NSW Seasonal Conditions Summary July 2017

Overview

During June, rainfall was below average across 61 per cent of NSW, with rainfall across areas of central, southern and south western NSW being the lowest on record for the month.

Rainfall across most of NSW ranked at less than 60 per cent of normal for the month, with the southern half of inland NSW generally ranking at less than 20 per cent of normal, along with some areas of the north west. Areas of above average rainfall occurred across the north east, northern tablelands, Hunter valley, Sydney basin and the northern slopes and plains. Areas of the north west and far north west received near-average rainfall for the month.

Pasture growth remained limited or declined across most of NSW. Despite the warmer than normal daytime temperatures, a combination of lack of moisture, heavy frosts and grazing pressure restricted pasture growth. Annual and native pastures were the most affected. Levels of growth were maintained across some areas of southern NSW, the south of the central west and areas of the northern slopes and plains where rainfall occurred in late May and late June. Growth improved across areas of the far north east.

Relative to historical records, pasture growth was well below average across most of western NSW, and well below average to extremely low across the northern half of the central west and the central Riverina. It was also well below average across areas of the north west, upper Hunter valley and the tablelands. Growth was slightly above average across areas of the far south, north coast and western Riverina but slightly below average to near-average elsewhere.

Other pasture growth models indicated well below average to extremely low growth across most of the southern half of inland NSW. Growth was also below to well below average growth across areas of the north west. Growth was above average for the north coast, northern tablelands, northern slopes, lower Hunter valley, Sydney basin and across areas of the south coast and northern plains. Growth was mostly near-average elsewhere.

Pasture biomass was relatively unchanged during June, and generally remained quite low across most of NSW with the exception of areas of the central west and far south. Relative to historical records, biomass was generally below average across areas of the north west plains, northern slopes, upper Hunter valley, Sydney basin, central Riverina and northern areas of the central west and central tablelands.

Stock condition remained good, with supplementation necessary to maintain condition or to slow its decline in many areas. In these areas, condition slipped where supplementation or forage crops were not available as a result of limited pasture production.

Rainfall in late June improved crop prospects across the northern slopes (east of the Newell Highway) and eastern areas of the north west plains, but light, patchy falls in most other cropping areas did little to improve conditions. Areas of the central west and north west plains (west of the Newell Highway) remain unsown due to the lack of June rainfall. Follow up rainfall is urgently needed across inland NSW to promote growth of late sown winter crops. Early sown dual purpose crops continue to perform well, but also require follow up rainfall to aid growth and grazing recovery. Yield prospects for mid-late sown crops have been reduced due to late sowing and emergence, patchy germination and poor soil moisture. Some late sown crops in south western NSW have been abandoned and grazed out. Wheat and canola crops sown in late April and early May are handling the dry conditions but will need rainfall soon to maintain current yield potential. Weed control and topdressing have also been hampered by the dry conditions.

During June, topsoil moisture declined across much of southern NSW, the south of the central west and areas of the southern and central tablelands. Topsoil moisture improved across areas of the coast, Sydney basin, Hunter valley, northern tablelands and northern slopes. Rainfall in late June and early July improved topsoil moisture across much of northern NSW, the mid-north to north coast and areas of the far south.

Run off during June was well below average across much of inland NSW, but above average across areas of the north coast, northern tablelands and Sydney basin.

NSW Seasonal Conditions Report – July 2017

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Seasonal outlook

The Bureau of Meteorology’s rainfall outlook for July to September (see the Climatic Outlook Summary below) indicates drier than normal conditions are likely across much of inland NSW. There is a near-equal chance of drier or wetter than normal conditions across areas of the far north west, north west, northern tablelands, lower Hunter valley, Sydney basin and most of the coast.

Daytime temperatures are likely to be warmer than normal. Overnight temperatures are likely to be warmer than normal across most of NSW, with a near-equal chance of cooler or warmer than normal overnight temperatures across the far south west.

During July, drier than normal conditions are likely across most of the eastern half of NSW. For the western Riverina, western and far north western NSW, the far north coast and far south east there is a near-equal chance of drier or wetter than normal conditions. Daytime temperatures are likely to be warmer than normal across most of NSW. There is a near-equal chance of cooler or warmer than normal overnight temperatures across most of NSW. Overnight temperatures are likely to be warmer than normal across most of coastal NSW, the far north and most of the northern tablelands, southern tablelands and south west slopes.

These outlooks have been influenced by the likelihood of higher than normal pressure across southern Australia and a positive Southern Annular Mode, leading to fewer cold fronts and low pressure systems and lower levels of cloud.

The NOAA Climate Forecast System (CFS) rainfall outlook for July to September is near-neutral (that is, a near equal chance of drier or wetter than normal conditions) for NSW. The overall temperature outlook is near-neutral for most of NSW. Warmer than normal conditions are possible for areas of the far north east and areas of the coast.

For July, the CFS rainfall outlook is near-neutral for most of NSW, with drier than normal conditions possible in areas of the south to central coast and Hunter valley. The overall temperature outlook is near-neutral for most of NSW.

A survey of the major global climate models in early July indicated that for the majority of NSW a small majority of models (55 per cent) favoured a drier than normal outlook for July to September period. The remainder of models favoured a generally near-neutral outlook (a near-equal chance of drier or wetter than normal conditions). For temperature, a small majority of models favoured a near-neutral outlook, while the remainder of models favoured warmer than normal conditions.

Of the major multi-model ensembles surveyed, most favoured a drier than normal outlook for July to September and they were equally split between warmer than normal and near-neutral conditions.

Overall NSW outlook -
major climate models

Rainfall Outlook
(number of models)

Temperature Outlook
(number of models)

Period

Generally
wetter

Generally
near-neutral

Generally
drier

Generally
warmer

Generally
near-neutral

Generally
cooler

July – September

0

5

6

5

6

0

August – October

0

4

4

5

3

0

The AussieGRASS pasture growth outlook for July to September suggests that above average pasture growth is possible for areas of the north west, northern slopes and plains, northern tablelands, central to north coast, western Riverina and far south east.

Below average growth is suggested for areas of the far west and the eastern and central Riverina, with near-average growth suggested across the remainder of NSW.

The SOI phase seasonal rainfall outlook that the growth outlook is based upon is near-neutral for most of inland NSW between July to September, with wetter than normal conditions possible for areas of the Sydney basin, Hunter valley and mid-north coast. This was based on a rapidly falling SOI phase during May and June. In comparison, the Bureau of Meteorology’s July to September rainfall outlook suggests drier than normal conditions across much of NSW. If these eventuate, potential growth may be very different from the outlook.

The current growth outlook has a moderate to high past accuracy across eastern and areas of far western NSW, but a low past accuracy for areas of central and north western NSW, the far north west and the central Riverina.

El Niño Southern Oscillation (ENSO)

The Pacific Ocean remains in an ENSO-neutral state, with the outlook from most global climate models suggesting ENSO neutral conditions will continue throughout 2017.

The Bureau of Meteorology’s ENSO outlook status is currently ‘Inactive’. The CPC/IRI also indicate that ENSO neutral conditions are present and are likely to continue into spring. Note that the Bureau and CPC/IRI use different ENSO thresholds.

Some models indicate that a positive or borderline positive Indian Ocean Dipole (IOD) event is possible in late winter to early spring, however any development appears to have temporarily stalled and the Dipole Mode Index remains neutral. Positive IOD events tend to suppress rainfall across Australia during winter and spring.

Sea-surface temperatures across most of the western to eastern-central equatorial Pacific are near-average to slightly warmer than average. Whilst warm, temperatures in the central equatorial Pacific still remain within the neutral (neither El Niño nor La Niña) range. There has been some cooling in areas of the east.

In the sub-surface, areas of weak warm anomalies are present across most of the western, central and eastern-central equatorial Pacific to a depth of about 100m, with a weak cool anomaly below this in the western-central to central Pacific. Weak warm anomalies are present in the west and east at depth.

The easterly trade winds were close to normal throughout June, with some reversal in the far east.

The Southern Oscillation Index (SOI) is currently slightly negative (at El Niño levels), but this is due to high atmospheric pressure over Darwin rather than the result of El Niño atmospheric coupling.

Atmospheric pressure was higher than normal over Australia during June, with slow moving high pressure systems common in the Great Australian Bight. This is due to the subtropical ridge being further south and much stronger than normal for the time of year. This acts to block the passage of fronts and results in warmer than normal daytime temperatures and frosty nights across inland NSW, but increases the likelihood of easterly onshore winds and rainfall along the coast.

The strong and southerly subtropical ridge has also contributed to the westerly winds below Australia moving further south, which is shown by the Southern Annular Mode (SAM) being currently strongly positive. During autumn and winter, this drags cold fronts further south, preventing them passing over southern Australia.

The short term outlook suggests the SAM may return to neutral levels in late July, but the overall outlook suggests high atmospheric pressure will continue across southern Australia into winter, together with a positive SAM.

Under ENSO-neutral conditions, other influences such as the SAM, atmospheric pressure and sea surface temperatures near the continent tend to have a greater effect on the climate.

Climatic outlook summary

NSW Seasonal Outlook (BoM)

Current outlook

Previous outlook

Quarterly Rainfall

Drier

(most of NSW)

Near-neutral

(areas of the coast, north, Hunter valley and northern tablelands)

Drier

(most of NSW)

Near-neutral

(areas of the coast, far south east, north east and the northern tablelands)

Quarterly Maximum Temperature

Warmer

Warmer

Quarterly Minimum Temperature

Warmer

(most of NSW)

Near-neutral

(far south western NSW)

Warmer

(areas of eastern, northern, central and southern NSW)

Near-neutral

(most of western NSW, western Riverina and areas of the central west)

El Niño Southern Oscillation (ENSO)

ENSO (overall)

Neutral

Neutral

BoM ENSO Outlook Status

Inactive

Inactive

Southern Oscillation Index (SOI)

Slightly negative

(as a result of high pressure over Darwin, rather than an El Niño signal)

Neutral

Pacific Ocean (NINO3.4)

Neutral

(warm)

Neutral

(warm)

Indian Ocean (IOD)

Neutral

(western Indian Ocean slightly warm)

Neutral

(eastern Indian Ocean slightly cool)

Southern Annular Mode (SAM/AAO)

Strongly positive

(trending to near neutral, but with a positive outlook throughout winter)

Near neutral

(trending to moderately positive)

Note: Climate model outlooks are updated regularly. To check whether updates are available, use the hyperlinks provided.

Rainfall and temperature

June was the driest since 2002, with many areas in the southern inland having their driest June on record. This contrasted with some areas of far north eastern NSW receiving their wettest June on record.

During June, rainfall was below average across most of central, southern and south western NSW as well as areas of the north west. Rainfall across most of these areas was less than 20-40 per cent of average.

Rainfall across the state ranged from 0.2-438 mm. Across southern, western and central inland NSW, falls were light and patchy. Most of southern and south western NSW, the south of the central west, areas of the north west and the Monaro and the western side of the southern and central tablelands received rainfall of 0-10 mm.

Most of the north west, far north west and the north of the central west received rainfall of 10-25 mm. The upper Hunter valley received 10-50 mm. Rainfall along the south coast, northern tablelands, northern slopes and areas of the northern plains generally ranged from 25-50 mm. The Sydney basin, central coast, lower Hunter valley and north coast had rainfall of generally 50-200 mm or more, with some areas of the mid-north to north coast receiving rainfall in excess of 200 mm.

Daytime temperatures were generally well above average for the month, particularly across areas of the north, north west and areas of central NSW. Daytime temperatures were near average for areas of the coast and Hunter valley.

Overnight temperatures were below average across much of southern, central and western NSW, with frequent frosts. Overnight temperatures were above average across areas of the north west, north east, Hunter valley, Sydney basin and central coast.

Relative rainfall

Rainfall across NSW during June was below average across 61 per cent of the state and average across 30 per cent of the state. Rainfall was above average across 9 per cent of the state, primarily in the north east.

Rainfall was well below average to extremely low (in the lowest 10-20% of years) across most of southern, south western and central NSW, including most of the southern and central tablelands. Rainfall was also below average across areas of the north west.

The far north west and areas of the northern slopes and adjacent plains received near-average rainfall for the month, as did the west of the northern tablelands and most areas of the upper Hunter valley, Illawarra and south coast.

Above average rainfall was limited to eastern areas of the northern tablelands, the north coast and areas of the Sydney basin and central coast. Some areas of the far north east received extremely high relative rainfall (rainfall in the top 10% of years).

Quarterly relative rainfall was below average across 48 per cent of the state and near-average across a further 48 per cent, with above average rainfall restricted to 4 per cent of the state. Below average rainfall occurred across central NSW, areas of the north west and western NSW, the eastern and central Riverina, upper Hunter valley, southern tablelands and southern highlands. Above average rainfall was restricted to areas of the south west, northern tablelands and slopes and the far north east.

Soil moisture

During June, topsoil moisture declined across much of southern NSW, the south of the central west and areas of the southern and central tablelands. Topsoil moisture improved across areas of the coast, Sydney basin, Hunter valley, northern tablelands and northern slopes. Rainfall in late June and early July improved topsoil moisture across much of northern NSW, the mid-north to north coast and areas of the far south.

Relative to historical records, average June topsoil moisture levels were below to well below average across the Riverina, far south, central west, southern and central tablelands and areas of the north west and far west. Above average topsoil moisture was limited to areas of the north coast, northern tablelands, northern slopes and Sydney basin.

The most reliable soil moisture models indicated declines in subsoil moisture during June across most of northern, central and southern NSW. Relative to historical records, subsoil moisture levels were below to well below average in these areas. Increases soil moisture occurred across some areas of the western Riverina, north coast, northern tablelands and northern slopes. In these areas, soil moisture was above average. Other soil moisture models indicated above average soil moisture across much of western, central and southern NSW and the northern tablelands.

Soil moisture levels generally remained low across most of inland NSW into early July.

Streamflow

Run off during June was well below average across most of inland NSW due to limited and patchy rainfall.

Yearly run off to June remained influenced by the wet conditions in 2016 It was above average to extremely high across much of western and southern NSW and across the tablelands, northern slopes and north coast. Run off was below average across areas of the north west, the northern central west and the far south coast.

The Bureau of Meteorology's streamflow forecast indicates near-median streamflows are likely at most NSW monitoring stations during June to August. Low to near-median streamflows are almost equally likely at some far southern locations.

Relative pasture growth and biomass

Relative to historical records, AussieGRASS modelled pasture growth during June was below average across most of western NSW, the upper Hunter valley, the north of the central west, the central Riverina and areas of the north west and the tablelands. It was near-average in other areas and above average in limited areas of the far north east and far south.

Other pasture growth models indicated well below average to extremely low growth across most of southern NSW, the south of the central west and far west, the central and southern tablelands and the Monaro. Growth was also low across areas of the north west. Growth was above average across the northern slopes, northern tablelands, north coast, lower Hunter valley and Sydney basin. Growth across the remainder of NSW was generally near-average.

Over the quarter, AussieGRASS relative growth remained below average across areas of the far west, north west, northern central west, central Riverina, northern slopes, northern tablelands and upper Hunter valley. Growth was above average across areas of the far south, south east, coast, and the south of both the central west and central tablelands.

During June, relative biomass levels were below average across areas of the north west plains, northern slopes, upper Hunter valley, Sydney basin, central Riverina and northern areas of the central west and central tablelands. Levels were above average across limited areas of the far south east, far south, far west and the south of the central west.


Figure 1: Relative monthly topsoil moisture

Small map of relative soil moisture (upper level) - average value for June 2017

Figure 2: Relative quarterly pasture growth

Small map of pasture growth relative to historical records from 1957 - April 2017 to June 2017

More information

For more information, contact the NSW Department of Primary Industries on 02 6391 3100 or Local Land Services on 1300 795 299.

Acknowledgements

Information used in this report was sourced from the Australian Bureau of Meteorology, CSIRO, the Queensland Department of Science, Information Technology and Innovation, the Queensland Alliance for Agriculture and Food Innovation, the U.S. Department of Agriculture, U.S. Department of Commerce, the U.S. National Oceanic and Atmospheric Administration, the International Research Institute for Climate and Society (Columbia University), the UK Meteorological Office, the APEC Climate Centre, NSW Local Land Services and NSW Department of Primary Industries.

External links

Disclaimer

The seasonal outlooks presented in this report are obtained from the Australian Bureau of Meteorology and 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 and decision making. Changes in seasonal outlooks may have occurred since this report was released. Outlook information was up to date as at early July 2017.

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.

The information contained in this publication is based on knowledge and understanding at the time of writing (7 July 2017). 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, Local Land Services or the user’s independent adviser.