This is to supplement the detailed climate information that has been posted this week. So lets get straight to it.

Southern Annular Mode - Trending Negative

This is now being reflected in the fast flow pattern on the short and medium term modelling. The SAM in a negative phase leads to the westerly wind belt surging north and more frontal weather developing for the nation. We will see this happen next week as the mode peaks negative by this time next week, before trending back towards neutral and some chance of a positive phase developing at the end of the first week of August which leads us to the pattern flip discussed earlier.

SAM Forecast for the coming 2 weeks. There are signals for that pattern flip at the end of the first week of August and judging by the signals from the members forecasting this volatile climate driver, that is probably the right call. But will have more on that Tuesday with the next monthly outlook.

Indian Ocean - Negative

Clearly this has not changed and will not change for the coming 4-6 months so the wet signal will continue. That makes forecasting relatively simple for this driver, the complexity comes with each impulse of moisture and how that is utilised and whether it is in phase with a negative or positive SAM.

BoM Forecast - now in line with other global agencies. The deeper the event, the longer it takes to return to normal values.

ENSO - Neutral

The ENSO is in cool neutral and will likely remain that way even though there is a 60% chance of a La Nina developing in the spring. I still stand by the cool neutral for summer time, however, if the La Nina does develop and overlaps with the negative IOD, well then rainfall forecasts are under doing the amount of rainfall that is possible in the spring and summer, so we have to look at this data frequently in the coming 6 weeks.

So where we stand for the coming periods.

Rainfall and Temperature Outlook for the coming 2 weeks.

Rainfall largely will follow the same pattern for the coming fortnight in line with the drivers in place, particularly the negative SAM phase that is anticipated for the coming 7 days. But a pattern flip may develop into early August.

Rainfall Outlook for August

The rainfall starts to pick up in the second half of the month for the eastern inland, some spotty out of season showers for the north also possible for the second half of August over the NT and QLD. But the wet signal does remain for the southern and eastern areas of the nation with the moisture continuing to be utilised with frontal weather. The cooler signal starting to decrease over the southern parts too. However the above average temperatures may begin to seep south.

Rainfall Outlook for August to October.

Note the rainfall does certainly increase dramatically as the nation warms up and we see the retreating of the fast flow pattern. Inland troughs also helping to lift the moisture into useful areas of rain for thirsty parts of NSW, QLD and SA. The wet season will kick off early this year with an early build likely. That will reduce the heat levels for the north, but still above average. Pockets of the inland of NSW and QLD may be cooler than normal with persistent rainfall.

I will have another major climate update on Tuesday.

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