NSW Seasonal Conditions Summary March 2017

Overview

During February, rainfall was below average across nearly 70 per cent of NSW. It was the third-warmest February on record, with daytime temperatures well above average, particularly during the first half of the month.

Pasture growth was low across most of NSW during February, due to well above average temperatures, high evaporation and low rainfall.

Relative to historical records, pasture growth was well below average across much of inland and far north eastern NSW. Apart from the far north coast, most coastal areas had slightly below average to near-average growth.

Other pasture growth models indicated extremely low growth across most of NSW.

Pasture biomass continued to decline, particularly across the eastern half of NSW. Relative to historical records, biomass generally remained above average across inland NSW, but was below average across most of the tablelands and coast.

Stock condition remained generally good during February. Supplementary feeding has commenced in some areas due to reduced pasture growth and biomass.

High temperatures during January and February damaged and reduced the yield potential of dryland summer crops, particularly in northern, north eastern and central NSW. Irrigated crops have suffered less damage, although additional irrigation was required. Average to above average yields are expected for irrigated cotton. However, due to the conditions some damage has occurred and irrigated cotton yields are likely to be lower than last year. The yield potential for irrigated crops in southern NSW remains average to above average, particularly for rice.

Topsoil moisture levels declined across NSW during February, as a result of the limited rainfall and extremely high daytime temperatures. Topsoil moisture was below average across northern and central NSW, the Hunter valley and the mid-north to north coast. Rainfall at the end of February improved topsoil moisture slightly across areas of the coast north from the Illawarra. Subsoil moisture also declined, although it remained above average across most of inland NSW. However, it was below average across areas of the coast.

Run off during February was below average across most of NSW.

NSW Seasonal Conditions Report – March 2017

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Seasonal outlook

The Bureau of Meteorology’s rainfall outlook for March to May (see the Climatic Outlook Summary below) indicates drier than normal conditions are likely across most of NSW, with a near-equal chance of drier or wetter than normal conditions across areas of the coast. Daytime and overnight temperatures are likely to be warmer than normal.

During March, drier than normal conditions are likely across most of NSW, with a near-equal chance of drier or wetter than normal conditions for areas of the coast, Sydney basin, lower Hunter valley and the north coast. Daytime and overnight temperatures are likely to be warmer than normal.

The NOAA Climate Forecast System (CFS) rainfall outlook for March to May is near-neutral for most of eastern NSW. Below average rainfall is possible for western NSW as well as areas of southern NSW and the central west. The overall temperature outlook is for warmer than normal conditions across most of NSW, with a near-neutral outlook for the south.

For March, the CFS rainfall outlook is near-neutral for most of NSW. The overall temperature outlook suggests warmer than normal conditions are likely across the northern half of NSW, with a near-neutral outlook for the south.

A survey of the major global circulation models in early March indicated that most (60 per cent) favoured a generally near-neutral rainfall outlook (that is, a near-equal chance of drier or wetter than normal conditions) for March to May. One model favoured a generally wetter outlook and five a generally drier outlook. The Bureau’s seasonal outlook for the period was included in the latter. For temperature, most models (79 per cent) favoured a warmer than normal outlook, with three favouring a generally near-neutral outlook. It should be noted that model accuracy tends to be low in late summer to autumn, particularly for outlooks spanning the winter.

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
March – May 1 9 5 11 3 0
April – June 1 4 5 7 2 1

The AussieGRASS pasture growth outlook for March to May suggests that below average pasture growth is possible across most areas of inland NSW. Above average growth is suggested for areas of the coast, the east of the tablelands and the south west slopes.

The seasonal rainfall prediction that the growth outlook is based upon is for near-equal chance of drier or wetter than normal conditions for most of NSW between March and May. This was based on a near zero SOI phase during January and February. In comparison, the Bureau of Meteorology’s March to May rainfall outlook suggests drier than normal conditions across most of NSW.

The current growth outlook has a very low past accuracy across most of NSW, and accuracy is likely to remain low throughout autumn.

El Niño Southern Oscillation (ENSO)

The Pacific Ocean remains in an ENSO-neutral state. Most models suggest neutral conditions continuing throughout autumn, with gradual warming of sea surface temperatures in the central equatorial Pacific. A number of models suggest warming to El Niño levels by winter, given the current sea surface temperatures in the far western and far eastern equatorial Pacific, the rate of warming and the slowly falling SOI. However, model skill tends to be low until early winter.

Sea surface temperatures during February were near-average to slightly below average across the central and eastern-central equatorial Pacific. Temperatures have been warming and were above average across the eastern equatorial Pacific, and the warmer temperatures have expanded westwards since early January. Temperatures were also above average in the western equatorial Pacific. Temperatures in the equatorial Indian Ocean were near-average to slightly below average. Temperatures to the north of Australia were slightly above average, and above average along the east coast.

During February, cloud levels remained low near the junction of the equator and the International Date Line and to its east and west. Cloud levels were high over Indonesia and the Philippines, but were normal to below normal across much of eastern Australia.

The cool subsurface temperature anomaly extending across the central and eastern equatorial Pacific has weakened since last year, but strengthened slightly in early February and began to weaken again in early March. Weak warm anomalies are present in areas of the west and below 200m in the central equatorial Pacific.

The easterly Pacific trade winds were near average over the month over the central Pacific, with a reversal in the eastern Pacific and some strengthening in the west.

The SOI remained neutral during the month, but has been slowly falling since January. This can be an indicator of a developing El Niño event.

The Bureau of Meteorology’s ENSO outlook status shifted from inactive to El Niño watch in late February. This indicates an increased chance (50 per cent) of El Niño conditions developing, although ENSO neutral conditions are currently still present.  The CPC/IRI currently indicate that ENSO neutral conditions are present and are likely to continue throughout autumn. However, they suggest there is an increasing chance for El Niño development into spring. Note that the Bureau and CPC/IRI use different ENSO thresholds.

With no major influence from the Pacific and Indian Oceans, secondary climate drivers tend to have more influence over conditions.

The sub-tropical ridge is in a near-normal summer-early autumn position, and when in this position tends to suppress cold front activity. Higher than average atmospheric pressure is likely over western and southern Australia, potentially leading to fewer rain-bearing systems crossing the coast.

The Southern Annular Mode (SAM) was near-neutral during February, became strongly negative again in early March but has since returned to near-neutral. The current outlook is for it to be near-neutral to weakly positive into late March. In summer, a negative SAM can lead to drier conditions due to blocking moisture flow from the tropics. However, in autumn and winter, a negative SAM can potentially favour increased rainfall.

Climatic outlook summary

NSW Seasonal Outlook (BoM) Current outlook Previous outlook
Quarterly Rainfall Drier (most of NSW)
Near neutral (areas of the coast)
Drier (most of NSW)
Near neutral (areas of the coast)
Quarterly Maximum Temperature Warmer Warmer
Quarterly Minimum Temperature Warmer Warmer
El Niño Southern Oscillation (ENSO)
ENSO (overall) Neutral Neutral
BoM ENSO Outlook Status El Niño watch Neutral
SOI Neutral (slowly falling) Neutral
Pacific Ocean (NINO3.4) Neutral (slowly warming) Neutral (warming)
Indian Ocean (IOD) Neutral Neutral
Southern Annular Mode (SAM/AAO) Near-neutral (tending to remain near-neutral to weakly positive) Near-neutral (tending to remain near-neutral to weakly negative)

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

Rainfall and temperature

Rainfall was less than 60 per cent of average across most of NSW during February. Rainfall in the far west and areas of the central west, central tablelands, north west, western Riverina and upper Hunter valley was less than 20 per cent of average. Many areas received their driest February on record.

Rainfall across the state ranged from 0-457 mm, with most of NSW receiving less than 25 mm for the month. The higher falls were as a result of severe thunderstorms. Much of the west and central west of NSW received less than 10 mm, with many areas of the far west receiving no rainfall. The eastern areas of the state and the tablelands generally received 25 mm or more, except for areas of the central tablelands and upper Hunter valley.

Daytime temperatures during February were the warmest since 1926, with the month being the third-warmest on record for average maximum temperatures. A large number of sites recorded their warmest maximum February temperatures on record between 10-12 February. Temperatures were closer to normal during the second half of the month.

Relative rainfall

Rainfall across NSW during February was below average across 68 per cent of the state and near average across 30 per cent.

Most of the far west, north west, central west and central tablelands received below-average rainfall for the period, as well as areas of the upper Hunter valley, north coast, southern and northern tablelands, Monaro and western Riverina.

Most of the coast, Riverina, northern tablelands and the far south received somewhat below average to near-average rainfall for the month. Rainfall totals for these areas were less than 60-80 per cent of normal.

Above average rainfall was limited to areas of the Sydney basin and Illawarra, and isolated areas of the southern and northern tablelands.

Quarterly relative rainfall was average across 49 per cent of the state, below average across 43 per cent and above average across 8 per cent. Below average rainfall occurred across most of the north west, central west, north coast, Hunter valley, central tablelands, Monaro and the south coast. Other areas of below average rainfall occurred in the far south west and the east of the northern tablelands.

Soil moisture

Topsoil moisture declined across NSW during February, as a result of the limited rainfall and extremely high daytime temperatures. Rainfall at the end of February improved topsoil moisture slightly across areas of the coast north from the Illawarra. Across most of inland NSW, topsoil moisture was between 10 to 20 per cent of a saturated profile and generally less than 30 per cent along the coast.

Relative to historical records, February topsoil moisture levels were below average across the north coast, Hunter valley, central tablelands, much of the central west and areas of the north west, western Riverina and far west. In many of these areas, topsoil moisture was extremely low (in the lowest 10 per cent of years). Levels were generally near-average elsewhere. By the end of the month, below-average topsoil moisture extended across most of western and central NSW and the western Riverina, as well as areas of the Hunter valley, northern tablelands and north coast.

Subsoil moisture levels declined in most areas. Relative to historical records, levels remained extremely high across much of inland NSW. Levels were average across areas of the north west, the eastern areas of the tablelands, south east slopes and areas of the south coast. Subsoil moisture was below average from the Illawarra through to the lower north coast.

Streamflow

Run off during February was below average across most of NSW.

Yearly run off to February remained influenced by the wet winter of 2016. Yearly run off was above average to extremely high across much of NSW, with the exception of areas of the north west, Liverpool Plains, the Hunter valley, Sydney basin and the mid-north to north coast. In these areas, run off was below average.

The Bureau of Meteorology's streamflow forecast indicates low streamflows are likely in most eastern NSW locations during March to Mary, with near-median to high streamflows likely across most inland monitoring stations.

Relative pasture growth and biomass

Relative to historical records, AussieGRASS modelled pasture growth during February was well below average across much of inland and far north eastern NSW. Apart from the far north coast, most coastal areas had slightly below average to near-average growth.

Other pasture growth models indicated extremely low relative growth across most of NSW.

Over the quarter, AussieGRASS relative growth was below average across 50 per cent of NSW, extending across most of northern NSW, the tablelands, upper Hunter valley, south coast, the central west and the south west. Areas of the north and central coast were also below average. The remainder of the state had near-average growth.

During February, relative biomass levels generally remained above average across much of inland NSW. Most of the tablelands, coast and areas of the slopes had below average biomass.

Figure 1: Relative monthly topsoil moisture

Map showing soil moisture results for March 2017

Figure 2: Relative quarterly pasture growth

Map showing pasture growth for March 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 13 March 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 (13 March 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.