South Australia - Fast Break

Author: | Issue: 1 | Date: 28 Nov 2018

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You are reading the 8th Fast Break for South Australia

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Volume 1 | Issue 8 | South Australia | Published: 04 Dec 2018

Welcome to our eighth “Fast Break” newsletter for the South Australian grains industry. Our team has been preparing this monthly newsletter for 12 years in Victoria and with GRDC support we are now able to present it for SA. If you like it, please consider passing it on through your networks and subscribing.

The Pacific Ocean surface and undersea temperatures remain in an El Niño state, but little else is interested in making this a fully-fledged event. Trade winds, cloud patterns at the Dateline and pressure patterns around the equator remain at normal levels. This indicates an uncoupled ocean and atmosphere. In this case, local influences on climate are more likely than classical El Niño effects. Models are keen on the temperature of the Pacific to last at El Niño thresholds for the next five months. Historically, when El Niño’s have occurred over summer, the rainfall has been evenly split between wet, average or dry across South Australia. Autumn El Niño conditions would not necessarily be cause for alarm either, as the Pacific would normally be resetting back to neutral sometime around then. It would be good to see a proper coupled El Niño over summer, to disperse some of the heat out of the Pacific Ocean leaving less around for next season.

Summer rainfall predictions are all over the shop, wetter, average and drier. Such a wide mix is not uncommon from the models in summer. Plan for anything, would be the catch cry.

Historically, the most likely effect of a summer El Niño is warmer temperatures and in this most models agree.

map of SA showing dry soil to depth and moisture probes confirming that.
The BoM AWRA modelled plant available soil moisture (10-100cm) shows that all but the Fleurieu, Kangaroo Island and SE are dry to depth. Monitored moisture probes (courtesy of NR-SAMDB, EPARF, SARDI and Agbyte) show that some areas have had storms and increased soil moisture (pink dots). The vast majority of areas have barely changed for the month.
Graphs showing the distribution of December-February modelled rainfall as mixed, with likely warmer temperatures.
Graphs showing the distribution of March-May modelled rainfall as likely to be drier/average, with likely warmer temperatures.

Model consensus forecast for the next six months

Current outlook (27 November)

Previous outlook (30 October)

Dec-Feb outlook

Mar-May outlook

Nov-Jan outlook

Feb-Apr outlook

Pacific Ocean

El Niño (Modoki)

El Niño (Modoki)

El Niño (Modoki)

El Niño (Modoki)

Indian Ocean

Neutral/slightly warmer

Slightly warmer

Neutral

Slightly warmer

Rainfall

Mixed

Slightly drier/average

Average

Average/slightly drier

Temperature

Slightly warmer

Slightly warmer

Slightly warmer/average

Slightly warmer

Equatorial Pacific Ocean Sea surface temperatures have just reached El Niño thresholds. A +IOD continues in the Indian Ocean.
Sea surface temperatures (SST) along the Equatorial Pacific have remained stable over November. NINO3 is at +0.81oC and NINO3.4 is +0.78oC (as of 30 Nov), just at El Niño thresholds (+0.8oC). The warming is currently along classical lines starting from Ecuador. Most models are predicting a Modoki type warming in the NINO 3.4 region. The Indian Ocean remains at a weak Positive IOD, being driven by Kenyan warming rather than Sumatran cooling. The Dipole Mode Index, (DMI) has remained above the threshold of +0.4oC for more than two months and has officially been classified as +IOD event. The Coral Sea is average and a good moisture source to Australia’s North East but has a cooling trend.
Equatorial undersea temperatures in the Pacific remain warm in an El Niño state.
The Pacific Ocean Equatorial sub-surface temperatures have cooled a little in November but remain in an El Niño pattern with warmth to depth.
The SOI value is currently at -0.1.
The SOI value is currently at -0.1. During November, the pressure patterns around the Equator have shown no interest in behaving in an El Niño fashion yet. The ocean and atmosphere remain uncoupled.
The Equatorial Pacific trade winds are normal across most of the region.
The Equatorial Pacific easterly Trade Winds were normal across most of the region during November. The reversed trades near PNG would need to extend to the middle of the Pacific to intensify and develop the El Niño over summer.
Cloud is now normal at the junction of the Equator with the Dateline.
Cloud at the International Dateline (180oW) junction with the Equator is now normal (white colour). An El Niño would be expected to show an abundance of cloud (blue colours) in this region. The +IOD lack of cloud off Sumatra has dissipated but a lack of cloud across the whole of the northern region indicates the wet season is yet to fire up.
the SAM has spent November neutral and then positive.
The Southern Annular Mode (SAM) started November in neutral, but then moved into a moderately strong positive phase. In summer, a +SAM can be beneficial to rainfall in the eastern half of Tasmania. This probably partially explains the wetter NE during November. NOAA predicts the SAM to remain moderately positive for the next fortnight.
the STR of high pressure has move further north than its normal position between Adelaide and Melbourne.
In the past 30 days, the Sub Tropical Ridge of High Pressure’s Position has moved a bit further north than usual. During summer though, its influence over Tasmania’s climate is not as great as in winter. Of greater interest has been the high-pressure positioning in the Tasman Sea and off Western Australia, causing a frequent low-pressure trough region over Tasmania. Therefore, there has been northerly winds, humidity and some thunderstorm rainfall during November.
Pressure at Darwin and Tahiti are similar, while pressure over SE Australia has been lower.
The Sub Tropical Ridge of High Pressure’s Strength was lower over Tasmania during November, allowing some connections to the tropical moisture. Pressure at Darwin and Tahiti are both slightly higher which is why the SOI is neutral.
12 climate models show their predictions for the next six months for the Pacific Ocean, Indian Ocean, rainfall and Temperature for South Australia.
Download this table in word format here

Modelled Climate and Ocean Predictions for South Australia from November 2018 run models

Ocean-Atmosphere Coupled Models

Multi Model Ensembles

Statistical

System 5

ECMWF

Europe

ACCESS-S

BoM

Australia

SINTEX-F

JAMSTEC

Japan

CFSv2

NCEP

USA

GEOS-S2S

NASA

USA

ENS

JMA

Japan

CSM1.1m

BCC

China

UKMO

GloSea5

UK

NMME

USA

APCC

Korea

EUROSIP

Europe

SOI phase

USQ/Qld

Australia

Month of Run

Nov

Nov

Nov

Nov

Nov

Nov

Nov

Nov

Nov

Nov

Nov

Nov

Forecast months

DJF

DJF

DJF

DJF

DJF

DJF

DJF

DJF

DJF

DJF

DJF

DJF

Rainfall Skill

Low/ Moderate

NA

NA

Low/ Moderate WEP

Low/ Moderate

Low

NA

Moderate

Low

NA

NA

NA

Summer Pacific Ocean NINO3.4

Warm

(El Niño)

Warm

(El Niño)

Warm

(El Niño Modoki)

Warm (El Niño Modoki)

Warm

(weak El Niño Modoki)

Warm (El Niño)

Warm

(El Niño

Modoki)

Warm

(El Niño Modoki)

Warm (El Niño Modoki)

Warm (El Niño Modoki)

Warm (El Niño Modoki)

Consistently near neutral

Summer Eastern

Indian Ocean

Neutral

Slightly warm

Slightly warm

Warm

Slightly warm

Neutral

Neutral

Neutral

Neutral

Slightly warm

Slightly warm

-

Summer Rainfall

Slightly drier/average EP

Average/

slightly drier SE

Average

Average

Average

Average/ slightly wetter EP

Average/ slightly wetter EP

Slightly drier

Slightly drier

Average

Slightly drier

Average E/ slightly wetter W

Summer Temperature

Average/ slightly cooler
KI

Average S/ slightly warmer N

Slightly warmer

Average W/ slightly warmer E

Slightly warmer

Average

Average/ slightly cooler SE

Slightly warmer

Slightly warmer

Slightly warmer

Slightly warmer

-

Forecast months

MAM

MAM

MAM

MAM

MAM

-

MAM

FMA

MAM

MAM

FMA

-

Autumn Pacific Ocean NINO3.4

Warm

(El Niño)

Warm

(El Niño)

Warm

(El Niño Modoki)

Warm

(El Niño

Modoki)

Neutral

-

Warm

(El Niño

Modoki)

Warm

(El Niño Modoki)

Warm

(El Niño)

Warm

(weak El Niño Modoki)

Warm (El Niño Modoki)

-

Autumn Eastern

Indian Ocean

Slightly warm

Slightly warm

Slightly warm

Warm

Slightly warm

-

Neutral

Slightly warm

Slightly warm

Slightly warm

Slightly warm

-

Autumn Rainfall

Average/

slightly drier EP, KI

Slightly drier/average E EP

Average/

slightly drier SE

Average

Average

-

Slightly drier

Slightly drier

Average

Average

Slightly drier

-

Autumn Temperature

Slightly warmer

Slightly warmer

Slightly warmer

Average

Slightly warmer

-

Average

Average

Slightly warmer

Slightly warmer

Slightly warmer

-

Notes

Operational

Operational

Experimental

Operational

Experimental

Experimental

Operational

Operational

Experimental

Summary of 4 dynamic models

Experimental

Summary of 8 dynamic models

Experimental

Summary of 5 dynamic models

5 phase system based on previous 2 months SOI

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