NSW State Seasonal Update - April 2022

Prepared by NSW DPI

NSW overview

New South Wales continues to experience strong production conditions as a result of average to above average rainfall across most of the state this past month. Most of NSW is currently in non-drought with the NSW DPI Combined Drought Indicator (CDI) showing more than 99% of NSW in the Non-Drought category at the end of April.

Average to high soil moisture and recent rainfall have helped to maintain ground cover, high pasture availability, and in some areas deliver an early autumn break to the cropping season. High moisture availability and average to below average maximum temperatures provide more opportunity for sowing temperate crops and pastures. Water availability for production remains strong, with high on-farm dam levels across much of the state and irrigation schemes are at full capacity.

Parts of Western NSW and the western Murray regions previously in the Drought Affected categories have now moved into the Non-Drought category. Consistent follow-up rain is needed to maintain the improved conditions and provide opportunities for longer-term drought recovery.

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 May and July. The ENSO Outlook status is currently at La Niña and the Indian Ocean Dipole (IOD) is neutral, providing the setting for continued rainfall particularly along the NSW East coast. Models indicate that the IOD may become negative in the coming months which tends to bring above average winter rainfall across the state. Sea surface temperatures in the central to eastern tropical Pacific Ocean remain cooler than average. Warmer than average sea surface temperatures have weakened slightly around the Maritime Continent and strengthened to the north-west of Australia.

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. To report local conditions, use DPI Farm Tracker.

Rainfall

The rainfall anomaly data shows the difference between total monthly rainfall and the long-term average monthly rainfall (1961-1990; Figure 2a). Average to above average rainfall has been received across most of NSW in April. Negative rainfall anomalies have been recorded in the North West, Northern Tablelands, North Coast and Hunter Local Land Service (LLS) regions. The highest positive rainfall anomalies were in areas of the Central West and along the south coast.

The higher rainfall totals were recorded in the North Coast LLS region around Coffs Harbour, and the South East region south of Wollongong where rainfall of more than 200mm has been received (Figure 2b). Areas across northern NSW, Riverina and Murray LLS regions have received less than 50mm of rainfall. For the calendar year to date coastal NSW has received between 600mm to above 1200mm of rainfall. Rainfall west of the Great Dividing Range has totalled between 50mm and 400mm (Figure 2c). Year to date rainfall has been moderately above average for central NSW and very much above average for coastal NSW.

Temperature

Eastern NSW experienced near average maximum temperatures for April, whilst western NSW experienced average to above average maximum temperatures (Figure 3a). The average April maximum temperatures ranged from 12°C to 27°C in eastern NSW. Areas west of the Great Dividing Range had maximum temperatures above 24°C, and above 27°C for north western areas of NSW (Figure 3b).

Minimum temperatures were generally slightly above average across most of NSW in April, and more than 2°C above average across parts of southern and western NSW (Figure 3c). The average April minimum temperatures were above 3°C in eastern NSW and above 9°C in the west (Figure 3d). Minimum temperatures in the Tablelands ranged from 6 to 12°C, whilst frost was experienced in the Southern alpine regions where temperatures of 0°C were recorded (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 February to April period. Slightly lower than normal plant greenness remains evident across parts of the Western, the North West and Murray LLS regions. The Greater Sydney LLS region is missing data due to cloud cover and parts of the region are shaded white in this month's map. 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 40% of capacity across eastern areas of NSW and above 80% capacity in regions that have received higher rainfall totals (Figure 5). Areas of western, southern and some coastal regions of NSW have farm dam levels less than 20% of capacity.

Soil Water Index

The Soil Water Index (SWI, Figure 6) indicates the majority of NSW is currently in the average to above average categories. This is a result of the rainfall that has been received over the past several months. Areas of the South East LLS region are in the extremely high category. Parts of western and south-western NSW remain in the below average category.

Plant Growth Index

The Plant Growth Index (PGI, Figure 7) indicates that the majority of NSW is in the average to above average categories at the end of March. Parts of south-western and western NSW reflect a similar pattern with the SWI and are in the below average category. Areas of the South East in the extremely high category also somewhat reflect the SWI.

Rainfall Index

As a result of rainfall received in April the Rainfall Index (RI, Figure 8) indicates all of NSW is in the average category or higher. Most of eastern NSW is currently in the extremely high or above average categories; 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 wetting trend in the Western and Central West LLS regions, and east of the Great Dividing Range along coastal NSW. This a result of the persisting La Niña event and east coast low pressure system delivering high rainfall events to coastal NSW. A strong drying trend is apparent along the Tableland regions. Weaker drying trends can be seen in the northern and southern areas of NSW. There is a weak wetting trend throughout the west of the state. The drying trends are a result of extremely high rainfall recorded in Spring 2021, where recent conditions in these areas have been drier relative to the wet spring period. This weak to strong drying trend does not indicate the emergence of a drought in the regions.

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 30 April 2022. The following regional descriptions are based on data available until the end of April 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 now in the Non-Drought category.

The seasonal NDVI anomaly data (Figure 12) shows that most of the Murray and Riverina regions were experiencing higher than normal plant greenness levels for the February to April period. The impact of the 2019/2020 bush fires is still evident south of Tumut.

The time series charts (Figure 13) show the individual response of the drought indices for Hay, Temora, Finley, and Moulamein. Temora and Finley remain steady with average to high soil water, plant growth and rainfall indices. Continued rainfall and average temperatures have allowed Hay to remain in the Non-Drought category. Although recent rainfall has improved conditions at Moulamein, further rainfall is required to maintain conditions in the region. 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 region excepting the far south western corner is now in the Non-Drought category. Recent rainfall has improved conditions in the south west of the region and drought conditions are weakening. Further rainfall is needed to support long-term drought recovery and maintain Non-Drought conditions across the region. The DPI continues to closely monitor conditions in Western LLS.

The seasonal NDVI anomaly data (Figure 15) shows variability across the Western LLS region. Much of the region is experiencing near normal to high levels of plant greenness for the February to April period. Areas in the far west and south-west continue to have slightly lower than normal plant greenness levels.

The time series charts (Figure 16) show the individual response of the drought indices for Bourke, Ivanhoe, Wentworth, and Broken Hill. Ivanhoe remains in the Non-Drought category with high soil water, plant growth and rainfall indices. Continued rainfall is required at Bourke, Wentworth and Broken Hill to maintain the Non-Drought status and improve the soil water and plant growth indices. 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 North West, Northern Tablelands and North Coast Local Land Service regions continue to experience strong conditions for production given rainfall received over the past year. The Combined Drought Indicator (CDI, Figure 17) shows that the LLS regions are in the Non-Drought category.

The seasonal NDVI anomaly data (Figure 18) indicated near to above-normal greenness across most of the regions for the February to April period. Parts of the North West have average to slightly below average levels of greenness. The dark brown areas showing below average greenness south of Lismore and east, north-east of Grafton are likely be due to flooding impacts over the past few months.

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 April. Productive conditions have generally been maintained due to rainfall received over the past year.

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 February to April period. The white patch in Figure 21 is missing data due to cloud cover.

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. These regions currently remain well placed for productive conditions in the coming months. 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 remains in the Non-Drought CDI category. Productive conditions have generally been maintained due to rainfall received over the past year.

The seasonal NDVI anomaly data (Figure 24) showed near normal to high levels of plant greenness across most of the region for the February to April period. Some areas impacted by the 2019/20 bushfires continue to have lower than average plant greenness levels.

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. These regions currently remain well placed for productive conditions in the coming months. 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 28 April 2022. Rainfall during May to July is likely to be above median for most of 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 inland, central, and southern Australia during the May to July period. Northern, south west and south eastern Australia are likely to be warmer than median. Minimum temperatures for May to July are likely to be above median across Australia.

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

NSW outlook

NSW has a 55% to above 80% chance of receiving above median rainfall between May and July with the lower rainfall forecast east of the Great Dividing Range (Figure 26).

The maximum temperature outlook (Figure 27) indicates a less than 20% to 45% chance of warmer than median temperatures across western, central and inland eastern NSW. There is a 50% to above 75% chance of above median maximum temperatures along parts of eastern NSW.

There is an 80% or greater chance of warmer than median overnight temperatures across NSW (Figure 28). Most of eastern NSW has a 75% to above 80% chance of warmer overnight temperatures.

Global climate drivers

El Niño–Southern Oscillation (ENSO)

The Bureau of Meteorology’s (BoM) El Niño-Southern Oscillation (ENSO) Outlook was released on 26 April 2022. The La Niña has weakened in the tropical Pacific Ocean. However, it may still contribute to weather events in the coming months. Climate models suggest that neutral ENSO conditions will return in late autumn or early winter 2022. La Niña typically increases the chance of tropical cyclones and above median rainfall in NSW during spring and summer, with a weaker influence during autumn.

Southern Oscillation Index

The 30-day Southern Oscillation Index (SOI; Figure 29) for the 30 days ending 26 April was +17.4. The 90-day SOI value was +14.3. 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) remain cooler than average along the equator in the central to eastern tropical Pacific Ocean and the coast of South America. Warmer than average SSTs have weakened slightly around the Maritime Continent and strengthened to the north-west of Australia (Figure 30).

The latest values of the three NINO indices in the tropical Pacific for the week ending 24 April were: NINO3 -0.5°C, NINO3.4 -0.6°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 21 April 2022) shows cool anomalies in the central and eastern equatorial Pacific Ocean have remained similar to those from March (Figure 31). Warm anomalies of up to 4ºC above average from a depth of 100m to 200m currently extend west of the International Date Line.

Indian Ocean (IOD)

The Indian Ocean Dipole (IOD) remains neutral. Of the five international climate models surveyed by the Bureau of Meteorology, four models indicate that the IOD could become negative in the coming month. A negative IOD increases the likelihood of above average winter-spring rainfall across Australia. The latest weekly value of the Indian Ocean Dipole (IOD) index to 24 April 2022 was +0.01 °C.

Southern Ocean (Southern Annular Mode – SAM)

The Southern Annular Mode (SAM) index is positive (as of 30 April) and is expected to return to neutral in early May (Figure 32). A neutral SAM typically has very little influence on the climate in New South Wales.

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. SAM forecasts are highly uncertain beyond 2-3 weeks.

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.

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.