CLIMATE DRIVERS UPDATE - EARLY JULY LOOK AND IMPACTS.

INDIAN OCEAN DIPOLE

The Indian Ocean is forecast to turn negative throughout the coming 2-4 months, with the persistent warming of the basin. You can see the classic appearance of the Indian Ocean being in a negative phase with the tight thermal gradient bunched up over the Indonesian Archipelago northwest and west of Australia. While the impacts of this warmer water have not been observed in full flight just yet, the overwhelming signal from the models is that a very wet late Winter into a very wet Spring and possibly early Summer is still on the cards for large areas of the nation (see below). Temperatures are forecast to warm over the northwest and north of the nation through the latter parts of Winter and into Spring, but a cooler Spring is forecast for the remainder of Spring into early Summer 2022. The overwhelming trend is for the Indian Ocean Negative Dipole to create a problematic harvest period for the south and east of the nation. WA should see above average rainfall via elevated SSTs sitting off the west and southwest coast through Spring. Early onset rainfall and early build up conditions are forecast for the northern tropics as well.

ENSO REGION

The ENSO region is returning to neutral impacts across the Pacific Ocean as the subsurface warms and the trade winds weaken and this allowing the waters to mix out from the colder signals over parts of the central and eastern basin. You may note the warmer bias over the Coral Sea has also come down in recent weeks which is seasonally expected but the warmer waters from the past La Nina is still trapped over northern Australia and combining with the warmer waters spreading in from the developing IOD. Overall the ENSO is forecast to remain neutral into Spring (59%) and Summer could see a La Nina redevelop (64%) which would once again send the nation into a cooler and wetter season for the third year in a row with higher humidity. This forecast confidence is expected to improve in this region over the coming 6-8 weeks.

SOUTHERN ANNULAR MODE

The SAM is forecast to remain rather neutral overall throughout the coming period with a tendency for there to be weaker positive and negative phases over the coming 2-3 weeks leading to that suppressed rainfall signal across the nation with high pressure dominating the continent. There may be some more active SAM phases coming into August with a tilt towards a negative phase growing in mid-August (65%) and again at the end of August (58%) which may assist in drawing in more moisture throughout much of the nation via the jet stream sitting through the warmer waters of the Indian Ocean.

SEA SURFACE TEMPERATURE FORECAST JULY

Noting the waters over the ENSO region are starting to ease from the secondary cooler evolution through April and May. Conditions should remain cool neutral through July. Waters over northern Australia and extending into the east and through western parts of the nation are forecast to continue for the next month and strengthen further, particularly the Indian Ocean. The waters over southern and eastern Australia, mixed which is normal for this time of year and should remain so.

SEA SURFACE TEMPERATURE FORECAST AUGUST

The waters offshore Indonesia through to northern Australia strengthen to be 2-3C above normal and warming further through August. The ENSO region continues to hold at cool neutral with the region expected to have little impact on the nation. Though the damming of the warmer waters through the Coral Sea extending through the north and back into the Indian Ocean will result in significant moisture and rainfall over northern Australia and this feeding southwards into the eastern and central parts of the country, setting up a wet end to August and a wet Spring.

RAINFALL OUTLOOK - REMAINDER OF WINTER 2022

TEMPERATURE OUTLOOK - REMAINDER OF WINTER.

More to come on this in a fortnight and a look at Spring 2022 later this week.




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