NSW State Seasonal Update - August 2022

Prepared by NSW DPI

NSW overview

Following a dry July, August rainfall was average to above average for most of NSW, except along the coast where below average rainfall was recorded. The NSW DPI Combined Drought Indicator (CDI) shows 100% of the state in the Non-Drought category at the end of August. Conditions remain generally wet across the state with high soil moisture. Many on farm and major water storages are full. Due to the saturated landscape the risk of flood remains throughout NSW.

Soil water, plant growth, and rainfall indices have remained high across the state in August. However, persistent wet conditions and average temperatures continue to present challenges for quality pasture production, on-ground management of crop pests and diseases, and maintaining animal health and welfare.

Water availability for production remains strong, with high on-farm dam levels across much of the state and irrigation schemes are at full capacity.

Climate forecasts indicate cool wet conditions are expected to continue across NSW this Spring. The latest Bureau of Meteorology (BoM) Seasonal Outlook indicates moderately high to very high chances of above median rainfall across NSW for the three months between September and November. The ENSO Outlook status is currently at La Niña ALERT, as four of the seven climate models suggest that La Niña may re-form early to mid-spring and continue through to December. The Indian Ocean Dipole (IOD) is negative, increasing the likelihood of above average spring rainfall across Australia. A persistent positive Southern Annular Mode (SAM) indicates that Antarctic south westerly winds are currently in a position where they influence NSW climate, further increasing the likelihood of rainfall across eastern NSW.

The CDI and its individual rainfall, soil moisture and crop/pasture growth metrics are leading biophysical indices of drought. 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 (1961-1990; Figure 2a). Above average rainfall has been received across most of NSW in August, excepting along the coast where the lowest negative rainfall anomalies were recorded. The highest positive rainfall anomalies occurred in the southern Tablelands and alps.

The higher rainfall totals were recorded in the eastern Riverina and Murray LLS regions where rainfall of more than 200mm has been received (Figure 2b). Areas of the Western, North Coast and South East LLS regions have received less than 25mm of rainfall. For the calendar year to date coastal NSW has received between 600mm to above 2000mm of rainfall. Rainfall west of the Great Dividing Range has totalled between 100mm and 1000mm (Figure 2c). Year to date rainfall has been average to above average for most of NSW and very much above average for coastal NSW.

Temperature

Average maximum temperatures were experienced across most of NSW in August (Figure 3a). Slightly above average maximum temperatures were experienced in pockets in the far west, central and southern NSW. Slightly below average maximum temperatures occurred in northern and central NSW. The average August maximum temperatures ranged from 0°C in the southern alps up to 24°C in northern NSW. Areas west of the Great Dividing Range had maximum temperatures above 12°C, and above 18°C for north western areas of NSW (Figure 3b).

August minimum temperatures for NSW were average to above average for most of NSW with some areas of western NSW and the North Coast experiencing slightly below average minimum temperatures (Figure 3c). The average August minimum temperatures were above -3°C in south eastern NSW and above 6°C in the west (Figure 3d). Minimum temperatures in the Tablelands ranged from -3 to above 3°C. The number of frost days in August were fewer than in July and mostly concentrated in the Tablelands and alps (Figure 3e).

Normalised Difference Vegetation Index (NDVI) Anomaly

The seasonal Normalised Difference Vegetation Index (NDVI, Figure 4) indicates that plant greenness levels are close to normal, to well above normal across most of NSW for the June to August period. Slightly lower than normal plant greenness remains evident across parts of the North West and Central West LLS regions. Levels of plant greenness have noticeably improved in western NSW. 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 greater than 60% of capacity across NSW (Figure 5). Parts of the Western, Riverina and Murray LLS regions of NSW maintain farm dam levels at less than 20% of capacity. Data is unavailable for some areas of NSW due to cloud cover this past month.

Soil Water Index

The Soil Water Index (SWI, Figure 6) indicates the majority of NSW is currently in the above average category. Areas of the Western, Riverina, Murray and Central West LLS regions previously in the average category have moved into the above average soil water category due to the above average rainfall received in August. Despite below average rainfall along the coast, large areas of north eastern and south eastern NSW are in the extremely high category due to continued rainfall on saturated landscapes and average temperatures experienced in these areas in August. Central NSW also has areas in the extremely high category due to above average rainfall and average temperatures in August.

Plant Growth Index

The Plant Growth Index (PGI, Figure 7) indicates that the majority of NSW is in the above average category at the end of August. Parts of Western, Riverina, Murray, Central West and North West LLS regions previously in the average category have moved to the above average plant growth category, reflecting the soil water index and the wetter August period. Some areas of south-eastern NSW in the extremely high category also reflect the SWI.

Rainfall Index

The Rainfall Index (RI, Figure 8) indicates that at the end of August most of NSW is in the above average category or extremely high categories. However, the above average rainfall received in August for areas west of the Great Dividing Range has resulted in more of the Western, North West, Riverina and Murray LLS regions moving into the above average RI category. Most of central and eastern NSW is currently in the extremely high category; this reflects the distribution of above average rainfall accumulated over the last 12 months.

Drought Direction Index

The Drought Direction Index (DDI, Figure 9) tracks the 150-day trend of daily rainfall totals. The DDI indicates a strong drying trend along the north and south coasts, the Central West and large areas of the Western LLS region. Weaker drying trends can be seen throughout parts of western, northern and southern NSW reflecting the below average rainfall received in these areas in July, despite the average to slightly above average rainfall in August. The drying trends are a result of extremely high rainfall recorded in late summer and early Autumn of 2022 and the comparatively drier conditions in the recent months. Importantly the weak to strong drying trend does not indicate the emergence of a drought in the regions, rather it indicates a degree of drying following on from the very wet summer and autumn. The above average rainfall received throughout the Tablelands in August has supported the wetting trends shown in these areas.

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

CDI status for the regions

Figure 10 displays the CDI status for each individual Local Land Services (LLS) region to 31 August 2022. The following regional descriptions are based on data available until the end of August 2022.

Murray and Riverina regions

The Combined Drought Indicator (CDI, Figure 11) shows that all of the Riverina and Murray Local Land Services (LLS) regions are in the Non-Drought category at the end of August.

The seasonal NDVI anomaly data (Figure 12) shows that most of the Murray and Riverina regions were experiencing average to above average levels of plant greenness for the June to August period. White areas are missing data due to cloud cover.

The time series charts (Figure 13) show the individual response of the drought indices for Hay, Temora, Finley, and Moulamein. Recent conditions have helped Temora maintain average to high soil water, plant growth and rainfall indices. Following the drop in all three drought indicators due to dry weather in July, average August rainfall and slightly warmer temperatures have seen them lift again for Hay, Finley, and Moulamein, with these areas remaining the Non-Drought category. Further rainfall is required in these areas to maintain the Non-Drought category. To access a time series for your Parish, visit the Combined Drought Indicator website.

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

The Combined Drought Indicator (CDI, Figure 14) shows that all of the Western LLS region is in the Non-Drought category. The seasonal NDVI anomaly data (Figure 15) shows normal to high levels of plant greenness across the Western LLS region for the June to August period.

The time series charts (Figure 16) show the individual response of the drought indices for Bourke, Ivanhoe, Wentworth, and Broken Hill. Average to above average rainfall throughout the region in August has produced average to high soil water, plant growth, and rainfall indices at all locations; this is a slight increase in indices following the drier weather in July. NSW continues to monitor the Western LLS region closely. To access a time series for your Parish, visit the Combined Drought Indicator website.

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

The Combined Drought Indicator (CDI, Figure 17) shows that the North West, Northern Tablelands and North Coast Local Land Service regions are in the Non-Drought category.

The seasonal NDVI anomaly data (Figure 18) indicates near to above-normal greenness across most of the regions for the June to August period. Parts of the North West have average to slightly below average levels of greenness.

The time series charts (Figure 19) show the individual response of the drought indices for Moree, Walgett, Tenterfield and Lismore. The indicators remain high at all locations. To access a time series for your Parish, visit the Combined Drought Indicator website.

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

The Combined Drought Indicator (CDI; Figure 20) shows that the Central West, Central Tablelands, Hunter and Greater Sydney Local Land Services (LLS) regions continue to experience Non-Drought conditions at the end of August. Despite below average rainfall in August, flood risks remain for parts of the regions due to the saturated nature of the landscape and full water storages. The NSW DPI continues to closely monitor conditions in these regions.

The seasonal NDVI anomaly data (Figure 21) shows near normal to very high levels of plant greenness across most of the LLS regions for the June to August period.

The time series charts (Figure 22) show the individual response of the drought indices for Cowra, Condobolin and Singleton. The CDI indicators remain high at all locations. Parts of these regions experienced above average rainfall in August and the challenges of managing agronomic pests and diseases, and maintaining animal health and welfare in saturated conditions persist. To access a time series for your Parish, visit the Combined Drought Indicator website.

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

The Combined Drought Indicator (CDI, Figure 23) shows that the South East Local Land Services region is in the Non-Drought CDI category. Below average rainfall was received in parts of the region in August however, due to the saturated nature of the landscape and cooler temperatures, the challenges of agricultural crop management and maintaining animal health and welfare in cool wet conditions persist. The NSW DPI continues to closely monitor these regions.

The seasonal NDVI anomaly data (Figure 24) showed near normal to high levels of plant greenness across most of the region for the June to August period.

The time series charts (Figure 25) show the individual response of the drought indices at Bega, Goulburn and Cooma. The three regions remain in the Non-Drought category with high soil water, plant growth and rainfall indices. To access a time series for your Parish, visit the Combined Drought Indicator website.

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.

Official national outlook

The official national outlook was released by the Bureau of Meteorology (BoM) on 1 September 2022. Rainfall during September to November is likely to be above median for eastern and central Australia. The risk of flooding remains high for eastern Australia due to high soil moisture, high stream flows, and predicted above median rainfall.

Maximum temperatures are likely to be cooler than average for central and eastern Australia during the September to November period. Tasmania, northern and south west Australia are likely to be warmer than median. Minimum temperatures for September to November are likely to be above median across Australia, although minimum temperatures could be equally warmer or cooler from the New South Wales central coast to south east Queensland.

The Bureau issues a new 3-month seasonal update weekly, each Thursday afternoon.

NSW outlook

NSW has a 70% to above 80% chance of receiving above median rainfall between September and November. Parts of the North Coast have a slightly lower forecast of 65% chance of above average rainfall between September and November (Figure 26).

The maximum temperature outlook indicates a less than 30% chance of warmer than median temperatures across most of NSW. There is a 50% to 60% chance of above median maximum temperatures in parts of south eastern NSW (Figure 27).

There is a 70% to above 80% chance of warmer than median overnight temperatures across southern and western NSW. North eastern NSW has a less than 50% chance of warmer overnight temperatures (Figure 28).

Global climate drivers

El Niño–Southern Oscillation (ENSO)

The Bureau of Meteorology’s (BoM) El Niño-Southern Oscillation (ENSO) Outlook was released on 30 August 2022. ENSO indicators are neutral however some atmospheric indicators, such as the SOI and cloudiness near the Date Line, are more La Niña-like. Four of the seven climate models suggest that La Niña may re-form this Spring and continue through to December. The ENSO Outlook status is currently at La Niña ALERT indicating three times the normal chance of La Niña returning in 2022.

Southern Oscillation Index

The 30-day Southern Oscillation Index (SOI; Figure 29) for the 30 days ending 28 August was +8.2. The 90-day SOI value was +11.4. 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)

Sea surface temperatures (SST) were cooler than average along the equator in the tropical Pacific Ocean and along the South American coastline. Warmer than average SSTs continue around the Maritime Continent and northern Australia (Figure 30).

The latest values of the three NINO indices in the tropical Pacific for the week ending 28 August were: NINO3 -0.3 °C, NINO3.4 -0.7 °C, NINO4 -0.5 °C.

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.

Sea sub-surface temperatures

The four-month sequence of equatorial Pacific sub-surface temperature anomalies (to 25 August 2022) shows cool anomalies to 150m depth in the central and eastern equatorial Pacific Ocean (Figure 31). Warm anomalies between 100m and 250m depth persist west of the International Date Line but less extensive in easterly extent than seen in previous months.

Indian Ocean (IOD)

The Indian Ocean Dipole (IOD) is negative. All five international climate models surveyed by the Bureau of Meteorology indicate that the negative IOD will continue through November. A negative IOD increases the likelihood of above average winter-spring rainfall and cooler days for eastern Australia. The latest weekly value of the Indian Ocean Dipole (IOD) index to 28 August 2022 was -0.8 °C.

Southern Ocean (Southern Annular Mode – SAM)

The Southern Annular Mode (SAM) index is strongly positive (as of 30 August) and is expected to remain generally positive throughout spring and early summer (Figure 32). A positive SAM has a drying influence on parts of south-east Australia but increases the chance of rainfall in eastern NSW.

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 the usual position. This indicator can be quite volatile and generally influences weather conditions on 1-3 week timescales.

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 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 (2022), Panorama Avenue, Bathurst 2795 and data which is © Commonwealth of Australia 2022, Australian Bureau of Meteorology, Melbourne. 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.