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NSW State Seasonal Update - January 2019

Prepared by NSW DPI Climate Unit

During January 2019 drought conditions across New South Wales (NSW) have re-intensified  despite some storms and localised easing of the drought on the eastern seaboard. There has been no break from drought conditions in the west of the state, further prolonging this severe event for many producers.

The Combined Drought Indicator (CDI) shows that 99.8% of NSW is experiencing drought conditions, with 36.8% being classified as Intense Drought, 44.2% as Drought and 18.8% categorised as Drought Affected. There has been an increase in the area classified as Intense Drought over the last month particularly in the north west, western and southern areas of the state. Areas that had been recovering in December have had a very dry January, and are now deteriorating particularly in the North West, North Coast, Hunter and Greater Sydney Local Land Services (LLS) regions. The South Coast is the exception where there has been a slight easing of conditions over January, but follow up rainfall is needed to ensure the improvement in conditions continues.

The breakdown of drought by the NSW CDI provides a general assessment of the complex pattern of in-field conditions. Numerous climatic records were broken during January where some areas observed the lowest January rainfall totals in a 100 year history, while many other areas received their lowest totals for the last 20 years. The drier areas of the state relative to average included the northeast, far west and southwest regions. In contrast, some areas in the northern and central tablelands were exposed to intense storm activity that provided isolated 20 year record breaking January rainfall. Given the high rainfall intensities and compromised infiltration rates much of this rainfall was not effective for soil water recharge and pasture response.

Extreme heat was also experienced across NSW in January with 90% of the state experiencing its warmest January in history. This heatwave exacerbated the effects of ongoing dryness or further compromised the ability of areas that have received rainfall to make any significant improvements. The extreme heat has also had an impact on the little area of summer crop that has been planted, while placing further pressure on stock water resources and demand.

The available hydrological data from the NSW farm dam survey confirms that surface water supplies remains critically low for many areas in western regions. This continues to reinforce that farmers and communities are still managing issues beyond the poor agronomic conditions, with water reserves remaining critically low.

Official climate forecasts from the Bureau of Meteorology show that the three month rainfall outlook for February to April indicates a near equal chance of wetter or drier than average conditions across NSW. The temperature outlook indicates that there is an increased chance of warmer than average daytime and overnight temperatures across all of NSW for the next three months. The major climate drivers remain in a near neutral state and we are in a time of the year when the skill level of seasonal climate forecasting is low. Given the current forecasting in conjunction with the recent deterioration of conditions across most of the state, the drought event is expected to continue across NSW into the near future.

For an accessible explanation of this chart contact the author scott.wallace@dpi.nsw.gov.au

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.

Rainfall

Rainfall was well below average across much of New South Wales, particularly in the northeast and southern inland regions of the state. Some localities in these regions received their lowest total January rainfall on record with others experiencing the lowest in the last 20 years. Rainfall totals ranged from 0 - 25 mm in the western and northeastern parts of the state. Due to frequent isolated thunderstorms, some areas of the northern Central Tablelands and western Hunter LLS regions experienced above average rainfall, with some localities achieving their highest January rainfall totals in the last 20 years. Rainfall totals above 200 mm were recorded in the Central Tablelands, with falls of up to 100 mm in the Northern Tablelands, Central West and South East LLS regions.

For an accessible explanation of this chart contact the author scott.wallace@dpi.nsw.gov.au

Temperature

Due to a prolonged widespread heatwave during January 2019, 90% of New South Wales experienced its warmest January on record, with statewide mean, maximum, and minimum January temperatures all the highest on record. Average daytime temperatures ranged from 30°C near the coast to upwards of 45°C in the northwest, with anomalies of over 6°C. Average overnight temperatures ranged from 15°C in the southeast to 30°C in the northwest, with anomalies of up to 6°C above average. Alpine regions experienced slightly cooler mean overnight temperatures.

For an accessible explanation of this chart contact the author scott.wallace@dpi.nsw.gov.au

For an accessible explanation of this chart contact the author scott.wallace@dpi.nsw.gov.au

Normalised Difference Vegetation Index (NDVI) Anomaly

The monthly NDVI anomaly data (Figure 5) indicates that the majority of NSW continues to be experiencing lower than normal levels of greenness. These values are indicative of very poor agronomic conditions where crops and pastures are under stress.

For an accessible explanation of this chart contact the author scott.wallace@dpi.nsw.gov.au

Farm Dam Water Status

As of 20 January, farm dam levels remain critically low across most of NSW, particularly in the west and south of the state. The farm dam survey indicates that water levels in the North Coast and Northern Tablelands may have declined since the last update on 8 December. Isolated improvement in farm dam levels has occurred in the Central Tablelands, Greater Sydney, eastern Hunter, and northern South East LLS regions, due to isolated thunderstorms moving across these areas.

For an accessible explanation of this chart contact the author scott.wallace@dpi.nsw.gov.au

Extreme events

The Bureau of Meteorology have identified that January 2019 was the warmest month on record for New South Wales. 90% of the state experienced its warmest January record, with mean, maximum, and minimum temperatures all the highest on record. The record heat was associated with persistent heatwave conditions that affected large areas of the country in January, peaking in New South Wales from 14 to 18 January. During this time, NSW had 5 consecutive days where the Statewide-averaged daily maximum temperature was 40 °C or higher, with many individual sites also exceeding daily overnight temperature records.

More information about January 2019 temperatures can be found in the Bureau of Meteorology’s monthly climate summary.

The frequency of dust storms increased across many regions including a severe dust storm which affected the Riverina LLS on 8 January. More information about dust storms and their current frequency can be found in the Department of Environment and Heritage community dust watch program.

Rainfall Index

Values of the Rainfall Index (RI, Figure 7) across most of New South Wales remain at below average to extremely low. While areas of the Central Tablelands, Hunter, and Greater Sydney have shifted towards average values, the RI has decreased in much of the Western, Riverina, Murray and North Coast LLS regions.

For an accessible explanation of this chart contact the author scott.wallace@dpi.nsw.gov.au

Soil Water Index

The Soil Water Index (SWI, Figure 8) remains extremely low across most of the state with little change since the last report. Areas in the North Coast experiencing average SWI values have decreased slightly since the December State Seasonal Update.

For an accessible explanation of this chart contact the author scott.wallace@dpi.nsw.gov.au

Plant Growth Index

Similar to the SWI, the Plant Growth Index (PGI, Figure 9) has remained extremely low across most of the state. The Central Tablelands has seen the greatest improvement in PGI, though values are still considered below average.

For an accessible explanation of this chart contact the author scott.wallace@dpi.nsw.gov.au

Drought Direction Index

The area of the state experiencing a drier trend as indicated by the Drought Direction Index (DDI, Figure 10) has increased significantly since the last State Seasonal Update. With the exception of the Central Tablelands, South East and part of the Central West, which still exhibit slight wetter trends, most regions have shifted towards drying trends.

For an accessible explanation of this chart contact the author scott.wallace@dpi.nsw.gov.au

Changes in the individual drought indicators may have occurred since this update was released. For the most current information, please visit Drought Hub.

CDI status for the regions

Figure 11 displays the CDI status for each individual Local Land Services region to 31 January 2019.

For an accessible explanation of this chart contact the author scott.wallace@dpi.nsw.gov.au

Murray and Riverina regions

The Murray and Riverina Local Land Services (LLS) regions continue to experience drought conditions with the entire region being in one of the three drought categories of Drought Affected, Drought or Intense Drought (Figure 12). The extent of area in Intense Drought has increased across the central parts of the region and an isolated area of Intense Drought has also formed in the west of the Murray LLS region.

The monthly NDVI anomaly data (Figure 13) indicates that there no improvement of plant conditions across the LLS regions relative to the long term expected average. There are some localised areas of greenness to the east of the region, however this is has an isolated distribution and the extent has declined since the last State Seasonal Update in December.

For an accessible explanation of this chart contact the author scott.wallace@dpi.nsw.gov.au

For an accessible explanation of this chart contact the author scott.wallace@dpi.nsw.gov.au

For an accessible explanation of this chart contact the author scott.wallace@dpi.nsw.gov.au

Western region

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 expanded since the December State Seasonal Update, with over 35% of the region currently categorised as Intense Drought. Scattered storms have brought some relief to farms in the south of the region, although the meteorological network is not dense enough to accurately capture storm rainfall on a farm by farm basis. Available field reports indicate that many livestock producers in this region are still feeding livestock.

The monthly NDVI anomaly data (Figure 16) indicates that the region continues to experience below average levels of greenness, with conditions deteriorating since the December State Seasonal Update. 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.

For an accessible explanation of this chart contact the author scott.wallace@dpi.nsw.gov.au

For an accessible explanation of this chart contact the author scott.wallace@dpi.nsw.gov.au

For an accessible explanation of this chart contact the author scott.wallace@dpi.nsw.gov.au

North West, Northern Tablelands and North Coast regions

Conditions across the North West, Northern Tablelands and North Coast Local Land Services (LLS) regions are varied. Generally conditions have deteriorated in all regions despite some isolated areas in eastern parts continuing to show signs of recovery. The North West LLS region has seen the greatest decline in conditions since the December State Seasonal Update (SSU), with approximately 75% of the region in the Intense Drought category. The Northern Tablelands LLS region has remained relatively stable since the last SSU, however the area of Intense Drought has expanded around the Tenterfield region.

The North Coast LLS region continues to show isolated signs of recovery, particularly around Ballina and Coffs Harbour, however the Combined Drought Indicator shows that the areas in the Drought Affected category are currently intensifying.

The monthly NDVI anomaly data (Figure 19) indicates that the North West, Northern Tablelands and North Coast LLS regions have experienced a deterioration in average conditions since the December State Seasonal Update and the entire area is experiencing below average levels of greenness. This reflects the on-ground conditions that have been reported to NSW DPI this month.

For an accessible explanation of this chart contact the author scott.wallace@dpi.nsw.gov.au

For an accessible explanation of this chart contact the author scott.wallace@dpi.nsw.gov.au

For an accessible explanation of this chart contact the author scott.wallace@dpi.nsw.gov.au

Central Tablelands, Central West, Hunter and Greater Sydney regions

Conditions across the Central Tablelands, Central West, Hunter and Greater Sydney Local Land Services (LLS) regions have generally remained stable since the December State Seasonal Update (SSU). There has been an expansion of Intense Drought in the Central West LLS region, particularly around Coonamble, Grenfell, Parkes, south of Dubbo and to the west of Nyngan.  There are areas around Bathurst, Mudgee and Lithgow which have had a degree of meteorological recovery due to repeated storm events. Given high summer evaporation rates and low levels of rainfall infiltration, soil moisture remains below average and these areas remain in the Drought Affected category.

The monthly NDVI anomaly data (Figure 22) indicates that the regions have experienced a deterioration in conditions since the December State Seasonal Update and the entire area is experiencing well below average levels of greenness. This reflects the on-ground conditions that have been reported to NSW DPI this month, with very low feed availability and ground cover. There are small isolated areas that are experiencing average to slightly above average levels of greenness, which reflects areas that were showing strong recovery last month. However the strength of this greenness has deteriorated during January.

For an accessible explanation of this chart contact the author scott.wallace@dpi.nsw.gov.au

For an accessible explanation of this chart contact the author scott.wallace@dpi.nsw.gov.au

For an accessible explanation of this chart contact the author scott.wallace@dpi.nsw.gov.au

South East region

Conditions across the South East Local Land Services (LLS) region have generally remained stable since the December State Seasonal Update (SSU), except for an area in the south of the region where there has been an expansion in the Intense Drought category. A large area in the Intense Drought category now spans from Cooma to Jindabyne, and east towards Bombala.

The monthly NDVI anomaly data (Figure 25) indicates that the South East LLS region has experienced a deterioration in average conditions since the December State Seasonal Update. There are some patches of slightly above average greenness near Bombala, Murrumbateman and Cooma, however these are isolated and generally the entire area is experiencing below average levels of greenness. This deterioration of the level of greenness is particularly evident in the central and eastern part of the region.

For an accessible explanation of this chart contact the author scott.wallace@dpi.nsw.gov.au

For an accessible explanation of this chart contact the author scott.wallace@dpi.nsw.gov.au

For an accessible explanation of this chart contact the author scott.wallace@dpi.nsw.gov.au

Official national outlook

The official national climate outlook for February to April was issued by the Bureau of Meteorology on 31 January 2019. The outlook shows that Western Australia, parts of the Northern Territory, the southern area of South Australia and a majority of eastern Queensland are likely to be drier than average over the next three months. Elsewhere there is a near equal chance of drier or wetter than average conditions.

The outlook shows February to April daytime and overnight temperatures continue to have an increased chance of being warmer than average across all of Australia. There is an exception for parts of the western coastline of Western Australia and south eastern South Australia, where a near equal chance of average overnight temperature is predicted.

NSW outlook

For the majority of New South Wales, the three month rainfall outlook (Figure 27) for February to April indicates a near equal chance of wetter or drier than average conditions. The northeast corner of NSW is showing an increased chance of drier than normal conditions. In contrast, the south and central coastal areas extending into the tablelands, including a small portion in the east of the Central West, have a slightly increased chance of wetter than average conditions.

For an accessible explanation of this chart contact the author scott.wallace@dpi.nsw.gov.au

The temperature outlook (Figures 28 & 29) indicates that there is an increased chance of warmer than average daytime and overnight temperatures across all of NSW for the next three months, with the chance of warmer than average daytime temperatures currently above 70%. A similar trend is forecast for overnight temperatures, with an above 75% chance of warmer than average temperatures.

For an accessible explanation of this chart contact the author scott.wallace@dpi.nsw.gov.au

For an accessible explanation of this chart contact the author scott.wallace@dpi.nsw.gov.au

Climate drivers

ENSO

As of 5 February 2019, the Bureau of Meteorology’s ENSO assessment is currently neutral with the ENSO outlook remaining at El Niño Watch, with a 50% chance of El Niño developing during the southern hemisphere autumn or winter. Pacific Ocean sea surface temperatures (SSTs) have cooled slightly though remain warmer than average. While most atmospheric indicators of ENSO are neutral, trade winds are weaker than average and have also shown a reversal of prevailing direction (typically easterly) in many instances across the central and western Pacific. With the forecast for these winds to remain weaker to persist, further warming of the tropical Pacific is likely.

Three of the eight international climate models suggest that El Niño may establish by mid-2019. It should be noted that outlooks at this time of the season (spanning Autumn) tend to have a lower accuracy than at other times of the year.

Southern Oscillation Index and other indicators

The 30-day SOI value as of 3 February was positive (30 day value is +0.7, 90 day value is +3.8) but is in the range that is considered neutral.

Cloud levels at the junction of the equator and the International Date Line have fluctuated around average during over the past few months, however has tended to be above average during December and January. Typically, cloud levels would be well above average during an El Niño event.

Trade winds have been weaker than average, or even reversed over the western Pacific.  Westerly winds are a reversal of the usual easterlies and can be associated with El Niño conditions.  Model outlooks show that the westerly anomalies may persist, potentially reinforcing El Niño conditions.

For an accessible explanation of this chart contact the author scott.wallace@dpi.nsw.gov.au

Sea surface temperatures

Monthly sea surface temperature anomalies (SST) for January (Figure 31) remained warmer than average across the equatorial Pacific Ocean and for a large part of the southern Pacific around the International Date Line. The January values were +0.5°C for NINO3, +0.5°C for NINO3.4, and +0.7°C for NINO4.

For an accessible explanation of this chart contact the author scott.wallace@dpi.nsw.gov.au

Sea Sub-surface Temperatures

Sub-surface temperatures as of 3 February (Figure 32) indicate warmer than average anomalies in the top 200m across the western half of the equatorial Pacific Ocean. Warmer sub-surface temperatures in this region have been associated as one of the precursors to developing an El Niño event with sub-surface temperature likely to be warmer as a result of the weaker trade winds.

For an accessible explanation of this chart contact the author scott.wallace@dpi.nsw.gov.au

Indian Ocean

The Indian Ocean Dipole (IOD) is currently neutral and has very little effect on Australian climate between December and April.

Southern Ocean

The Southern Annular Mode (SAM) is currently weakly positive and is expected to remain positive over the next two weeks. Positive SAM in summer tends to promote synoptic rainfall across southern Australia.

How does it work?

For an accessible explanation of this chart contact the author scott.wallace@dpi.nsw.gov.au

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:

  • 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 2 below.

Table 2: The way in which the indicators are combined to form the CDI is described

CDI Phase

Technical definition

Description - typical field conditions

Intense Drought

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.

Drought

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.

Recovering

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.

Non-drought

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 (2018), Panorama Avenue, Bathurst 2795 and data which is © Commonwealth of Australia 2018, 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 (January 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 1