomaly data (Figure 22) shows normal to above normal levels of plant greenness across the LLS region for the May to July period.
• Below normal levels of greenness continue in the north-west and northern areas of the LLS region. Some of the extremely negative NDVI areas (brown patches) represent water.

Continued decline in the drought indicators in some areas

• The Drought History charts (Figure 23) show the individual response of the drought indicators for Bourke, Ivanhoe, Wentworth, and Broken Hill.
• Although still high, the rainfall, soil water and plant growth indicators have continued to decline at Bourke.
• Indicators remain high at Ivanhoe and Wentworth, with a response to June rainfall seen at Broken Hill.
• To access a Drought History chart for your Parish, visit the Seasonal Conditions Information Portal.

The Combined Drought Indicator (CDI) is a tool that monitors drought conditions across NSW. The drought categories are based on assessing the response of three drought indicators: soil water, plant growth and rainfall. The indicators track the data over the past 12 months. This shows how the indices are tracking compared to the long-term averages. The information provided in the map is aggregated to a Parish level and provides a regional assessment of conditions. Variability within and between farms is possible and this may not be reflected in the CDI map.

North West, Northern Tablelands and North Coast regions

Drought Affected areas continue to increase, particularly in the North Coast region. Producers should monitor conditions and forecasts closely. Continue to assess management strategies and seek advice where needed to minimise impact on production and farm operations.

• The Combined Drought Indicator (CDI, Figure 24) shows most of the North West and Northern Tablelands regions in the Non-Drought category at the end of July.
• The North Coast region has seen conditions decline further around Grafton, Casino and Lismore since the June Update. Areas further south around Kempsey and Port Macquarie have also seen a decline in conditions.
• July rainfall was generally average to below average for the three Local Land Services regions and farm dam water levels are variable.
• The seasonal NDVI anomaly data (Figure 25) shows there is generally normal to above normal levels of plant greenness across eastern parts of the region and lower than normal levels of plant greenness across the western extent of the three regions. The NSW DPI continues to closely monitor conditions in these regions.

Drought Indicators are in decline in all regions consistent with the onset of a drought event

• The Drought History charts (Figure 26) show the individual response of the drought indicators for Tenterfield, Moree, Walgett, and Lismore.
• There has been a decline in the plant growth and soil water indicators at Moree. Indicators have continued to decline at Tenterfield, Lismore, and Walgett.
• To access a Drought History chart for your Parish, visit the Seasonal Conditions Information Portal.

The Combined Drought Indicator (CDI) is a tool that monitors drought conditions across NSW. The drought categories are based on assessing the response of three drought indicators: soil water, plant growth and rainfall. The indicators track the data over the past 12 months and shows how the indices are tracking compared to the long-term averages. The information provided in the map is aggregated to a Parish level and provides a regional assessment of conditions. Variability within and between farms is possible and this may not be reflected in the CDI map.

Central Tablelands, Central West, Hunter and Greater Sydney regions

Hunter Region producers should monitor their seasonal conditions and forecasts closely, continue to assess management strategies and seek advice where needed to minimise impact on production and farm operations.

• The Combined Drought Indicator (CDI; Figure 27) shows that the Central West, Central Tablelands and Greater Sydney Local Land Services (LLS) regions continue to experience Non-Drought conditions at the end of July.
• An increasing area in the Hunter LLS region has transitioned into the Drought-Affected category.
• July rainfall was below average for most of the Central Tablelands, Hunter and Greater Sydney LLS regions. Farm dam water levels are variable across the four LLS regions.
• The seasonal NDVI anomaly data (Figure 25) shows that large areas of the four LLS regions are experiencing normal to above average plant greenness. Parts of the Central West and Upper Hunter are experiencing below average levels of greenness for large areas of the for the May to July period. Some of the extremely negative NDVI areas (brown patches) represent water.
• NSW DPI continues to closely monitor conditions in these regions.

Drought Indicators continue to decline in the Hunter.  Other regions remain stable, indicating good production outlooks.

• The Drought History charts (Figure 29) show the individual response of the drought indicators for Cowra, Condobolin and Singleton.
• There has been a continued decline in the CDI indicators at Singleton however, the CDI indicators are currently high at all other locations.
• To access a Drought History chart for your Parish, visit the Seasonal Conditions Information Portal.

The CDI is a tool that monitors drought conditions across NSW. The drought categories are based on assessing the response of three drought indicators: soil water, plant growth and rainfall. The indicators track the data over the past 12 months and show how the indices are tracking compared to the long-term averages. The information provided in the map is aggregated to a Parish level and provides a regional assessment of conditions. Variability within and between farms is possible and this may not be reflected in the CDI map.

South East region

South East Region producers, particularly those on the east coast, should continue to monitor their seasonal conditions and forecasts closely. Continue to assess their management strategies and seek advice as needed.

• The Combined Drought Indicator (CDI, Figure 30) shows that most of the South East Local Land Services region is in the Non-Drought CDI category.
• The area that has transitioned to the Drought Affected category since the June Update has continued to expand.
• July rainfall was well below average for most of the region and farm dam water levels are variable.
• The seasonal NDVI anomaly data (Figure 31) shows near normal to above average levels of plant greenness across most of the region. There are areas that have below average levels of greenness. Some of the extremely negative NDVI areas (brown patches) represent water. The white patches represent missing data.
• The NSW DPI continues to closely monitor conditions in this region.

Drought indicators remain stable for inland areas, indicating a good production outlook. In contrast, the drought indicators are rapidly declining in parts of the coast and hinterland.

• The Drought History charts (Figure 32) show the individual response of the drought indicators at Bega, Cooma and Goulburn.
• Indicators remain steady at Cooma and Goulburn.
• There has been a continued decline in all indicators at Bega. Producers in the Bega region should monitor conditions in line with their production systems.
• To access a Drought History chart for your Parish, visit the Seasonal Conditions Information Portal.

The Combined Drought Indicator (CDI) is a tool that monitors drought conditions across NSW. The drought categories are based on assessing the response of three drought indicators: soil water, plant growth and rainfall. The indicators track the data over the past 12 months and shows how the indices are tracking compared to the long-term averages. The information provided in the map is aggregated to a Parish level and provides a regional assessment of conditions. Variability within and between farms is possible and this may not be reflected in the CDI map.

How does it work?

Much of the information in the Seasonal Conditions Report is sourced from the NSW DPI Enhanced Drought Information System (EDIS)™. The EDIS system is currently available in prototype form and is subject to an intensive ground truthing process. For more information, visit the interactive website via droughthub.nsw.gov.au.

EDIS is an ongoing project aimed at improving the quality and timeliness of efforts to monitor conditions across the state. Key features of the system are:

• It tracks drought by using four indicators; rainfall, soil water, plant growth, as well as tracing rainfall trends. Agronomic conditions have equal value to rainfall recorded at meteorological stations.
• The Combined Drought Indicator (CDI) brings this information together and has been designed to characterise developing drought conditions. The key purpose for building the CDI was as a drought early warning system.
• The rainfall, soil moisture and plant growth indicators in EDIS account for conditions over a 12-month window. This provides a compromise between a highly sensitive indicator (e.g. six months) and a less sensitive indicator (e.g. 24 months).
• Climate and remote sensing data drive the information system at a high resolution, but the CDI is reported at a Parish level.
• Because of its configuration and purpose, there will be differences to the indicator used in the National Drought Monitoring Framework (the Australian Rainfall Deficiency Analyser) which relies on rainfall alone.
• The CDI has three drought categories that characterise NSW according to drought intensity as well as the main drivers of a drought event (meteorological, hydrological and agronomic). DPI considers areas Drought Affected to be experiencing a drought event.
• The Drought Affected category encompasses a wide range of conditions from the very early stages of drought entry through to a drought event becoming intense. This enables the drought monitoring system to detect a drought event early. It is also possible to stay in the Drought Affected category for some period of time.

The way in which the indicators are combined to form the CDI is described in Table 1 below.

Table 1: Description of the Combined Drought Indicator framework

The NSW State Seasonal Update is provided each month by the NSW DPI Climate Branch.

Information used in this report was primarily sourced from the Australian National University, Australian Bureau of Meteorology, the US National Oceanic and Atmospheric Administration, the International Research Institute for Climate and Society (Columbia University), Geoscience Australia’s Digital Earth Australia Program, and NSW Department of Primary Industries.

Maps in this document contain data which is © Spatial Services – NSW Department of Finance, Services and Innovation (2023), Panorama Avenue, Bathurst 2795 and data which is © Commonwealth of Australia 2023, Australian Bureau of Meteorology, Melbourne, and © Australian National University. All rights reserved.

The seasonal outlooks presented in this report are obtained from the Australian Bureau of Meteorology and other sources (including World Meteorological Organisation Global Producing Centres). 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.

All climate and remote sensing input data is supplied to the Enhanced Drought Information System™ under the Australian Creative Commons Licence (CCY 4.0) and is made available by the Terrestrial Ecosystem Research Network.