The seasonal outlooks presented in this report are obtained from the Australian Bureau of Meteorology & other sources. 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 & decision making. Changes in seasonal outlooks may have occurred since this report was released. Outlook information was up to date as at 16 June 2015.

Changes in seasonal outlooks may have occurred since this report was released. Outlook information was up to date as at 3rd December 2013.

NSW Climate Summary - June 2015Summary Seasonal outlook Current

Outlook Previous Outlook

Rainfall (quarter) Drier (northern, central, eastern NSW) Neutral (far west, far south west, far north east)

Wetter

Max Temperature (quarter)

Near neutral (far west, far south west) Warmer (northern, eastern, central NSW)

Cooler (western and areas of central) Near neutral (southern, eastern, areas of central) Warmer (far south east)

Min Temperature (qtr) Warmer (northern, eastern, southern, south eastern NSW) Near neutral (central areas of far west, areas of central NSW)

Warmer

ENSO

ENSO (overall) El Niño El Niño

BoM ENSO Tracker Status

El Niño El Niño

SOI Negative Negative

Pacific Ocean (NINO3.4)

Warm (Above El Niño thresholds)

Warm (Above El Niño thresholds)

Indian Ocean (IOD) Neutral Neutral

Southern Annular Mode (SAM/AAO)

Weakly negative – near neutral

Near neutral – weakly negative

Source: Derived from information provided by the Australian Bureau of Meteorology and the US National Oceanic & Atmospheric Administration.

Seasonal outlook (Source: Bureau of Meteorology)

Between June to August, drier than normal conditions are likely over most of eastern, central and northern NSW. Warmer than normal daytime temperatures are likely over the northern, eastern and central areas of NSW. There is a near equal chance of cooler or warmer than normal daytime temperatures for areas of the far west and far south west. Warmer than normal daytime temperatures are over eastern, northern and areas of

central and southern NSW. There is a near equal chance of cooler or warmer than normal overnight temperatures for areas of the central west, far west and far south west.

NSW Climate Summary - June 2015

2 NSW Department of Primary Industries, June 2015

ENSO (Source: Bureau of Meteorology & International Research Institute for Climate and Society)

An El Niño event has commenced and is likely to persist through winter and spring. The Bureau’s ENSO tracker status is at ‘El Niño’. NOAA CPC/IRI indicated that (based on their thresholds) the El Niño event is currently weak to moderate, although there is uncertainty about how strong it may become. Warm sea surface temperature anomalies extend across the eastern and central equatorial Pacific and temperatures are well above the Bureau’s El Niño thresholds. Sub-surface warm temperature anomalies remain across most of the central to eastern Pacific, warming the sea surface. A cool anomaly is present at depth in the west. The SOI has been negative but recently returned to the neutral range. This is due to local weather factors. Westerly wind anomalies extended across the western and central equatorial Pacific during the month. Cloud at the junction of the International Date Line and equator is moderately high. The trade winds and cloud conditions are indicative of ocean-atmosphere coupling in an El Niño event.

NOAA CPC/IRI remains on ‘El Niño advisory’, flagging an El Niño event. The CPC/IRI consensus ENSO forecast probabilities indicates that about 97% of global climate models consider El Niño conditions are likely to continue into winter, and over 85% through spring and into summer. The CPC/IRI uses a NINO3.4 anomaly of +0.5°C as an El Niño threshold, while the Bureau of Meteorology uses +0.8°C.

The Bureau of Meteorology’s POAMA outlook (as at 7 June) indicates that the sea surface temperatures in the NINO3.4 Pacific Ocean region are likely remain above the El Niño thresholds during winter and spring. All eight climate models surveyed by the Bureau (as at 16 June) indicate sea surface temperatures are likely to remain well above the Bureau’s threshold in July to November.

Monthly Sea Surface Temperatures (Source: NOAA & Bureau of Meteorology)

Warm sea surface temperatures anomalies extend across the central and eastern equatorial Pacific, and strengthened in the east during May. The most recent monthly temperature anomaly value in the key NINO3.4 region is +1.03°C for May, an increase from +0.78°C for April. The weekly value to 14 June is +1.31°C.

Monthly Sub-surface Temperatures The sub-surface sea temperatures show the eastwards progression of a strong warm anomaly across the equatorial Pacific since early in the year (a downwelling Kelvin wave) and its warming of the sea surface. Sub-surface warm anomalies now extend across the central and eastern equatorial Pacific. A small cool anomaly remains at depth in the west.

Southern Oscillation Index (SOI) (Source: Bureau of Meteorology & Queensland Department of Science, Information Technology, Innovation & the Arts)

The Southern Oscillation Index (SOI) fell during mid-late March to be strongly negative, returned to neutral levels in mid-April and fell again in early May. It has since returned to neutral levels. On 31 May, the 30-day value

NSW Climate Summary - June 2015

3 NSW Department of Primary Industries, June 2015

was negative at -13.7 but increased to +0.6 on 14 June. This is due to local weather factors rather than climatic influences.

Values of between -8 and +8 indicate neutral conditions, sustained values above +8 may indicate a La Niña event, and sustained values below -8 may indicate an El Niño event.

Indian Ocean Dipole (IOD) (Source: Bureau of Meteorology)

The Indian Ocean Dipole (IOD) is currently neutral. The IOD index value is +0.13°C for the week ending 14 June.

The Bureau of Meteorology’s POAMA model outlook indicates IOD index values at neutral (although high) levels during mid-late winter and spring. Two climate models surveyed by the Bureau currently favour a near-positive IOD in July and a positive IOD in September. One model favours a positive IOD in November. A negative IOD increases the chances of above normal rainfall during winter and spring across southern and much of western and central NSW. A positive IOD increases the chances of below normal rainfall.

Sub-Tropical Ridge (STR) (Source: NOAA & Bureau of Meteorology) The sub-tropical ridge in the 30 days to 15 June was at close to the normal latitude for the time of year, although slightly further north. Atmospheric pressure over NSW during May was near normal in the south east, slightly higher in eastern NSW and higher in the west, as indicated on NOAA and Bureau of Meteorology mean sea level pressure charts. High pressure in the west of may block rainfall from moving across the state.

The sub-tropical ridge is a zone of high pressure which between January and March is normally located south of Australia at about 38°S to 39°S, and can tend to suppress cold front activity. During June to September, it generally moves northwards to around 30°S to 32°S

allowing cold fronts to extend further into southern Australia. It has most effect on winter rainfall.

Cloudiness and trade winds (Source: Bureau of Meteorology)

Levels of cloud at the junction of the International Date Line and equator over the last month have generally been consistent with an El Niño event, as have the low levels across Indonesia. Trade winds in the western and central equatorial Pacific continue to show a weakening and reversal consistent with an El Niño event.

Southern Annular Mode (SAM) (Source: Bureau of Meteorology [experimental] & NOAA)

The experimental Southern Annular Mode or Antarctic Oscillation (AAO) index was weakly positive for most of May and is weakly negative at 14 June. The outlook from POAMA indicates the SAM index will remain weakly negative till late June. The NOAA outlook suggests a return to weakly positive values in late June.

A negative SAM indicates an expansion of the belt of strong westerly winds towards the equator, resulting in more or stronger low pressure systems across southern Australia and potentially increased rainfall. A positive SAM indicates the contraction of the belt of strong westerly winds towards Antarctica and higher pressures over southern Australia, and can result in stable, drier conditions.

NSW Climate Summary - June 2015

4 NSW Department of Primary Industries, June 2015

Conditions during May Rainfall (Source: Queensland DSITIA)

Rainfall across NSW ranged between 1-402 mm during May, with the heaviest falls over the mid-north to north coast. Areas of the far south west, central and western Riverina and the far south east received below average relative rainfall. Relative rainfall during May was above average or above across 80 per cent of NSW.

Soil moisture (Source: CSIRO)

Modelled topsoil moisture levels improved slightly across western NSW, declined slightly across areas of central NSW and the south east, remained low in the western Riverina and improved along the coast from the Illawarra to the north. Relative to historical records, levels were above average across much of eastern NSW, average across most of central and western NSW and below average in the central and western Riverina.

Modelled subsoil moisture levels were generally stable, remaining low in areas of the north and west but increasing along the coast. Relative to historical records, subsoil moisture was below average across much of the north west and areas of the northern tablelands, Liverpool plains, central tablelands and Riverina.

Pasture growth (Source: Queensland DSITIA)

Relative pasture growth during May was similar to April, although it declined in areas of the south west and the western Riverina. Across the central to north coast and the eastern fall, it remained near average and remained well above average across areas of the northern slopes and plains, the central tablelands, areas of the central west and the southern tablelands. Relative growth remained low in areas of the north west.

More information For more information, contact the NSW Department of Primary Industries on 02 6391 3100 or Local Land Services on 1300 795 299. Additional and more detailed information on seasonal conditions can be found in the NSW Seasonal Conditions Report, available at http://www.dpi.nsw.gov.au/agriculture/emergency/seasonal-conditions/regional-seasonal-conditions-reports.

Acknowledgements Information used in this report was sourced from the Australian Bureau of Meteorology, CSIRO, Queensland Department of Science, Information Technology and Innovation, the US National Oceanic and Atmospheric Administration, the International Research Institute for Climate and Society (Columbia University) and NSW Department of Primary Industries.

Warning Recognising that some of the information in this document is provided by third parties, the State of New South Wales, the author and the publisher take no responsibility for the accuracy, currency, reliability and correctness of any information included in the document provided by third parties.

© State of New South Wales through the Department of Trade and Investment, Regional Infrastructure and Services, 2015. 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 (June 2015). 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 Department of Primary Industries. ISSN 2203-5060 (Online) PUB15/235 Volume 2/Number 5