CLIMATE DRIVERS UPDATE - INDIAN OCEAN AND THE CORAL SEA. WHAT IS HAVING THE GREATER INFLUENCE?

What is the Indian Ocean doing for the coming weeks? The expected peak in the negative phase of the dipole is anticipated during the coming 4-6 weeks and this is where a larger influence is expected to be experienced across many areas of the nation. But what about the Coral Sea, and the well above average SSTs?


Lets take a look.


Current Rainfall Anomalies - Next 2 Weeks

Showing that first signal of the moisture sweeping out of the tropics and coming through Central Australia and into the southeast and eastern inland. So keep watch over the coming week, because this cycle is likely to repeated multiple times in the coming 6 weeks.

Current Rainfall Anomalies - Next 6 Weeks

Outlined this on the weekend and last week, but this is my official forecast for the coming period, this will be updated tomorrow. You can compare with the data sets below.

Sea Surface Temperature Anomalies

Current observations - Monday 4th of October 2021

Marginally warmer waters in the IOD region off NW WA with some influence expected during the coming weeks. The main influence in moisture projection across the country is actually connected to the Coral Sea with easterly trade winds running over the higher than normal SSTs, allowing for deeper moisture to run through northern parts of the nation and then deviating south and southeast into the eastern inland, via the upper level winds. That said the waters in the Indian Ocean and really, right across the northern tropics are expected to warm further as per the seasonal expectations.

Sea Surface Temperature Anomalies

Forecast Anomalies - Tuesday 19th of October 2021

Note the shades of yellow increasing north of Broome to about 1-1.5C above the north and the rapid warming over the Top End and Gulf of Carpentaria through the Coral Sea, temperatures up to 3C above normal. This will see significant moisture begin to pool over northern areas and the build up/wet season ramping up as well later this month in response to these projected SSTs. Significant moisture will be broadcast across the nation, all we need is lower air pressure. I will also note the upwelling of warmer water along the east coast with anomalies of 3C offshore the South Coast of NSW.

IT IS ALL ABOUT THE RAINFALL PROJECTIONS.


Moisture Watch October 11-18 2021

Note the influence of moisture coming from the warmer waters of the Coral Sea into the northern and central inland and then being drawn into inland troughs over QLD and NSW likely to see more rainfall develop into the month. Note this movement of moisture when reviewing the data below.

This is raw data off the European Model for anomalies of rainfall during the coming weeks.


October 4-11 2021.

Note the limited influence of the moisture over the north on rainfall overall for the coming week, and that is fair, some chance of rainfall developing later this weekend and into the following week with a pressure trough over Central Australia and deep moisture being drawn south.

October 11-18 2021

Note the shades of green starting to appear in response to that rainfall event spoken about in the short and medium term forecasts. The projected rainfall could be more widespread than what is being advertised in the raw data here, however the shifting into the wetter phase commences, hand in hand with the warming waters over the north and northeast.

October 18-25 2021

Note the coverage of rainfall increases across the heart of the nation and expands out from there with lower air pressure developing throughout. Frontal weather likely to be further south allowing moisture to pool and deepen throughout the atmosphere, some areas under quite a saturated atmopshere.

Heading into November.

You can see the coverage of rainfall now peaking in line with the SSTs, noted above, elevating to well above average values, likely peaking throughout the end of this month over the Indian Ocean and throughout the tropics into the Coral Sea.

Seasonal Rainfall IRI/CPC - Rainfall Anomalies - October through December.

The seasonal outlook overall is looking wet, the signal is wet for much of the nation and that has been very robust in most outlooks since June, with the peak occurring from later this month through December. I want to make this point, watch the convective activity over Indonesia and northern Australia in the next fortnight as that will give an indication as to whether this forecast is likely to verify.

Seasonal Rainfall IRI/CPC - Temperature Anomalies - October through December.

Still looking cooler than normal for much of the nation if you take the raw data on face value but you must look at overarching synoptic scale, there will be periods of colder weather and periods of warmer weather, but the cloud cover and more widespread rainfall is likely to lead to the cooler signal across the nation rather than freezing southerly winds.

Tomorrow I will have a look at the La Nina chances and the latest data from the international agencies.