The Fast Break Newsletter 12 February 2020Seasonal climate risk information for Southern NSW

Volume 2 | Issue 1 |12 February 2020

Welcome to the “Fast Break” newsletter for the Southern New South Wales grains industry. We have been constructing these summaries for the last 11 years in Victoria, and started last year in South Australia, New South Wales and Tasmania as part of the GRDC funded “Using Seasonal Forecasts Project” project. If you like it, please consider passing it on through your networks and subscribing.

We are describing SNSW as a line south of Dubbo. In the predictions, I divide this region into quarters, hence N, S, E, W, NW, NE, SW, SE, defines zones in this southern half. If the models are more precise, I might use terms such as coast, Riverina, central west, etc.

The +IOD and the -SAM that conspired to give eastern Australia very dry and hot weather in December both died around new year. The northern wet season which had been inhibited by these drivers at that time was then able to kick off. Since then, summer weather has been a bit erratic.At the moment, both the El Nino Southern Oscillation and the Indian Ocean Dipole are in neutral phases as is normal for now. We reach the dodgy time of the year where random things can happen to push them in a direction for winter, with limited predictability. Ocean temperatures to our north are generally much warmer, which instigates greater evaporation. Models agree that the Indian and Pacific Oceans are likely to stay warmer for the next three months to the north of Australia.We currently have enhanced cloud formation over the Coral Sea to the north-east of Australia. This is providing a good moisture source but only if the right triggers drift past. Decreased cloud to our north and increased pressure, are a hang-over from mid-January, where more recent measurements of cloud at least, are closer to normal. The higher pressure north of Darwin is normally not a good omen for moisture transport and probably not helping the western regions.The Southern Annular Mode is now behaving itself, bouncing around from weakly positive to weakly negative. This would be expected to have little influence on NSW’s climate.Pressure has been lower due to the positioning of large stable highs to our west and east. If this pattern continues, we could expect some more humid and unstable weather.For the next three months models are firmly sitting on the fence for any outcome is possible, drier, average or wetter, but there are sniffs of drier from a few. There is a strong consensus for warmer temperatures.

Do you want to hear the latest science, insights and innovations happening in the climate and agriculture space?  Then the 2020 Climate Webinar series is where you will hear from the experts from Agriculture Victoria, BoM, CSIRO and other agencies.  The series will run during lunchtime or you also have the option to listen to recordings at a time that suits.  For more information and to subscribe to keep up-to-date with these upcoming climate webinars visit:   http://agriculture.vic.gov.au/agriculture/weather-and-climate/climate-webinarsor email heather.field@agriculture.vic.gov.au

Soil Moisture

File - soil moisture SNSW.pngAlt text - map of Southern NSW showing plant available moisture (%).Caption – The BoM Australian Water Resources Assessment (AWRA) modelled soil moisture shows the Riverina has not enjoyed the rainfall that areas further north have received. The Central West has had the best recent falls of up to 100mm and increasing stored moisture. That region is currently rated very much above average.

Model distribution summary for the next three months

File - 1-3 month SNSW.pngAlt text - Graphs showing the distribution of global model forecasts for February-April, with models split between average or drier and a stronger consensus for warmer.

Model distribution summary for the next four to six months

File - 4-6 month SNSW.png

Alt text - Graphs showing the distribution of May-July forecasts with models showing equal chances of wetter, average or drier and a stronger consensus for warmer temperatures.

Model consensus forecast for the next six months

Current outlook (to 11 February) Previous outlook (to 28 November)Feb-Apr May-Jul Dec-Feb Mar-May

Pacific Ocean Slightly warm Slightly warmer/ slightly cooler

Neutral/warmer Neutral

Indian Ocean Slightly warm Slightly warm Cold (+IOD) Warmer

Rainfall Average/slightly drier Slightly warmer Slightly drier Average/

slightly drierTemperature Average Slightly warmer Slightly warmer Slightly warmer

Sea Surface Temperature Anomalies

File - SSTa.pngAlt text - Equatorial Pacific Ocean Sea surface temperatures and the IOD are at neutral levels.Caption The +IOD finally broke down in the first week of January which was historically very late. Current values of the Dipole Mode Index are -0.06oC (as of 11 February) which are totally neutral. This is to be expected for this time of the year. Sea surface temperature (SST) anomalies along the Equatorial Pacific have slightly cooled over summer to remain at neutral temperatures. NINO3 is at +0.11 oC and NINO3.4 is +0.24oC (as of 11 February). The Coral, Arafura and Timor Seas to our north are warmer than normal and evaporating more moisture. If the right trigger can be received summer rainfall is possible.Equatorial Pacific Sub-Sea Temperature Anomalies

File - Deep sea a.pngAlt text - Equatorial undersea temperature anomalies in the Pacific have shown little change for some months.Caption - The Pacific Ocean Equatorial sub-surface temperatures anomalies have changed little over the last three months. A warm patch exists below the western Pacific, which could be vulnerable to reversed trade winds pushing it under and over to South America.Southern Oscillation Index

File - SOI.png

Alt text - The SOI value is currently at +0.1 (as at 11 February).The SOI has been in neutral territory for the last three months. The value is currently neutral at +0.1 (as at 11 February). In summer, the SOI is a less reliable indicator, due to large swings in local pressure at Darwin and Tahiti when cyclones occur.Pacific Ocean Surface Wind Anomalies

File - trade winds.pngAlt text - The Equatorial trade wind are reversed off PNG but are stronger in the Central Pacific.Caption - The Equatorial Pacific Easterly Trade Winds have shown stronger easterly behaviour in the Central Pacific. Paradoxically there is some reversal to westerly off Papua New Guinea. The convergence of these two is causing greater cloud formation.World Cloudiness Anomalies

File - OLR.jpgAlt text - Cloud is abundant over the Dateline and lacking to the north of Australia.Caption - Cloud at the International Dateline (180oW) junction with the Equator is much greater (blue colour) which is suggestive of El Niño, but the projection of greater cloud further west into the Coral Sea is not in keeping with El Niño. The lack of cloud (brown colour) over Indonesia still shows some hang over from the +IOD pattern of last year. Greater cloud over eastern Australia has been from moisture streaming in from the warm Coral SeaSouthern Annular Mode

File- SAM.pngAlt text- the SAM had spent most of November in strong negativity.The Southern Annular Mode (SAM) or Antarctic Oscillation (AAO) was negative into December but has remained close to normal during January and into February. In summer a negative SAM would classically cause drying along the eastern half of NSW. The finger can be pointed at SAM for aiding the dry spring and early summer. NOAA predicts that for the next 14 days the SAM will have a small negative burst. Once we reach autumn SAM has a variable effect on our climate.Air Pressure

File - STR posn.pngAlt text - the STR of high pressure has been slightly higher than its normal summer position of Melbourne.Caption - In the past 30 days, the Sub Tropical Ridge of High Pressure (STR) has been slightly north of the normal summer position of Melbourne. This has been inhibiting the tropical air from getting to the western regions. We have been situated between two high pressure systems which has been moderating the extremes of climate. There has been more troughing of moisture from the north.Air Pressure Anomalies

File - STR strength.pngAlt text - Pressure at Darwin and Tahiti is slightly higher which is why the SOI is neutral. Victoria has seen lower than average pressure.Caption - The Sub Tropical Ridge of High Pressure has been lower over SE Australia, indicating more opportunity for rainfall and unstable weather. The position of low pressure put the western region in the drier zone. Pressure at Darwin and Tahiti is slightly higher which is why the SOI is neutral. Slightly higher pressure to our tropical north is linked to the lack of cloud in that region too.

Modelled Climate and Ocean Predictions for Southern NSW from January 2020 run models

Ocean-Atmosphere Coupled Models Multi Model Ensembles Statistical

System 5ECMWFEurope

ACCESS-SBoM

Australia

SINTEX-FJAMSTEC

Japan

CFSv2NCEPUSA

GEOS-S2SNASAUSA

EPSJMA

Japan

CSM1.1mBCCChina

GloSea5UKMO

UK

NMMEUSA

C3SEurope

MMEAPCCKorea

SOI phaseUSQ/QldAustralia

Month of Run Jan Jan Jan Jan Jan Jan Jan Jan Jan Jan Jan Jan

Forecast months FMA FMA MAM FMA FMA FMA FMA FMA FMA FMA FMA FMA

Rainfall Skill FMA Low E/Moderate W Moderate - Low Moderate Low - Moderate Low W/

Moderate E - - -

Autumn Pacific Ocean NINO3.4 Slightly warm Slightly warm Slightly warm Slightly warm Slightly cool Neutral Slightly warm Slightly warm Neutral Slightly warm Slightly warm SOI rising

Autumn EasternIndian Ocean Slightly warm Warm Slightly warm Warm Slightly warm Slightly warm Slightly warm Slightly warm Slightly warm Slightly warm Slightly warm -

Autumn Rainfall Average Average Slightly drier Average Average Slightly drier Average E, slightly drier W

Average central,

slightly drier E & W

Average Average Average Slightly drier

Autumn Temperature AverageWarmer E,

slightly warmer W

Slightly warmer, average SW

Slightly warmer, average SW Average Slightly

warmerAverage,

slightly warmer SE

Slightly warmer

Slightly warmer,

average SWSlightly warmer Slightly warmer -

Forecast months MJJ MJJ JJA MJJ MJJ - MJJ AMJ MJJ AMJ MJJ -Winter Pacific Ocean NINO3.4 Slightly warm Slightly warm Slightly warm Slightly cool Slightly cool - Slightly cool Slightly warm Slightly cool Slightly warm Slightly warm -

Winter EasternIndian Ocean Slightly warm Slightly warm Neutral

(weak +IOD) Slightly warm Slightly warm - Neutral Slightly warm Slightly warm Slightly warm Neutral -

Winter Rainfall Slightly wetter - Slightly drier, average ranges

Average N, slightly wetter S Average - Average W,

slightly drier E AverageSlightly wetter

Average SWAverage Average -

Winter TemperatureSlightly

warmer E, average W

- AverageAverage,

slightly warmer ranges, coast

Slightly warmer, average ranges

- Slightly warmer Slightly warmer

Slightly warmer

Slightly warmer Slightly warmer -

Notes Operational Operational Experimental Operational Experimental Experimental Operational OperationalExperimentalSummary of 4

dynamic models

ExperimentalSummary of 6

dynamic models

ExperimentalSummary of 8 dynamic

models

5 phase system based on previous 2

months SOI

File- big table SNSW.jpgAlt text- 12 climate models show their predictions for the next six months for the Pacific Ocean, Indian Ocean, rainfall and temperature for SNSW