Prepared by NSW DPI Climate Unit
Drought conditions remain widespread across New South Wales (NSW), particularly in the entire western area of the state which is managing a prolonged drought event. The north and north west of the state are managing heightened levels of risk at this time because of the greater reliance of agriculture in this region on summer rainfall which has been extremely low for the 2018-19 season through the end of February.
A dry and warm February means that there has been little change in the overall situation in NSW since the release of the January 2019 State Seasonal Update (SSU). Localised storm rainfall has been recorded in some areas, however this has had no agronomic benefit in most regions. There are parts of the central tablelands and coastal NSW that are in drought recovery, but the rate of recovery has slowed over February and further rain is now needed to continue a positive trend.
The NSW DPI Combined Drought Indicator (CDI) provides a general regional assessment of the highly variable field conditions observable on farm. It indicates that there have been some minor shifts in the nature of the current drought, but NSW remains challenged by the agronomic and hydrological impacts of the event. Overall the CDI is unchanged since the January SSU with 99.9% of NSW experiencing drought conditions. The proportion of the state classified as being in Intense Drought (33.5%) remains similar in February, however the distribution of these areas has shifted, with some regions receiving localised intense rainfall events, and corresponding lift in the Rainfall Index. While rainfall was recorded at some meteorological stations there has been no change in agronomic and hydrological conditions (Plant Growth and Soil Water indices) and these drought indicators remain at critically low levels.
This highlights that, for most regions across the state, any rainfall received in January-February was largely ineffective due to high temperatures and evaporation. Despite the apparent easing of meteorological conditions in some regions, evident in rainfall records from the state’s monitoring network, in-field conditions observable by landholders and agronomists remain largely unchanged. These areas, largely in the Western LLS region, remain in the Drought category. Due to the long-term soil moisture deficit being experienced throughout this current event, DPI advises that these areas continue to experience equivalent levels of agronomic and hydrological impacts as those classified as being in the Intense Drought category.
Rainfall throughout February was generally inadequate for prompting any practical wide scale agronomic response across most of the state. February rainfall anomalies indicate only very isolated areas of median to above median (up to 50mm) rainfall.
Temperatures remained warm to hot throughout February with the majority of the state experiencing average to 2°C above average for daytime and overnight temperatures. Without adequate rainfall during the month and on the back of the record heat experienced throughout January, temperatures are still having a negative impact on field conditions across the majority of the state.
The dry conditions in February have continued the pressure on surface water supplies across the state. Farmers and communities, particularly in the western areas, continue to manage surface water shortages in addition to low primary productivity. In general, the lack of rainfall and high evaporation rates this month has not improved the NSW farm dam status.
Official climate forecasts released on 28 February from the Bureau of Meteorology indicate a low probability of achieving median rainfall across NSW for the March to May period. This probability of achieving median rainfall has declined significantly since the January SSU. The temperature outlook indicates a high chance of warmer than average daytime and overnight temperatures across all of NSW for the March to May period. The major climate drivers remain in a near neutral state, however El Niño predictions made in early autumn generally have lower accuracy than predictions made at alternative times of the year. Ultimately, the drought conditions are expected to continue across NSW into the near future when the combination of the less than favourable forecast and recent continuation of February drought conditions are considered.
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.
The Bureau of Meteorology reports that February rainfall was 60% below the long-term average across NSW. Large areas in western, north western and the northern tablelands regions received monthly totals of less than 25mm, with some locations in these regions experiencing their lowest February totals in history. Rainfall totals in excess of 50mm were recorded in parts of the central west, the southern ranges and along most coastal regions. Falls of above 100mm were recorded on the far south coasts, north of Sydney and the mid-north coast.
Rainfall anomalies for the month of February indicate only very isolated areas of median to above median (up to 50mm) rainfall. These areas are localised and include the central west, a small area on the mid Victorian border, the southern ranges and the far south coast. In contrast, the majority of NSW received lower than median rainfall ranging from -10mm to -200mm below the median for the month. The north east of NSW exhibited larger deficits with the northern coastal region being the most extreme indicating a deficit of -200mm for a significant proportion of the region. February rainfall has generally been inadequate for a positive agronomic response.
Temperatures during February remained hot with daytime and overnight temperatures being average to above average across the state. The Bureau of Meteorology indicated that temperatures in February continued the run of 22 consecutive months of warmer than average daytime temperatures. Average daytime temperature anomalies were generally 0-2°C above average and ranged from 24°C on the south coast, southern ranges, central and northern tablelands to 39°C in the north west of the state. Alpine regions were slightly cooler and ranged between 18-24°C.
The majority of NSW also experienced higher than average overnight temperatures particularly in the central north region where anomalies were 0-3°C above average. Overnight temperatures ranged between 12-27°C for the majority of NSW, except for alpine regions which recorded temperatures between 6-12°C, while parts of the Central Tablelands Local Land Services region recording overnight temperatures between 9-12°C.
The monthly NDVI anomaly data (Figure 5) continues to show that the majority of NSW is experiencing lower than normal levels of plant condition (greenness). These values highlight the very poor agronomic conditions where crops and pastures remain under stress. The central and southern tablelands are exhibiting higher levels of plant activity as result of receiving consecutive storm events occurring since the start of the calendar year.
Critically low dam levels continue to persist across most of NSW as of 20 Feb 2019 (Figure 6). There has been a slight improvement in dam levels through the Central Tablelands and the alpine region along the Riverina-South East border, reflecting the pattern of recent rainfall events. While some parishes in the Western LLS have shown slight improvements since last month, this is likely due to manual filling from bore water resources. Overall, water resources remain critical, particularly in the Western, northern Central West, and North West LLS regions. For further information more details can be found at the Drought Hub.
Large parts of NSW were affected by dust storms on 12 February. More information about dust storms and their current frequency can be found in the Department of Environment and Heritage community dust watch program.
Two significant fires occurred during February in the north of the state at Tingha (near Inverell) and Tabulam (near Casino.
Crop damage was reported along parts of the far northeast due to the damaging winds associated with tropical cyclone Oma.
The Soil Water Index (SWI, Figure 7) remains extremely low across most of the state with little change since the January report.
Similar to the SWI, the Plant Growth Index (PGI, Figure 8) has remained extremely low across the state. This highlights the poor agronomic conditions that continue to impact primary production for NSW.
Values for the Rainfall Index (RI, Figure 9) generally remain below average to extremely low across NSW. Some areas in the western, central western and south coast regions have observed a modest improvement since the January SSU, however as noted for the SWI and PGI above, there has generally been no agronomic benefit and on-ground drought conditions have not improved.
The proportion of NSW experiencing a drier trend has continued to increase significantly since the January SSU. The Drought Direction Index (DDI, Figure 10) shows that there only small areas of NSW showing a wetter trend, occurring in isolated patches from the central west extending towards the southeast of the state.
Changes in the individual drought indicators may have occurred since this update was released. For the most current information, please visit Drought Hub.
Figure 11 displays the CDI status for each individual Local Land Services region to 28 February 2019.
Since the January State Seasonal Update (SSU), Intense Drought conditions have retracted in the east of the Western Local Land Services (LLS) region, as well as throughout the Murray, Riverina and southern Central West LLS regions. Despite the CDI showing a change in the nature of the drought event over the last 3 weeks in these areas, there has been no practical relief to on-ground agronomic conditions. Conditions in the North West and Northern Tablelands LLS regions have deteriorated, with the majority of these regions now classified as being in the Intense Drought category. The improvement to conditions observed in January along the coast have plateaued, particularly in some areas of the North Coast and South East LLS regions where Intense Drought has quickly emerged since the last SSU. This highlights the ongoing requirement for significant follow up rainfall to initiate a longer term recovery trajectory.
The Murray and Riverina Local Land Services (LLS) regions continue to experience drought conditions with the large majority of the region being in one of the three drought categories of Drought Affected, Drought or Intense Drought (Figure 12). The extent of the area classified as being in Intense Drought has receded since the January State Seasonal Update (SSU) as a result of some isolated convective storm activity influencing the Rainfall Index (RI). In some instances, this storm activity has triggered the RI to rise above the lower threshold and change the drought classification from the January SSU (Figure 14), however the agronomic and hydrologic drought indicators (Plant Growth and Soil Water Indices) remain critically low.
Despite the storm activity and shift of drought classification, there has generally been little improvement of plant conditions across these LLS regions. The monthly NDVI anomaly data (Figure 13) shows that the eastern extremities of both LLS regions and localised areas around Griffith and Coleambally have shown a small improvement as a result of the rainfall, however plant activity (greenness) remain at generally low levels relative to the long term expected averages.
The Western Local Land Services (LLS) region continues to experience drought conditions with the entire area being in one of the three drought categories of Drought Affected, Drought or Intense Drought (Figure 15). The Combined Drought Indicator (CDI) shows that the area in Intense Drought has receded since the January State Seasonal Update (SSU). Isolated storms occurring earlier in February triggered a positive Rainfall Index (RI) response as observed in Figure 17, where the RI has risen above the lower threshold for some areas. This small amount of meteorological relief has not translated into any significant crop/pasture response, and on ground conditions have not improved. The sparse meteorological network is not dense enough to accurately capture storm rainfall on a farm by farm basis and available field reports support that there has been no tangible improvement in physical conditions.
The monthly NDVI anomaly data (Figure 16) also confirms the lack of response to rainfall and indicates that the region continues to experience below average levels of greenness. Minimal grass cover across large parts of the region continue to be of concern, with environmental risks such as dust storms and erosion losses remaining at extremely high levels.
The North West, Northern Tablelands and North Coast Local Land Service (LLS) regions have all observed a significant deterioration in conditions (Figure 18) since the January State Seasonal Update (SSU). The majority of the North West and Northern Tableland LLS regions are now classified as being in Intense Drought. The small Non-drought classification for the Northern Tableland LLS region evident in January SSU has also reduced in area and has been reclassified with downgraded conditions. A significant area in the north and west of the North Coast LLS region has also declined into the Intense Drought classification since the January SSU. The coastal areas in the North Coast LLS region that were showing signs of Recovery or Non-drought conditions have been adversely affected throughout February and are now experiencing a re-intensification of drought conditions.
The monthly NDVI anomaly data (Figure 19) indicates that the North West, Northern Tablelands and North Coast LLS regions continue to experience below average levels of greenness. The North Coast experienced a rapid deterioration in average greenness since January and now exhibits very low levels of plant activity relative to average. This is supported by the on-ground conditions that have been reported to NSW DPI this month.
Conditions across the Central Tablelands, Central West, Hunter and Greater Sydney Local Land Services (LLS) regions (Figure 21) have generally remained stable since the January State Seasonal Update (SSU). Conditions have intensified with an expansion of Intense Drought in the northwest of the Hunter LLS region to the north of Merriwa and Aberdeen. In the Central West LLS region, the south west area has observed a reduction in the area classified as Intense Drought, however this has been triggered by some meteorological relief which has not translated into any significant on-ground improvements for soil moisture or plant activity (Figure 23). In the Central Tablelands LLS region, areas around Bathurst, Mudgee and Lithgow remain relatively stable where a degree of meteorological and agronomic recovery due to repeated storm events has continued.
The monthly NDVI anomaly data (Figure 22) indicates that the entire area, with the exception of the Central Tablelands, is experiencing below average levels of greenness. The repeated storm events occurring in the central region of the Central Tablelands has contributed to average to slightly above average levels of plant activity, reflecting an improvement from January. An improvement has also been observed for parts of the other LLS regions, especially as the proximity to the Central Tablelands LLS region increases, however levels of greenness are still generally below average.
There were variable conditions observed for the South East Local Land Services (LLS) region during February (Figure 24). Non-drought and Recovering areas on the coast observed in January have remained stable, however there has been a general intensification of drought conditions immediately inland from the coast. A significant area in the north of the region has also been reclassified into the Intense Drought category. The existing area previously classified as being in Intense Drought for the Monaro region did exhibit a reduction this month as a result of rainfall triggering a positive Rainfall Index (RI) response, however follow up rainfall will be required to assist any sustained agronomic recovery.
The monthly NDVI anomaly data (Figure 25) indicates that the majority of the South East LLS region shows poor plant activity, however there have been some positive responses due to rainfall. The Monaro region, an area around Boorowa and a portion of the LLS region between Yass and Braidwood is showing average to slightly above average levels of greenness for February. Low levels of plant activity are more severe closer to the coast, especially between Ulladulla and Bega.
The Bureau of Meteorology released an official national climate outlook for March to May on 28 February 2019. The outlook shows that the autumn period is likely to be drier than average across the majority of the eastern half of Australia. This includes Queensland, New South Wales, Victoria, northern and eastern Tasmania, eastern South Australia and the southern two-thirds of the Northern Territory. In contrast the majority of Western Australia has a near equal chance of being wetter or drier than average with parts of the Gascoyne and the Pilbara more likely to be wetter than normal. The forecast accuracy for rainfall at this time of year is mixed for the March to April period. A moderate accuracy occurs for most of the country, however remains low near the New South Wales-Queensland border, western Tasmania and across the southeast and interior of Western Australia.
The outlook shows March to May daytime and overnight temperatures continue to have a very high chance (>80%) of being warmer than average for the majority of Australia.
The March to May rainfall outlook indicates that all of New South Wales (NSW) is likely to experience drier than average conditions (Figure 27). The outlook indicates that the majority of NSW is predicted to have up to a 35% chance of exceeding median rainfall over the next three months, with lower probabilities (<35%) estimated for the southern slopes and tablelands, the far northern slopes extending onto the plains and around the greater Sydney region. Only small areas are predicted to have a slightly higher probability (40%) of receiving median rainfall, including parts of the mid north and north coast and isolated pockets in the central far west region towards the South Australian border.
The temperature outlook (Figures 28 & 29) indicates that there is a very high chance of warmer than average daytime and overnight temperatures across the entirety of NSW for the next three months. There is an 80% chance of warmer than average daytime temperatures occurring across NSW. The forecast for overnight temperature is similar across the northern half of the state and extending to the tablelands and coastal regions. Overnight temperatures are also forecast to be higher in the southwestern portion of the state, with the probability of warmer than average overnight temperatures ranging between 60-70%.
As of 5 February 2019, the Bureau of Meteorology’s ENSO assessment remains neutral. The ENSO outlook remains at El Niño Watch, with a 50% chance of El Niño developing during the southern hemisphere autumn or winter. Over the past fortnight, tropical Pacific sea surface temperatures (SSTs) have warmed and are approaching El Niño thresholds. Weakened trade winds, associated with an active period of the Madden-Julian Oscillation (MJO) and the impacts of tropical cyclone Oma and typhoon Wutip have been key drivers of this recent warming of the ocean’s surface. It appears that the trade winds have returned to near average as the MJO moves eastwards, possibly suggesting that ocean temperatures may also ease over the next fortnight.
Five of eight climate models indicate the central Pacific is likely to reach near borderline or weak El Niño levels during autumn, with four models remaining above threshold levels into winter. However, El Niño predictions made in early autumn tend to have lower accuracy than predictions made at other times of the year and therefore current forecasts of the ENSO state beyond May should be interpreted caution.
The 30-day SOI value has continued to fall and has been within the El Niño range for nearly two weeks. (30 day value is -12.5, 90 day value is currently neutral at -2.2 as of 3 March 2019). This negative value should be considered with caution as SOI values during the Australian monsoon season can be volatile.
Cloud levels at the junction of the equator and the International Date Line have continued to fluctuate over the past month, however, they have been above average since December 2018, and well above average during February 2019. Typically, cloud levels would be well above average during an El Niño event.
Trade winds have been weak in previous weeks as a result of an active phase of the Madden-Julian Oscillation (MJO). This influence has now weakened, with forecasts suggesting that average or strengthened trade winds will resume in the western Pacific region over the next few weeks. During El Niño, there is a sustained weakening, or even reversal, of the trade winds across much of the tropical Pacific. Conversely, during La Niña, there is a sustained strengthening of the trade winds.
Monthly sea surface temperature (SST) anomalies for February (Figure 31) in the central to eastern equatorial Pacific Ocean and close to average in the western Pacific Ocean. The February values for NINO3 were +0.5 °C, NINO3.4 +0.6 °C, and NINO4 +0.8 °C. Recent NINO region values are close to El Niño thresholds, but would need to warm and persist for El Niño conditions.
Subsurface temperatures as of 5 March 2019 are anomalously warm in the top 200m of the western to central equatorial Pacific Ocean and anomalously cool in the top 150m of the eastern equatorial Pacific. Overall subsurface warm anomalies have decayed over the last 4 months.
The Indian Ocean Dipole (IOD) has transitioned into a negative phase over the past two weeks, with the indicator currently at -0.48°C, although analysis of the ensemble of international climate models suggests this may be short-lived. The IDO typically has little effect on Australian climate between December and April.
The Southern Annular Mode (SAM) is currently negative and is expected to return to neutral values over the next two weeks. A negative SAM causes an expansion of the westerly wind belt towards the equator and causes high pressure systems to persist over southern Australia, restricting rainfall. A neutral SAM is unlikely to impact Australian rainfall.
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 Drought Hub.
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 2 below.
Table 2: 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 (February 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 2