Seasonal Update for Autumn Dale Grey Seasonal Risk Agronomist Bendigo

Coupled global circulation models Ocean model + atmosphere model

Anomaly Map

When do the major climate drivers have skill

Does winning the pre season comp in Feb tell you anything about finals contention? In June-July, greater confidence that your team is going OK, or not. Come September its almost assured.

……….strong reversal! And again Ecuador PNG

Central reversal El Niño switch off mechanism. Loss of heat to depth Confused Ecuador PNG

Ecuador PNG Potential 2016 La Niña Plenty of random weather to happen in the tropics before it might happen, if at all.

Currently the Nino 3 and 3.4 areas of the Pacific are slowly cooling at +1.39C, o C, above El Niño thresholds of 0.8 o C, but at this time of the year it’s a case of big deal! 31 st March 2016

The DMI measurement of the Indian Ocean Dipole is neutral, at this time of the year rarely doing much. 31 st March 2016

Timor, Coral and Arafura Seas still warmer, that’s good as a moisture source. Whole Indian Ocean warmest on record, record evaporation going somewhere.

In the last 30 days Cloud at the International Date Line was abundant = El Niño. Lack of cloud to the north of Australia, affecting the northern wet season. But slowly improving. Heaps of cloud over SA, Indian Ocean connection starting to pick up again slowly. cloudyclear

Southern Oscillation Index = SOI = difference in air pressure (Tahiti – Darwin) The SOI has ants in its pants -4.7 and rising. The pattern of high and low pressure around the Equator indicates a neutral status. Slightly higher pressure at both Darwin and Tahiti = neutral. But not worth watching at this time of the year.

Last 30 days Air Pressure H Source = NOAA The Sub Tropical Ridge latitude is in a Summer position, but should be heading north through Autumn. The trough line was in the Tasman Sea.

Last 30 days Air Pressure Anomaly Pressure has been lower over SA. Was a wetter March Darwin pressure higher, Tahiti higher = SOI neutral Be good if pressure returned to normal over northern Australia Source = NOAA

Lameroo

Kadina

Minnipa

Autumn Pacific Ocean-Mixed probably slightly warmer Indian Ocean-Warm Rainfall-Average/slightly wetter Temperature-Slightly warmer

Winter Pacific Ocean-Mixed, probably slightly cooler Indian Ocean-Slightly warm/warm, possible -IOD Rainfall-Slightly wetter Temperature-Mixed

Historically after an El Nino 40% La Nina, 48% Neutral, 12% El Nino Historically, GSR after an El Nino, 75% averagish or better No insight as to the timing of the break, anywhere from Apr–June now. Many models saw a change in pattern towards more rainfall in April, but this is now drifting into May.

History says chances of reasonable rain are good. Models say warm Indian Ocean for some time. Models are supportive of some optimism but at a time of poor skill. La Nina’s of late haven’t fired for spring. Springs are warmer. Pressure pattern in autumn and winter have been causing issues most years, a greater issue in the east of SA

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