Prepared by NSW DPI
Despite dry conditions over much of NSW in June, the drought event continued to weaken across large areas of NSW in June 2020. The NSW DPI Combined Drought Indicator (CDI) showed that 86.9% of the state was in one of the three drought categories at the end of June. This is a slight improvement from May, primarily due to the continuation of favourable conditions in parts of central and southern NSW. Rainfall over the next three months is crucial in these areas for recovery to continue. Currently, the official climate outlook and global climate drivers signal an increased chance of rainfall developing in late winter and early spring.
Despite the improvements, the situation is complex and most of the state remains in the Drought Affected category. This currently represents a range of conditions. Consistent rainfall has allowed some central and southern areas to maintain strong potential for drought recovery, while recent dryness in other areas such as the north east has slowed recovery. In some situations, such as western NSW, the Drought Affected category includes areas where little relief has been experienced and full-scale drought response activities continue.
Intense Drought conditions persist in parts of western, south-east and northern NSW. There has been no relief and these regions need effective rainfall to improve conditions.
The latest remote sensing data validates the variability unfolding across the state. Large areas continue to reflect improved plant activity over the last three months, however the analysis also highlights areas, especially in western NSW, where rainfall has been lower or less effective.
Optimism continues for most of the 2020 winter crop, though field reports indicate dry conditions are affecting some crops in the south-west. Winter rainfall remains an important factor for maintaining high yield potentials across the state and to continue building summer crop opportunities later in the year. Substantial rain is still needed to improve water supplies in the state’s irrigation systems.
While weakening drought conditions has provided pasture feed in many regions, the focus is now on the Spring production season. Sustained growth during Spring is important for continued drought recovery during the remainder of 2020. Cold winter conditions have reduced current feed growth in many regions and for the next few months, especially in the tableland districts.
Given the complex and variable situation unfolding across the state, a ‘watch and monitor’ status is still advised. Many regions are still susceptible to a ‘false recovery’, despite the improved conditions. The seasonal climate outlook at the end of July, combined with a reassessment of the drought situation across the state are key factors for judging the potential of longer-term recovery.
The official Seasonal Climate Outlook released by the Bureau of Meteorology (BoM) 2 July 2020 indicates that most of NSW has a near equal to moderate chance of receiving above median rainfall in the July to September period. Despite this, July is forecast to be drier. The main global climate drivers in the Pacific and Indian Oceans continue to show favourable trends, prompting the BoM to issue a La Nina watch status. A La Nina event in the Pacific and the current warming of the central and eastern Indian Ocean are associated with above to well above median rainfall across south east Australia during Spring.
Producers and members of rural communities are encouraged to maintain contact with their local professionals who can facilitate access to appropriate support. If you or someone you know needs support, please visit DroughtHub. Alternatively, you can contact the DPI Rural Resilience Team, Rural Financial Counsellors, or your Local Land Services representatives.
It is important to recognise the CDI provides an aggregated view of the State, 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.
Drought duration is an important component of a drought events impact on farm businesses and communities. The drought duration map (Figure 2) shows the number of months since June 2017 that an area in NSW has been in one of the three CDI drought categories. The map shows that NSW continues to experience long-term drought conditions at 30 June 2020. Despite some Drought Affected areas experiencing the early stages of a transition towards drought recovery, the majority of NSW has experienced drought conditions for longer than two years.
*Note: The accumulated months reported are non-consecutive.
The rainfall anomaly data shows that most of NSW received below average rainfall during June (Figure 3a). The map shows the difference between total monthly rainfall and the long-term average (1961-1990). Anomalies were higher on the South Coast while some parts of the southern slopes, southern tablelands and alpine areas received higher than average rainfall during the month.
June rainfall totals varied across NSW (Figure 3b). The North Coast and parts of the Central Coast, Southern Slopes, Southern Tablelands and alpine areas received totals between 50-100mm. Isolated areas received 100-200mm in these districts. Rainfall totals were lower further west. Large areas in the north-west received less than 10mm during the month.
Rainfall accumulation for 2020 has been near or above average for most of NSW, however areas in the far west and south east of the state continue to experience dry conditions and have received well below average rainfall during 2020. Large areas east of the Great Dividing Range have accumulated totals of above 600mm (Figure 3c). Higher totals of more than 1,000mm have been received on the North and Central Coast. Conditions in the far west have been dry with some areas receiving less than 50mm for the year. Despite large areas of below average rainfall in May and June, rainfall accumulation in 2020 has positioned some regions well for recovery if follow-up rain is received in coming months.
Daytime temperatures in June were 0-2°C above average across most of NSW (Figure 4a). The average daytime temperatures recorded in June (Figure 4b) were 18-21°C across most of the north western and northern coastal regions of the state. The south west, Central West and northern slopes received temperatures between 15-18°C, while most of the tablelands areas and southern slopes were cooler ranging between 12-15°C. Areas at higher altitudes in the tablelands and alpine areas experienced daytime temperatures between 3-12°C.
Overnight temperatures were 0-3°C below average across most of western NSW in June (Figure 4c). In contrast, overnight temperatures in most of eastern NSW were 0-1°C above average. Most of the state experienced overnight temperatures between 3-6°C (figure 4d). Temperatures were warmer in most coastal regions ranging between 6-12°C, while the regions at higher altitude in the tablelands received temperatures between 0-3°C. Tableland areas further south and in the alpine regions received overnight temperatures ranging between -3-0°C.
The frost days map (Figure 4e), shows the number of days that overnight temperatures did not exceed 0°C across the state in June. The areas receiving frost conditions increased from May as we move through winter.
The seasonal Normalised Difference Vegetation Index (NDVI, Figure 5) indicates that drought conditions have weakened substantially in many areas of the state during the Autumn and early winter period. Plant greenness levels are closer to normal values across much of the state and are above normal in many central, southern and eastern areas.
The analysis also highlights regions that are still experiencing below normal levels of greenness. Plant greenness is below normal in many western areas, as well parts of the North West and South East areas of the State. Severe plant greenness deficiencies are still evident in much of the bushfire affected areas of the Central Tablelands, South East and Alpine areas of the state.
A number of technical factors need to be considered when considering the new analysis:
The latest data from the NSW Farm Dam Survey indicates that dam levels in much of central NSW have been improving since April and are generally above 60% of capacity. Parts of the Riverina and Murray Local Land Services (LLS) regions have also improved since the last update, though there is still a high variability in these regions. Other areas of the state show similar or declining dam levels since April including parts of the north-west, Northern Tablelands, western and coastal regions. Severe deficiencies remain across large parts of the Western, Riverina, Murray and South East LLS regions.
The short-term response of soil water and accumulated pasture growth is shown in Figure 7a and Figure 7b. The average soil water recharge over the past 30 days indicates that much of the coast north of Batemans Bay and parts of central and southern NSW are showing a response to recent rainfall. A similar trend is indicated for accumulated pasture growth over the last 30 days in these regions. Elsewhere, dry conditions in May and June have affected soil water accumulation and potential plant growth rates over the last 30 days.
The Soil Water Index (SWI, Figure 8) remains below average across most of NSW. The index shown some improvements in parts of the Central West and southern areas of the North West since the May 2020 State Seasonal Update. Rainfall accumulation during 2020 has slowly improved the soil water index in these areas compared to the same time in 2019.
The Plant Growth Index (PGI, Figure 9) remains below average to extremely low across most of NSW at the end of May. There has been a retraction of the average PGI in western NSW since the last State Seasonal Update. Any improvements to the index remain slow with little change in the spatial distribution of the data since the end of May.
Rainfall accumulation during 2020 has improved the Rainfall Index (RI, Figure 10) across large areas of NSW. The majority of NSW continues to be average to below average and remains stable since the May State Seasonal Update.
The Drought Direction Index (DDI, Figure 11) tracks the trend of rainfall accumulation relative to long-term data. The DDI shows that most of the state is displaying a weak to strong drying trend due to insufficient rainfall in May and June relative to longer-term rainfall accumulation over the last five months.
Changes in the individual drought indicators may have occurred since this update was released. For the most current information, please visit DroughtHub.
Figure 12 displays the CDI status for each individual Local Land Services regions to 30 June 2020. The regional descriptions are based on data available until the end of May 2020.
Rainfall in June has maintained conditions across the much of Murray and Riverina Local Land Services (LLS) regions. The Combined Drought Indicator (CDI) shows most of the region is still in the Drought Affected CDI category (Figure 13), though there are areas that are showing the early signs of drought recovery. On-ground reports indicate that some areas further west still need substantial rain to see improvements in conditions and to maintain winter crop potentials. Generally, the region remains well positioned for a transition towards recovery, though consistent rainfall will be needed in the lead up to and throughout Spring.
The seasonal NDVI anomaly data (Figure 14) has shown similar plant greenness anomalies since the June State Seasonal Update. Much of the region is experiencing normal to higher than normal plant greenness for the April to June period. The impact of the recent bush fires is still evident south of Tumut.
The time series charts (Figure 15) show the individual response of the drought indices for Hay, Finley, Temora and Moulamein. The Hay, Finley and Temora charts show that conditions continue to transition towards drought recovery and are in a good position if rainfall continues to support recent improvements. The Moulamein charts show how conditions have plateaued since May. This is an example of a how some areas, particularly in the west, need further rain to sustain recent improvements.
Autumn rainfall improved conditions in many parts of the Western Local Land Services region (LLS). However due to a dry June, there has been little if any improvement since the May State Seasonal Update. Much of the region continues to manage long-term drought conditions, with on-ground reports confirming that the rainfall has been extremely variable and that the response to rainfall has been mixed.
While the drought weakened in some parts of the Western LLS region over recent months, the majority of the region has not had any relief. A series of effective rainfall events is still needed to initiate a substantive change in conditions and initiate any transition towards drought recovery.
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 is then ranked against all other 12-month periods. 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. As of 30 June 2020, the CDI shows that most of the region is in one of the three CDI drought categories (Figure 16). Ongoing drought conditions have been experienced across Western LLS region for over 2 years (Figure 2).
The seasonal NDVI anomaly data (Figure 17) shows the high degree of variability in plant greenness levels across the region compared to the long-term expectations for the April to June period. The data highlights that rainfall totals have been low or ineffective in many parts of the region over recent months (brown areas on the map), while in other areas the rainfall has provided a positive plant growth response.
Given the inherent nature of the environment in western NSW, it is likely that drought recovery will remain variable and take time. There has been a long-term absence of consistent rainfall across the region. A consistent rainfall pattern is needed to support a long-term sustained recovery to drought conditions.
The time series charts (Figure 18) show the individual response of the drought indices for Bourke, Ivanhoe, and Wentworth. Bourke and Ivanhoe have experienced a recent improvement compared to Wentworth, however follow-up rainfall is needed to continue these improvements. There is an example of a false early-stage recovery at Ivanhoe in April and May 2019. This highlights the importance of follow-up rainfall for sustaining the potential of longer-term drought recovery. To access a time series for your Parish visit the Combined Drought Indicator website.
Despite rain during 2020, the majority of the North West, Northern Tablelands and North Coast Local Land Services (LLS) regions continue to be in one of the three Combined Drought Indicator (CDI) drought categories (Figure 19). Most of the regions are in the Drought Affected category and relatively dry conditions in June have slowed the transition towards recovery in some districts. Follow up rainfall will be needed in the lead up to and throughout Spring to sustain improvements in the long-term.
Parts of the Northern Tablelands and North Coast LLS regions remain in Drought and Intense Drought at the end of June. These areas have lower drought recovery potential and need consistent follow-up rainfall. Irrigation storages generally remain well below capacity and substantial rainfall is needed to recharge these systems.
While the CDI shows varying levels of drought intensity across these regions, the remote sensing satellite data shows encouraging levels of plant greenness for the April to June period. The seasonal NDVI anomaly data (Figure 20) indicates positive anomalies across much of the region for the period. The data indicates that rainfall received earlier in the year was extremely effective for improving pasture and on-ground conditions during autumn and early winter. Despite this, the rain has not been substantial enough to change the longer-term deficit in conditions tracked by the CDI. The drought indicators examine the last twelve months relative to a long-term comparison. To alleviate these long-term deficits further rain is needed during the remainder of winter to recharge soil water levels and optimise growth potential during Spring.
The time series charts (Figure 21) show the individual response of the drought indices for Moree, Walgett and Tenterfield. Despite rain in 2020, the improvement to the indices have slowed or plateaued in recent months. The time series chart for Lismore illustrates an example of a region that transitioned out of drought into the Recovery CDI category and then quickly reverted back to the Drought Affected category. This shows the importance of follow-up rainfall for sustaining improvements to conditions despite the large rain totals received in the region earlier in the year.
Rain over recent months has weakened drought conditions substantially in many areas of the Central Tablelands, Central West, Hunter and Greater Sydney Local Land Services (LLS) regions. While most of the regions are still categorised in one of the three Combined Drought Indicator (CDI) drought categories (Figure 22), many of the Drought Affected areas are experiencing a transition towards a longer-term drought recovery. Most of these regions remain well placed for recovery, especially in the Central West where effective rainfall has improved conditions since the start of the year.
The seasonal NDVI anomaly data (Figure 23) indicates a general positive response to rainfall during autumn and in June. The remote sensing satellite data currently shows above expected levels of plant greenness across large areas of these LLS. The bushfire impact remains evident in parts of the tablelands.
The time series charts (Figure 24) show the individual response of the drought indices for Cowra, Condobolin and Singleton. Drought conditions have impacted the region for an extended period, where the soil moisture and plant growth indices struggled to surpass the lowest 10th percentile of the long-term data. The rain in recent months has improved the indicators, where a positive but slow transition towards drought recovery continues. In all cases, further rain is needed to sustain a longer-term drought recovery.
Conditions in northern areas of the South East Local Land Services (LLS) region continue to show improvements and early signs of drought recovery since the start of the year. Many areas in the north of the region are well placed for a longer-term drought recovery if favourable conditions are received during the remainder of winter and into spring.
In contrast, southern areas have remained dry and had little relief. The southern areas remain in the Intense Drought Combined Drought Indicator (CDI) category during June (Figure 25). These areas are now in a period of slow plant growth rates with cold winter conditions. Southern areas still require consistent winter rainfall to replenish long-term soil moisture deficits for potential improvements in Spring.
The seasonal NDVI anomaly data (Figure 26) shows a higher than expected level of plant greenness in much of the north. Rainfall totals have been higher and more effective in these areas. Plant greenness levels remain below expected levels in the south and the areas impacted by bushfires continue to stand out.
The time series charts (Figure 27) show the individual response of the drought indices at Bega, Goulburn and Cooma. They show large variations between locations. Goulburn has shown the greatest improvement of the indices since April. All locations show the importance of follow-up rain for sustaining improvements to the indices longer-term.
The latest official national outlook was released by the Bureau of Meteorology (BoM) on 23 June 2020. The outlook indicates that July rainfall is likely to be below average for large parts of Australia. However, a wetter than average month is likely for parts of the tropical north and western Tasmania. The outlook for August to October indicates higher chances of above median rainfall for three-month period across most of the eastern two thirds of Australia. Chances of exceeding median rainfall are roughly equal for much of WA and western Tasmania.
The tropical Pacific Ocean is expected to approach La Niña levels over the coming months and warmer than average waters are also likely in much of the central and eastern Indian Ocean. The situation unfolding in both the Pacific and Indian Oceans is influencing the outlook for higher than median rainfall in the August to October period. In the shorter-term, higher than average atmospheric pressure is likely to dominate much of Australia from early July and is causing a forecast of drier conditions.
Both daytime and overnight temperatures are likely to be warmer than average across Australia during July to September.
NSW currently has a near equal to moderate chance of receiving above median rainfall in the July to September period. Despite this, July is more likely to be drier across the state. Parts of western, north- western and the central and southern tablelands have higher probability of receiving above median rainfall during the period (Figure 28).
The BoM temperature outlook for July to September (Figure 29 & 30) indicates both daytime and overnight temperatures have an increased likelihood of being above median across NSW.
The Bureau of Meteorology’s (BoM) El Niño–Southern Oscillation (ENSO) Outlook was released on 23 June 2020. The El Niño–Southern Oscillation (ENSO) indicators remained neutral during the month, however the recent cooling in the tropical Pacific Ocean has continued. The majority of models indicate this cooling to continue with temperatures forecast to be near La Niña thresholds by early spring. Consequently, the Bureau's ENSO Outlook has shifted to La Niña WATCH.
La Niña WATCH means the chance of La Niña forming in 2020 is around 50% - roughly double the average likelihood. Three models indicate a La Niña could form by late winter, with two other models suggesting thresholds could be reached during early spring. La Niña events typically bring above average spring rainfall in northern, central, and eastern Australia.
Note that recent ENSO predictions made during the Australian autumn tend to have lower skill. Models have a greater sensitivity to volatile short-term weather patterns during this period. Forecast skill now improves as we approach mid-winter.
The 30-day Southern Oscillation Index (SOI) for the period ending 21 June was −9.7. The 90-day value was −3.7. While the 30-day SOI has dropped over the past fortnight, mostly due to higher pressure at Darwin, the longer-term 90-day SOI is still well within the ENSO neutral range.
Sustained negative values of the SOI below −7 typically indicate El Niño while sustained positive values above +7 typically indicate La Niña. Values between +7 and −7 generally indicate neutral conditions.
Sea surface temperature (SST) patterns across the tropical Pacific Ocean for the week ending 21 June remain largely unchanged compared to that of two weeks ago. Cooler than average SSTs have increased slightly in the eastern half of the equatorial Pacific Ocean, while warmer than average SSTs in the far western Pacific have increased in area but weakened in intensity. Much of the central tropical Pacific SSTs are close to average for this time of the year.
SSTs remain slightly warmer than average around large parts of Australia, however they are cooler away from the coast in the Great Australian Bight.
The latest values of the three key NINO indices in the tropical Pacific for the week ending 21 June were: NINO3 −0.6 °C, NINO3.4 −0.2 °C and NINO4 +0.3 °C. NINO3.4 and NINO3 have cooled over the past fortnight while NINO4 has not changed.
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.
The four-month sequence of equatorial Pacific sub-surface temperature anomalies (to 18 June) shows cooler than average waters extend in a band across the majority of the equatorial Pacific. These cooler temperatures exist at a depth of around 100-200m in the western to central equatorial Pacific and rise to the top 50m at the eastern edge of the equatorial Pacific.
In the western equatorial Pacific, very weak warm anomalies persist and have spread slightly compared to May.
Since January, the pattern of cooler anomalies at depth has persisted. This is supporting conditions favourable for potential La Niña development.
The Indian Ocean (IOD) status is currently neutral. Despite recent cooling in the eastern Indian Ocean, three of six models continue to indicate the possibility of a negative IOD developing during winter or early spring. Most models show a broad spread of likely scenarios between the neutral and negative IOD range. A negative IOD typically brings above average winter–spring rainfall to southern Australia.
The skill of recent IOD forecasts issued in autumn is typically low. As we progress into winter, skill in these model outlooks improves dramatically.
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 offers shorter-term influence on actual weather conditions.
The Southern Annular Mode (SAM) is currently positive and is forecast to remain positive during early July (as at 20 June 2020, Figure 34).
During winter, a positive SAM typically means less rainfall for southwest Western Australia, southern Victoria, and Tasmania.
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:
The way in which the indicators are combined to form the CDI is described in Table 1 below.
Table 1: The way in which the indicators are combined to form the CDI.
Description - typical field conditions
All three indicators (rainfall, soil water, plant growth) are below the 5th percentile
Ground cover is very low, soil moisture stores are exhausted and rainfall has been minimal over the past 6-12 months.
At least one indicator is below the 5th percentile
Conditions may be very dry, or agronomic production is tight (low soil moisture or plant growth). It is possible to be in Drought when there has been some modest growth, or a few falls of rain.
Drought Affected (intensifying)
At least one indicator is below the 30th percentile and the rainfall trend is negative over the past 90 days.
Conditions are deteriorating; production is beginning to get tighter. Ground cover may be modest, but growth is moderate to low for the time of year. When indicators are close to the Drought threshold drought conditions are severe.
Drought Affected (weakening)
At least one indicator is below the 30th percentile and the rainfall trend is positive over the past 90 days.
Production conditions are getting tighter, but there have been some falls of rain over the past month. It is rare to enter the Recovering phase from the Non-Drought category; Usually there is a quick (1-2 week) transition into Drought Affected or Drought. When indicators are close to the Drought threshold drought conditions are severe.
All indicators are below the 50th percentile but above the 30th percentile
Production is occurring but would be considered ‘below average’. Full production recovery may not have occurred if this area has experienced drought conditions over the past six months.
At least one indicator is above the 50th percentile.
Production is not limited by climatic conditions.
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 (2020), Panorama Avenue, Bathurst 2795 and data which is © Commonwealth of Australia 2020, 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.
© State of New South Wales through the Department of Regional New South Wales, 2020. You may copy, distribute and otherwise freely deal with this publication for any purpose, provided that you attribute the NSW Department of Primary Industries as the owner.
Disclaimer: The information contained in this publication is based on knowledge and understanding at the time of writing (July 2020). However, because of advances in knowledge, users are reminded of the need to ensure that information upon which they rely is up to date and to check currency of the information with the appropriate officer of the Department of Primary Industries or the user’s independent adviser.
Published by the NSW Department of Primary Industries. ISSN 2202-1795 (Online). Volume 8 Issue 6.