NSW State Seasonal Update - October 2022

Prepared by NSW DPI

NSW overview

October rainfall was well above average for most of NSW. Parts of the state are currently experiencing flooding and there is potential of further flooding with more rain forecast. The NSW DPI Combined Drought Indicator (CDI) shows 100% of NSW in the Non-Drought category at the end of October.

Soil water, plant growth, and rainfall indices have remained high across the state. The on-going wet conditions continue to deliver challenges across all agricultural industries particularly with respect to on-ground field management, preparations for harvest of winter crops and sowing of summer crops, and maintaining animal health and welfare.

Water availability for production remains strong, with high soil moisture, and many on-farm dam levels and irrigation schemes at full capacity.

Seasonal climate forecasts indicate cool and very wet conditions are expected to continue across NSW this Spring and into Summer. The latest Bureau of Meteorology Seasonal Outlook indicates a very high chance of above median rainfall across NSW for the three months between November and January. The ENSO Outlook status is at La Niña. The Indian Ocean Dipole (IOD) is negative, increasing the likelihood of above average spring rainfall across eastern Australia.

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 (1961-1990; Figure 2a). Above average rainfall has been received across most of NSW in October. The highest positive rainfall anomalies were recorded in the Western LLS region, north and south of Ivanhoe, as well as in parts of the South East Local Land Services (LLS) and alpine regions. Some negative rainfall anomalies occurred in the Hunter and Greater Sydney LLS regions between Lithgow, Singleton and Newcastle.

The highest monthly rainfall totals were recorded in the southern alpine regions where rainfall of more than 300mm has been received (Figure 2b). Generally, NSW received between 50 and 200mm during October. For the calendar year to date most of coastal NSW has received between 1000mm to above 2400mm of rainfall. Rainfall west of the Great Dividing Range has totalled between 200mm 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

Below average maximum temperatures were experienced across most of NSW in October (Figure 3a). Average to slightly warmer than average maximum temperatures were recorded in the far north coast around Lismore. The average October maximum temperatures ranged from 6°C in the southern alps to more than 27°C in parts of north western NSW. Most of northern NSW experienced day time temperatures above 21°C, except for parts at higher altitudes. Central and southern NSW experienced average day time temperatures below 24°C (Figure 3b).

October minimum temperatures were above average for western, southern, and north eastern NSW. Central NSW, extending to parts of the Hunter and South East LLS regions, experienced below average overnight temperatures (Figure 3c). The average October minimum temperatures (Figure 3d) ranged between 0°C to 6°C in the southern alps. The far north west of NSW recorded the highest average minimum temperature of above 15°C. Minimum temperatures in the Tablelands ranged from 3 to above 6°C. In October the extent of frost was limited to the alpine and tablelands in south eastern NSW (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 August to October period. Slightly lower than normal plant greenness remains evident across parts of the North West, Central Tablelands, and South East LLS regions, whilst levels of plant greenness continue to noticeably improve in western NSW. Some of the extremely negative NDVI areas (brown patches) are water bodies. White areas shown on the map in the North West, Central Tablelands, and Riverina LLS regions is missing data due to cloud cover.

NSW Farm Dam Survey

The NSW Farm Dam Survey indicates dam levels are generally greater than 60% of capacity across central, eastern, and parts of western 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 significant areas of NSW due to cloud cover.

Soil Water Index

The Soil Water Index (SWI, Figure 6) indicates the majority of NSW is currently in the extremely high category due continued high rainfall over the past several months.

Plant Growth Index

The Plant Growth Index (PGI, Figure 7) indicates that the majority of NSW is in the extremely high category at the end of October due to recent high rainfall and milder Spring temperatures.

Rainfall Index

The Rainfall Index (RI, Figure 8) indicates that at the end of October most of NSW is now in the extremely high category due to the above average rainfall received over the past several 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 throughout most of NSW. Both weak and strong drying trends can be seen in the Hunter, Greater Sydney, and part of the South East LLS regions. The drying trends are a result of extremely high rainfall recorded since late autumn and winter 2022 and the comparatively drier conditions in the last month. 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.

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 October 2022. The following regional descriptions are based on data available until the end of October 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 remain in the Non-Drought category at the end of October.

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 August to October period. Some of the extremely negative NDVI areas (brown patches) represent water. 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. Temora remains steady with high soil water, plant growth and rainfall indices. Above average October rainfall and below average temperatures have helped Hay, Finley, and Moulamein stay in the Non-Drought category and has resulted in an increase in the value of their rainfall, soil water, 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 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. Rainfall throughout the region in October has meant that minor to major flood alerts are in place. However, this rainfall has not been uniform and some parts currently have low farm dam levels. 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 the Western LLS region for the August to October period. Flood affected areas may be represented by lower levels of greenness. Some of the extremely negative NDVI areas (brown patches) may represent water.

The time series charts (Figure 16) show the individual response of the drought indices for Bourke, Ivanhoe, Wentworth, and Broken Hill. Average to high soil water, plant growth, and rainfall indices are represented at all locations, and recent rainfall has resulted in an increase in indices at all locations. Parts of the region with saturated soils and high dam levels continue to face production challenges due to flooding and continued wet and cool conditions during winter. 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 August to October period. Parts of the Northern Tablelands have average to well below average levels of greenness. Heavy rainfall experienced in October due to the combined events of La Niña and a negative Indian Ocean Dipole has resulted in flooding to some regions. Flood affected areas may be represented by lower 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 white area near Gunnedah and Quirindi in the North West is missing data due to cloud cover.

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 October.

The seasonal NDVI anomaly data (Figure 21) shows near normal to high levels of plant greenness across most of the LLS regions for the August to October period. Parts of each region have average to well below average levels of greenness. Heavy rainfall experienced in October due to the combined events of La Niña and a negative Indian Ocean Dipole has resulted in flooding to some regions. Flood affected areas may be represented by lower 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 white areas north of Cowra in the Central Tablelands 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. On-going wet conditions over an already saturated landscape and cooler temperatures continue to provide productivity challenges with respect to infield management, lower pasture growth rates and maintaining animal welfare. 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.

The seasonal NDVI anomaly data (Figure 24) showed near normal to high levels of plant greenness have increased across the region in the August to October period. Generally these are productive conditions however, above average rainfall experienced in September due to the combined events of La Niña and a negative Indian Ocean Dipole has resulted in saturated landscapes and very wet conditions. Flood affected areas may be represented by lower 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 time series charts (Figure 25) show the individual response of the drought indices at Bega, Goulburn and Cooma. The three regions are in the Non-Drought category with high soil water, plant growth and rainfall indices. The on-going cool and wet conditions continue to provide production challenges with respect to saturated soils, lower pasture growth rates and maintaining animal welfare. 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 on 3 November 2022. Rainfall during November to January is likely to be above median for the eastern half 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 southern Queensland, New South Wales, Victoria, South Australia and the south coast of Western Australia during the November to January period. Day time temperatures for Tasmania and northern Australia are likely to be warmer than median. Overnight minimum temperatures for November to January are likely to be warmer than median across south eastern and northern Australia. Cooler overnight minimum temperatures are forecast for southern Queensland, north eastern New South Wales, and parts of Western Australia.

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

NSW outlook

Most of NSW has an above 65% chance of receiving above median rainfall between November and January. South eastern NSW has an above 80% chance of receiving above median rainfall, whilst parts of northern, western and central NSW have a slightly lower forecast of 55 to 70% chance of above average rainfall between November and January (Figure 26).

The maximum temperature outlook indicates a less than 20% chance of warmer than median temperatures across the central and eastern NSW. There is a 35% chance of above median maximum temperatures in the far west, and parts of the south coast and north coast of NSW (Figure 27).

There is a 60% to above 75% chance of warmer than median overnight temperatures across southern and western NSW. Most of central and northern 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 El Niño-Southern Oscillation (ENSO) Outlook was released on 25 October 2022. The ENSO Outlook status is currently at La Niña. Atmospheric and oceanic indicators such as the Southern Oscillation Index, tropical Pacific sea surface temperatures and cloudiness near the Date Line are all representative of an established La Niña. Climate models suggest a return to neutral ENSO conditions in early 2023.

Southern Oscillation Index

The 30-day Southern Oscillation Index (SOI; Figure 29) for the 30 days ending 23 October was +19.0. The 90-day SOI value was +15.7. 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 and eastern tropical Pacific Ocean. Cooler SST extended south along the South American coastline, strengthening since September. Warmer than average SST 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 23 October were: NINO3 -0.7 °C, NINO3.4 -0.7 °C, NINO4 -0.8 °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 20 October 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. Some anomalies west of 160^oE were more than 2.5 degrees warmer than average. A consistent pattern of anomalies has been observed in the equatorial Pacific Ocean over August, September and October.

Indian Ocean (IOD)

The Indian Ocean Dipole (IOD) is currently negative. Five of the six international climate models surveyed by the Bureau of Meteorology indicate that the negative IOD will continue throughout Spring. 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 23 October 2022 was -0.73 °C.

Southern Ocean (Southern Annular Mode – SAM)

The Southern Annular Mode (SAM) index is neutral (as of 04 November) however, it is expected to return to positive values from early to mid-November (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 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.