Prepared by NSW DPI Climate Branch
Widespread drought conditions continued to affect New South Wales (NSW) during September 2019. Prolonged drought conditions and an unfavourable three month rainfall outlook continue to provide challenging hydrological and agronomic forward scenarios. The current circumstances indicate that the management of the current drought event will likely be required into 2020. The NSW DPI Combined Drought Indicator (CDI) shows that 97.2% of the state remains in one of the three drought categories at the end of September, with the accumulated drought duration now exceeding 18-24 months for large areas of the state since mid-2017.
September conditions were dry for the majority of NSW. Parts of the southeast and coastal regions of the state were exceptions, where timely rainfall will support spring pasture production and potentially improve dam levels in some areas. Adequate follow up rainfall remains critical in these Drought Affected areas to initiate confidence of longer term production recovery. Despite being beneficial, this rainfall was isolated with many producers in these regions receiving lower totals.
Elsewhere, low September rainfall caused the intensification of drought conditions. As reported over the past few months, more intense drought conditions persist in parts of the Central West, the North and to North-West of NSW. The crop and pasture opportunities existing in parts of southwest NSW has largely declined due to the extent of late winter and early spring dryness. These potential losses may also be compounded due to the occurrence of recent frost events. The poor crop outlook and feed availability occurring in other parts of the state continued, with the intensity of the drought event increasing across northern, the far west and Central West areas of NSW. The majority of these areas received less than 20% of the September monthly rainfall average.
The Bureau of Meteorology (BoM) Climate Outlook released on 4 October 2019, indicates a low likelihood of the drought conditions breaking during the remainder of Spring. The outlook indicates less than a 35% chance of receiving median rainfall across NSW for the next three months. The outlook continues to be driven by a strong positive Indian Ocean Dipole (IOD) event which is expected to peak in October, prior to its influence decreasing when the monsoon trough becomes active towards the end of the year. A positive IOD event is associated with dry conditions for central and southeast Australia and is currently the dominant climate influence, with the El Niño forecast remaining neutral for the remainder of 2019.
The failed 2019 winter recharge of soil and hydrological systems, combined with the poor start to spring continues to impact feed and water availability, while low summer crop potential persists for much of the state. Given that the rainfall outlook is poor relative to requirements, it is expected that widespread pressure will continue for the foreseeable future while productive capacities remain limited and drought management continues.
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 widely recognised as an important component of drought impact on farm businesses and communities. The drought duration map (Figure 2) shows the number of months since June in 2017 that an area in NSW has been in any one of three CDI drought categories; Drought Affected, Drought or Intense Drought. The drought duration map indicates that at 30 September 2019 large parts of NSW have experienced long-term drought conditions for greater than 18 months or more since mid-2017.
*Note: The accumulated months reported in time of drought are non-consecutive.
The majority of NSW received well below average rainfall throughout September. Large areas of the state in northern and western regions received small September totals of 0-10mm (Figure 3), which was less than 20% of the September average. Higher rainfall totals of 50-100mm occurred in the Sydney area and parts of the Central Tablelands, southeast and central coast regions of NSW, however the higher totals had variable distribution with the far south and north coast area in these regions receiving lower totals. Rainfall typically declined in western areas of the state, including most of the southern cropping region where totals of 10-25mm were received for the month.
September daytime temperatures (Figure 4) ranged between 24-30°C across northern NSW including the north coast, with higher elevations in the north ranging between 12-18°C. In central and southwestern NSW, daytime temperatures ranged from 21-24°C, with higher elevations ranging between 15-21°C. Southern slopes and coastal regions received daytime temperatures ranging between 18-21°C, with higher elevations ranging between 9-15°C. The majority of the state experienced warmer than average daytime temperatures of 1-3°C during September. Parts of the Central West and central northern areas of the state, including the Northern Tablelands, received above average daytime temperatures that were higher 3-5°C than the September average.
Overnight temperatures (Figure 5) in large parts of north-western and coastal NSW ranged between 6-12°C. The majority of the slopes regions across the state, as well as parts of southern NSW experienced overnight temperatures ranging between 3-6°C. Areas at higher altitudes received average overnight temperatures between -3 to 3°C. There were large areas of NSW receiving lower than average overnight temperatures throughout the month, including parts of southern NSW, where there have been recent reports of frost and potential damage to crops in the region. The number of days during September when overnight temperatures were below 0°C across the state is shown in Figure 5a.
The Normalised Difference Vegetation Index (NDVI) anomaly (Figure 6) shows that plant greenness levels continue to remain well below the long term levels expected during September across most of NSW. The NDVI is an index that provides a measure of vegetation density and condition. The NDVI anomaly is the deviation of the current NDVI from the long-term average for this time of year.
Dry September conditions have not made any notable improvements to farm dam levels across the majority of NSW. Figure 7 shows that surface water availability remains at critical levels across large areas of the state as temperatures begin to increase during Spring. Any improvements resulting from the higher rainfall totals in parts of southeast and coastal areas of NSW will be reflected in next month’s report given that much of the rainfall received in these areas occurred after the date the data was collected.
The Soil Water Index (Figure 8, SWI) remains below average to extremely low across the majority of NSW. The Sydney area, a small area to the east of Albury in the Murray Local Lands Services (LLS) region, and parts of central and northern areas of the Western LLS region are currently in the average classification. Apart from the Sydney region, rainfall received in September was not sufficient to improve the soil water status, and it is expected that increasing temperatures throughout Spring will diminish soil moisture stores quickly unless consistent above average rainfall is received.
There was little improvement to the Plant Growth Indicator (Figure 9, PGI) during September, including areas that did receive higher totals for the month This reflects the continued dryness being experienced across NSW, The majority of NSW is experiencing below average to extremely low plant growth relative to the long term data.
There were few improvements to the Rainfall Index (Figure 10, RI) during September, including the areas that received higher rainfall totals. This highlights the continuation of dry conditions being experienced across NSW.
The majority of NSW experienced a drying trend during September as indicated by the Drought Direction Index (Figure 9, DDI). This provides another indication for the scale of the dry conditions experienced throughout the month adding to a very dry winter and early spring rainfall period for 2019.
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 region to 30 September 2019.
The Murray and Riverina Local Land Services (LLS) regions continue to experience widespread drought conditions. The Combined Drought Indicator (CDI, Figure 13) shows that the majority of this region is classified as being in the Drought or Drought Affected categories. September rainfall was insufficient to prevent crop yield decline and decreasing feed potential across large parts of the region. Recent reports of frost occurrences have also placed pressure on crop yield potentials. Higher September rainfall totals were received in the eastern and alpine areas of the Murray LLS regions, where signs of drought recovery continue due to higher rainfall totals accumulating during Winter.
The monthly NDVI anomaly data (Figure 14) indicates that the region continues to be experiencing below normal levels of greenness. Below average rainfall during Winter and early Spring has driven poor agronomic activity over the past few months. Areas in the west of the region appear to be slightly better than the east relative to long term expectations.
The time series charts (Figure 15) shows the individual response of the drought indices for Hay, Finley and Temora. The charts show that there have been some beneficial periods of rainfall since May, however conditions have remained marginal for building longer term confidence of sustained drought recovery. So far in Spring, there has been little improvement to conditions and reflects the diminishing potential of crop yields and pasture growth.
There has been no improvement to drought conditions in the Western Local Land Services (LLS) Region since the August State Seasonal Update. The Combined Drought Indicator (CDI) shows that the majority of the region as being in one of the three drought categories of Drought Affected, Drought or Intense Drought (Figure 16). Conditions around the Ivanhoe district continue to intensify due to dryness and the onset of warmer temperatures after some meteorological relief was experienced in Autumn. The entire region continues to experience the continuation of poor on-ground conditions with no relief experienced so far in Spring.
The monthly NDVI anomaly data (Figure 17) indicates that the region continues to be experiencing below normal levels of greenness compared to the long term expectations. This has been driven by poor agronomic activity due to insufficient winter rain to encourage widespread agronomic growth into spring. Though below average, the NDVI suggests slightly better conditions relative to the long term comparisons in the areas that have received higher rainfall totals around Ivanhoe in autumn and the early winter months.
The time series charts (Figure 18) showing the individual response of the drought indices for Bourke, Ivanhoe, and Wentworth reflect the variation between locations. Despite not being drought breaking, Bourke experienced a positive shift in the indices during April and May. This was short lived with the indices declining due to the lack of follow up rainfall. Ivanhoe experienced similar relief in April and May but with a slightly greater magnitude initiating a short-term period of recovery. Conditions have since plateaued, and with temperatures now increasing, the indices are likely to decline without adequate rainfall in the near future. Wentworth has experienced a longer period of time where the drought indices have struggled to surpass the lowest 10th percentile. There has been little if any relief to drought conditions for a long period of time.
Drought conditions continue to impact the entire northern area of NSW with the Combined Drought Indicator (CDI) showing the region to be in one of the three drought categories of Drought Affected, Drought or Intense Drought (Figure 19). Drought intensity remains high in the area and widespread field reports continue to confirm the severity of enduring drought conditions across the region.
The monthly NDVI anomaly data (Figure 20) indicates that most of the region continues to be experiencing below normal levels of greenness compared to the long term expectations. This reflects the insufficient rainfall over recent months and corresponding poor agronomic activity.
The time series charts (Figure 21) showing the individual response of the drought indices for Moree, Walgett and Tenterfield reflect the long term trend of the indices tracking in the bottom 5th percentile of the historic range. There was a small positive rainfall shift at Tenterfield in early 2019, but the effectiveness of this rainfall was poor as indicated by the lack of response in the soil moisture and plant growth indices. All three locations show extremely low rainfall indices for the majority of 2019 and highlights the ongoing intensity and duration of drought conditions occurring in northern NSW.
The majority of the Central Tablelands, Central West, Hunter and Greater Sydney Local Land Services regions (LLS) continue to experience drought conditions. The Combined Drought Indicator (CDI) shows that most of the area remains categorised in either the Drought Affected, Drought or Intense Drought categories (Figure 22). Conditions have remained relatively stable since the August State Seasonal Update, except for the northwest of the region and around Condobolin, which have transitioned into the Intense Drought category. Parts of the Central Tablelands LLS region received useful rainfall in mid-September. This has provided the opportunity for some short term feed production, though to date there has been little change to the CDI. Timely follow up rainfall is required to provide longer term confidence of initiating drought recovery.
The monthly NDVI anomaly data (Figure 23) indicates that most of the region continues to be experiencing below normal levels of greenness compared to the long term expectations. This has been driven by poor agronomic activity over the past few months and insufficient rain to encourage agronomic growth. There has been a small improvement in parts of Central Tablelands LLS due to September rainfall, however overall this remains less than expected for this time of year.
The time series charts (Figure 24) show the individual response of the drought indices for Cowra, Condobolin and Singleton. Drought conditions have impacted all locations for an extended period of time, however the charts show some variation in the nature of the drought between the locations. There have been periods of short term relief at Singleton since February, however this has been short lived due to the lack of follow up rainfall, as reflected in the declining indices. The importance of follow up rainfall can also be observed at Cowra, where the rainfall that has been received has largely been ineffective on soil moisture and plant growth. The duration and intensity of conditions at Condobolin have been far more severe, with the drought indices all tracking below the bottom 5th percentile for the last eight months.
The majority of the South East Local Land Services (LLS) region is classified as either Drought Affected (intensifying) or Drought as shown by the Combined Drought Indicator (CDI) (Figure 25). Within this overall regional assessment, conditions are highly variable with isolated parts of the region receiving rainfall and experiencing warm conditions that promote pasture growth, for instance in areas around Goulburn. So far in Spring, there has been little change since August with any improvements despite rainfall occurring in parts of the region during mid-September. Low winter rainfall resulted in the majority of the region starting with a poor base in Spring and beneficial rainfall occurring in the region will require timely follow up falls to provide longer term drought relief. The far south of the region remains under pressure where September rainfall totals were comparatively low.
The monthly NDVI anomaly data (Figure 26) indicates that most of the region continues to be experiencing below normal levels of greenness compared to the long term expectations. This has been driven by poor agronomic activity over the past few months and insufficient rain to encourage sustained agronomic growth. Much of the plant response potential provided by the September rainfall in the region is unlikely to become apparent until the next reporting cycle.
The time series charts (Figure 27) show the individual response of the drought indices at Bega, Goulburn and Cooma. Of the three locations, Bega experienced the greatest amount of relief with a short term recovery occurring between March and June before rapidly falling below drought thresholds in July. This false recovery highlights the need for sustained follow up rainfall to create confidence of longer term drought recovery, with this region experiencing lower September rainfall totals. Both Goulburn and Cooma received some meteorological relief with rainfall occurring from April, however this rainfall has been ineffective for driving soil water and plant growth indicators above the lowest 20th percentile. Conditions plateaued during the winter period and the soil water and plant growth response to September rainfall is still being ascertained. Similar to Bega, Cooma also received low September rainfall totals.
The official National Climate Outlook for October to December was released by the Bureau of Meteorology (BoM) on 3 October 2019. Rainfall is likely to be below average across most of Australia for the remainder of 2019, with high chances of a drier October and November in particular. The north western areas of Western Australia are the exception, where there is currently a near equal chance of being wetter or drier than average.
Daytime temperatures are very likely to be warmer than average across the Australian mainland for the remainder of 2019 and early 2020. There are strong chances of warmer than average nights for the majority of the country over the next three months, however the probabilities ease to a near equal chance of warmer or cooler than average overnight temperatures in parts of the southeast and on the Queensland coast.
A positive Indian Ocean Dipole (IOD) is likely to remain the dominant climate driver for Australia until at least the end of spring, while a prolonged period of negative SAM (Southern Annular Mode) may also contribute to the dry/warm outlooks for eastern Australia during October and November.
New South Wales is forecast to have a lower chance of exceeding median rainfall for the next three months. The historical rainfall outlook accuracy at this time of year is moderate to high for NSW.
The BoM temperature outlook for October to December (Figures 29 & 30) indicates a high chance of warmer than average daytime temperatures occurring across all of NSW. Overnight temperatures are also forecast to have a higher chance of being warmer than average for most of NSW, however south eastern areas of the state have a near equal chance of experiencing warmer or cooler than average overnight temperatures.
The Bureau of Meteorology’s (BoM) El Niño–Southern Oscillation (ENSO) Outlook was released on 1 October 2019, with the forecast remaining neutral until the end of the year. Most of the atmospheric indicators are also neutral, with the exception of the Southern Oscillation Index, which is currently highly negative (details below).
The eight surveyed international climate models forecast neutral ENSO for the remainder of 2019 and into early 2020.
The 30-day Southern Oscillation Index (SOI) for the 30 days ending 29 September was -12.8. The 90 day value was -9.0. The recent negative SOI values are due to high atmospheric pressure over Darwin.
While negative values generally indicate El Niño conditions, the pattern of atmospheric pressure (high pressure over Darwin and normal pressure at Tahiti) is not consistent with an El Niño.
Monthly sea surface temperatures for September were about average in the central Pacific, warmer than average in the western Pacific, and cooler than average in the eastern Pacific. Ocean temperatures off the north coast of Australia were cooler than average, extending into the eastern Indian Ocean. Cooler waters in the eastern Indian Ocean commonly occur during a positive Indian Ocean dipole.The latest values of the three key NINO indices in the tropical Pacific for the week ending 29 September are: NINO3 -0.1°C, NINO3.4 +0.2°C and 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.
The four-month sequence of equatorial sub-surface temperature anomalies (to 28 September) shows a pattern of intensifying cool anomalies extending across the eastern equatorial Pacific. Weak warm anomalies extend to 400 m depth in the central Pacific.
The Indian Ocean Dipole (IOD) remains strongly positive with the latest weekly index value to 29 September at +1.76°C. This is the highest weekly value observed in BoM’s 2001-present dataset. The positive IOD pattern of sea surface temperatures in the Indian Ocean has remained generally consistent since late May, with warmer than average SSTs in the western Indian Ocean and cooler than average waters in the eastern Indian Ocean.
All climate models used in the BoM forecast indicate that the IOD will remain positive into December. IOD events usually dissipate by early summer with the arrival of the monsoon trough. The models indicate a slower breakdown of the IOD than usual, but it is unlikely that the positive IOD influence will persist throughout summer.
A positive IOD is associated with below-average winter-spring rainfall over southeastern Australia and warmer daytime temperatures. The positive IOD has little influence on overnight temperatures.
The current index for the Southern Annular Mode (SAM) is weakly negative and is expected to become increasingly negative over the next two weeks. A negative SAM in mid-to-late spring contributes to warmer daytime temperatures, lower rainfall, and higher wildfire risk. The negative SAM has less influence on overnight temperatures.
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:
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 Unit, which is part of the Livestock Systems Branch in DPI Agriculture.
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 (2019), Panorama Avenue, Bathurst 2795 and data which is © Commonwealth of Australia 2019, 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 Industry, Skills and Regional Development, 2019. 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 (October 2019). 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 7 Issue 9.