NSW State Seasonal Update - February 2023

Prepared by NSW DPI

NSW overview

The NSW DPI Combined Drought Indicator (CDI) shows 100% of NSW in the Non-Drought category at the end of February. Despite drier conditions over New South Wales in January and February the production outlook for autumn remains strong.

Intermittent summer rainfall has maintained pasture and supported dryland summer cropping in some areas. Drier conditions have enabled summer weed management, preparation for early sowing of winter crops and pastures, and silage production in areas impacted by recent flooding. Pasture availability remains high in many regions although the nutritional value of pasture for livestock has declined over recent months.

Average to below average rainfall from December through to February has reduced dam levels in some areas particularly in the north and northwest of the state. Subsoil moisture levels remain high, although a timely autumn break will be needed to establish winter crops. Water availability for production remains positive, with many irrigation storages at near full capacity.

Seasonal climate forecasts indicate warmer than average days for most of NSW for the March to May period. Overnight temperatures are likely to be average to warmer than average for eastern NSW during this period. Rainfall is likely to be below average for most of NSW between March to May reflecting various climate drivers including a La Niña close to its end. The Indian Ocean Dipole (IOD) is neutral, with a low likelihood of influencing Australian climate in the next few months.

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). Below average rainfall has been received across most of NSW in February. The highest negative rainfall anomalies were recorded in the North Coast LLS region. The highest positive rainfall anomalies were recorded in the far north coast, west of Dubbo in the Central West, and south of Singleton in the Hunter LLS region.

The highest monthly rainfall totals in February were recorded along parts of coastal NSW where rainfall of more than 100mm was received (Figure 2b). The western half of NSW received less than 5mm of rainfall in February. For the calendar year to date most of coastal NSW has received between 100mm to above 300mm of rainfall. Rainfall west of the Great Dividing Range has totalled between 10mm and 100mm (Figure 2c). Year to date rainfall has been average to below average for most of NSW and slightly above average for the southeast of the Murray LLS region.

Temperature

Near average maximum temperatures were experienced across most of NSW in February. Maximum temperatures were 1 to 2 degrees below average in southern NSW and 1 to 2 degrees above average across northern NSW, including parts of the North West and Hunter LLS regions (Figure 3a). In February the average maximum temperatures ranged from 15°C in the southern alps to above 36°C in northwestern NSW. Most of NSW experienced day time temperatures above 27°C. Temperatures were generally cooler in the east: parts of the Tablelands and southeast NSW experienced average day time temperatures below 24°C (Figure 3b).

Minimum overnight temperatures were below average for most of NSW in February. Temperatures were 1 to more than 2 degrees below average across parts of central NSW and slightly below average in the north west, and along the central and south coasts (Figure 3c). The average February minimum temperatures (Figure 3d) ranged between 3°C to 12°C in the Alpine and Tablelands. The far northwest of NSW recorded the highest average minimum temperatures of above 21°C. A small number of frost days were recorded for February in the alpine region (Figure 3e).

Normalised Difference Vegetation Index (NDVI) Anomaly

The seasonal Normalised Difference Vegetation Index (NDVI, Figure 4) indicates that plant greenness levels are near normal to slightly below normal for central and eastern areas of NSW, and normal to well above normal for western areas of NSW for the December to February period. 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 central and eastern NSW (Figure 5). Areas west of the Great Dividing Range and parts of northern and coastal NSW maintain farm dam levels at less than 40% of capacity. Data is unavailable for some areas of NSW due to cloud cover.

Soil Water Index

The Soil Water Index (SWI, Figure 6) shows that most of NSW is currently in the extremely high category. Soil water conditions have moved into the above average category in parts of eastern and northern NSW due to the low and variable rainfall received in January and February.

Plant Growth Index

The Plant Growth Index (PGI, Figure 7) shows that most of NSW is in the extremely high category at the end of February due to the high spring rainfall. Some areas of eastern NSW show an average to above average PGI due to the variable January and February rainfall and warm summer temperatures.

Rainfall Index

The Rainfall Index (RI, Figure 8) for 2023 shows that at the end of February most of NSW is in the extremely high category. Drier December conditions and variable rainfall in January and February have led to parts of northern and eastern NSW moving back into average to above average RI values.

Drought Direction Index

The Drought Direction Index (DDI, Figure 9) tracks the 150-day trend of daily rainfall totals. The DDI shows a strong drying trend throughout most of NSW. Both wetting and drying trends can be seen in parts of eastern NSW. The wetting trends are a result of the higher rainfall amounts received recently from summer storms in February. The drying trends are a result of extremely high rainfall recorded in 2022 and the comparatively drier conditions in the few last 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 previous very wet conditions.

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 28 February 2023. The following regional descriptions are based on data available until the end of February 2023.

Murray and Riverina regions

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

The seasonal NDVI anomaly data (Figure 12) shows that parts of the Murray and Riverina regions were experiencing higher than normal plant greenness levels for the December to February period. Some of the extremely negative NDVI areas (brown patches) represent water.

The Drought History charts (Figure 13) show the individual response of the drought indicators for Hay, Temora, Finley, and Moulamein. The indicators are high at all locations and suggest a strong outlook to the start of autumn. 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

The Combined Drought Indicator (CDI, Figure 14) shows that the Western LLS region is currently in the Non-Drought category. Minor flood warnings remain in place for the Darling River.

February rainfall was below average for the Western region and some parts have low farm dam levels. Other regions are experiencing high to very high farm dam levels due to flooding in 2022. The DPI continues to closely monitor conditions in Western LLS.

The seasonal NDVI anomaly data (Figure 15) shows normal to very high levels of plant greenness across most of the Western LLS region for the December to February period. Some of the extremely negative NDVI areas (brown patches) represent water.

The Drought History charts (Figure 16) show the individual response of the drought indicators for Bourke, Ivanhoe, Wentworth, and Broken Hill. The Rainfall indicator has declined at Bourke whilst all indicators remain high at Ivanhoe, Wentworth, and 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

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

The seasonal NDVI anomaly data (Figure 18) indicates normal levels of greenness across most of the regions for the December to February period. Parts of the Northern Tablelands and North West LLS regions have average to below average levels of greenness. Some of the extremely negative NDVI areas (brown patches) represent water. The NSW DPI continues to closely monitor conditions in these regions.

The Drought History charts (Figure 19) show the individual response of the drought indicators for Tenterfield, Moree, Walgett, and Lismore. The Plant Growth indicator has declined at Tenterfield and Lismore likely due to below average rainfall received in January and February. These regions should continue monitor conditions closely. 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

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 February. On February 9^th the Central West, Central Tablelands, Hunter, and Greater Sydney LLS regions experienced intense storms that brought flash flooding, heavy rain and hail.

The seasonal NDVI anomaly data (Figure 21) shows near normal to high levels of plant greenness across most of the LLS regions for the December to February period. Parts of the Central West have average to well above average levels of greenness as they begin to recover from inundation and flooding in November. Some of the extremely negative NDVI areas (brown patches) represent water. The NSW DPI continues to closely monitor conditions in these regions.

The Drought History charts (Figure 22) show the individual response of the drought indicators for Cowra, Condobolin and Singleton. The CDI indicators remain high at all locations and suggest a strong outlook to the start of autumn. 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

The Combined Drought Indicator (CDI, Figure 23) shows that the South East Local Land Services region is in the Non-Drought CDI category. On February 9^th severe storms brought flash flooding and heavy rain to the Illawarra and Shoalhaven areas of the South East LLS region.

The seasonal NDVI anomaly data (Figure 24) shows near normal to high levels of plant greenness. Some of the extremely negative NDVI areas (brown patches) represent water. The NSW DPI continues to closely monitor conditions in these regions.

The Drought History charts (Figure 25) show the individual response of the drought indicators at Bega, Cooma and Goulburn. Although there is a decline in the Rainfall indicator at Cooma, indicators remain relatively high. 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.

Official national outlook

The official national outlook was released by The Bureau of Meteorology on 2 March 2023. The rainfall outlook for March to May shows that parts of South Australia, the Northern Territory, areas of eastern and northern Western Australia, northern and western NSW, and most of Queensland have a 60% to 80% chance of below median rainfall. Central and eastern Victoria and most of Tasmania have close to equal chances of above or below median rainfall.  Forecast accuracy at this time of year has generally been moderate to high for eastern and northern Australia.

Maximum temperatures from March to May are likely to be warmer than average for most of Australia, except the New South Wales central coast, and south eastern Victoria which have an equal chance of above or below average maximum temperatures. Above median minimum temperatures are very likely for most of Australia for the 3-month period between March to May. Parts of central Australia, central and eastern South Australia and the Kimberley have a 60% to 70% chance of below median minimum temperatures.

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

NSW outlook

There is a 60% to greater than 80% chance of below median rainfall west of the Great Dividing Range between March and May. Parts of south-east NSW, and the east coast and ranges have a near equal chance to more than 60% chance of receiving above median rainfall over the 3-month period (Figure 26).

The maximum temperature outlook indicates a more than 65% chance of exceeding median daytime temperatures across most of NSW. The chance of warmer than median daytime temperatures increases in the north where there is a greater than 75% chance of above median maximum temperatures in parts of Western, the North West, the Northern Tablelands, and North Coast LLS regions (Figure 27). There is a below average chance of exceeding median temperatures in the Hunter region.

There is a 45% to above 80% chance of warmer than median overnight temperatures in eastern NSW during the March to May period (Figure 28). West of the Great Dividing Range, there is a near equal to less than 35% chance of above median overnight temperatures.

Global climate drivers

El Niño–Southern Oscillation (ENSO)

The Bureau of Meteorology’s El Niño-Southern Oscillation (ENSO) Outlook was released on 28 February 2023. The ENSO Outlook status is currently at La Niña. Sea Surface Temperatures (SSTs) have returned to ENSO-neutral conditions, the weakening of atmospheric ENSO indicators towards neutral values suggest the La Niña is near its end. Six of the seven climate models suggest SSTs will remain at neutral ENSO conditions during autumn.

Southern Oscillation Index

The 30-day Southern Oscillation Index (SOI; Figure 29) for the 30 days ending 26 February was +11.6. The 90-day SOI value was +14.6. 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 central tropical Pacific Ocean. Weak warm anomalies were observed around the Maritime Continent to the north of Australia. Stronger warm anomalies continue to the south of Australia particularly around Tasmania and New Zealand (Figure 30).

The latest values of the three NINO indices in the tropical Pacific for the week ending 26 February were: NINO3 +0.2 °C, NINO3.4 -0.2 °C, NINO4 -0.3 °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 23 February 2023) shows weak cool anomalies to 150m depth in the central to eastern equatorial Pacific Ocean (Figure 31). Warm anomalies of more than 3^oC above average, persist west of 160^oW from 50m to 300m depth.

Indian Ocean (IOD)

The Indian Ocean Dipole (IOD) is currently neutral. Most of the five international climate models surveyed by the Bureau of Meteorology indicate that a neutral IOD will continue throughout autumn. Whilst the monsoon trough is in the southern hemisphere from December to April, the IOD has little influence on Australia’s climate. The latest weekly value of the Indian Ocean Dipole (IOD) index to 26 February 2023 was +0.16 °C.

Southern Ocean (Southern Annular Mode – SAM)

The Southern Annular Mode (SAM) index is neutral (as of 01 March) and is expected to remain neutral during March (Figure 32). A neutral SAM has little influence on Australia’s rainfall and temperature.

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 1-3 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 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 (2022), Panorama Avenue, Bathurst 2795 and data which is © Commonwealth of Australia 2022, 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.