We are starting to see the rainfall pattern shifting to the cooler season distribution with early evidence of what is to come relating to the Indian Ocean, with moisture streaming through the jet stream, having a large influence on the above average rainfall distribution throughout the west and over in the east.
The system over QLD in the short term is also feeding off the moisture running through the jet stream from the Indian Ocean. It is merging with moisture via the easterly wind regime as well leading to above average moisture content across the country. So, the pattern looks to continue, when and where it rains, it rains relatively easily and efficiently.
Let's take a look as to whether we see the southern parts of the nation starting to pick on some of those heavier rainfall totals that are being expressed in the longer-term models and we see a reduction in the rainfall totals over the east where flooding is expected to linger for some weeks.
No need for a video today as the guidance has only shifted slightly from Tuesday, so next Climate Rundown coming on Tuesday the 24th of May.
%Chance of exceeding or not exceeding the median rainfall through the coming 6 weeks taking us through to the 4th of July 2022
Rainfall bias for being above average through WA is quite high, running through the jet stream, we can see that in the short term with a few rain bands likely to feature in the next 2 weeks and this will continue to feature through June and into July. With the Indian Ocean tending negative, it is quite likely that we will see more enhanced cloud bands sweeping the nation but bringing further above average rainfall chances throughout the west. The position of each of these bands determines the spread of the above average rainfall chances. Over the SWLD, the weather is forecast to be somewhat wetter than normal with more frequent frontal weather passing through during this period with the long wave trough likely to peak through the region.
The above average rainfall is more likely further south through WA with a higher moisture content the whole region is leaning towards the chance of above average rainfall more likely as an outcome than below average rainfall at this time. The wetter weather could be enhanced by northern cloud bands that develop as we move into July. But overall, the dry season is forecast to be interrupted for northern areas with higher moisture levels thanks to the elevated SSTs in the Indian Ocean and surrounding northern Australia.
Northeastern Australia and Central Australia
With the moisture running through the nation from east to west via the jet stream (which we are seeing today) this will lead to inland rainfall events featuring more than normal and seeding troughs over in the east with the chance of inland rainfall throughout the dry season. The northern tropics are forecast to be more humid than normal with showers and thunderstorms lingering throughout the coming 4 weeks, but conditions may ease into the end of June. The central parts of the nation leaning towards an above average rainfall chance through the coming 6 weeks and is conditional upon the Indian Ocean Dipole tending negative and this fueling rain events from west to east, propelled by the jet stream across the nation.
Widespread rainfall in the coming days will tip most of the coastal areas here above the average before any more rainfall develops throughout the period. The mechanics behind this rainfall event, look to be repeated a number of times through this period, but it will be the jet stream and the moisture inserted into that feature which will likely lead to above average rainfall chances to come beyond this rainfall event in the east over the weekend. The weather is forecast to be more humid along the coast with the onshore flow to feature, this running over elevated SSTs in the Coral Sea and Pacific Ocean, leading to more wet weather than normal for this time of year along the coast away from major rainfall events. Inland areas could see further dry season rainfall if we have northern cloud bands develop ahead of stronger fronts over southern Australia.
New South Wales
Widespread rainfall is expected to feature more often than not through this period, although with some luck the coming week should be much drier and warmer for many of you over the inland ahead of a colder shift next week. That wave train next week that forms over the nation is forecast to bring rainfall via the jet stream leading to widespread rainfall over much of the south and east. How much moisture can get involved into that remains to be seen but be aware, widespread rainfall is forecast to appear more often than not. Now be aware that the east coast likely to be wetter in the coming 3-4 weeks and possibly drying out towards the end of the period which at this time is early July.
The weather is likely tending wetter as we go through Winter and while it may be frustrating seeing green on the charts in some areas that are drier, it would be wrong for me not to drawn in at least a leaning bias towards above average rainfall given the climate signals. Now the bulk of the heavier rainfall totals still likely to be north of the state via the jet stream where cloud bands will feature. Along the east coast of the nation, onshore winds will bring above average rainfall, but that moisture could be drawn south into the southeast inland ahead of cold fronts with rainfall numbers coming up. I think most areas should at least see seasonal rainfall. Now that could also arrive in one system, or drawn out through dribs and drabs, but the rainfall frequency should increase.
The rainfall is forecast to move above the average in most inland areas and leaning towards above average over Agricultural areas as we move through this period. However, some modelling is forecasting well above average rainfall for the Ag Areas, but I think being cautious is fair as many are riding on rainfall actually occurring first, before even talking about above average rainfall. But like Victoria, the rainfall is forecast to come in dribs and drabs but could scrape towards at least seasonal values. But the idea is that the weather is likely turning wetter as we go.
%Chance of exceeding or not exceeding the median temperatures through the coming 6 weeks taking us through to the 4th of July 2022
Victoria and New South Wales
Chance of warmer weather into June as the pattern shifts, but generally seasonal most elsewhere. Watching the frost risk closely but may be overridden by higher humidity and warmer nights
Slight cooler bias running through the interior where the jet stream is present but generally seasonal weather most elsewhere with no strong bias for brutally cold or warm bias just yet.
Cool bias a near certainty for inland areas of the state.
The persistent cloud, rainfall and onshore flow will lead to the cooler bias through much of the state. The depth of cloud cover will determine whether this forecast verifies, but the signals are somewhat strong in the coming 2-3 weeks for well below average temperatures as a whole.
The Indian Ocean Dipole is forecast to develop through this period and with increasing warmth in the oceans around Australia, this will lead to higher moisture content and create warmer days and warmer nights. The daytime temperatures may be compromised further south where cloud bands form. The night temperatures are forecast to remain above average in most areas.
The dry season will be hotter and more humid that normal, especially about the northern coastal areas of WA through the Top End and over Cape York. There may be warmer than normal weather through to about Ti Tree in the NT but cooler than normal weather may be observed nearer the Alice through to Uluru where cloud bands may begin to feature.
The warmer bias over the north of the nation is in response to the more humid airmass in place. There may be some cooler weather over the far southwest, but this is conditional upon how much of the cloud cover from the interior gets involved in bringing more dark days with light rainfall. Most elsewhere, seasonal weather is expected but some of the temperatures along the coast could be warmer than normal if rainfall is less than what is forecast.
Generally seasonal conditions forecast across the country and that will be reflected through much of inland QLD and NSW, though we may see a cooler bias trying to nose into the western areas of both states as cloud bands increase in frequency on current guide. Warmer than normal days a slight chance over the Great Dividing Range with higher humidity leading to warmer than average nights as well.
Indian Ocean Dipole - NEGATIVE PHASE DEVELOPING.
The Indian Ocean is forecast to move further into negative territory through the period with warmer than normal waters building offshore WA, leading to more moisture being advected into the atmosphere and this drawn southeast across the country. This will lead to higher-than-average rainfall for many areas through Winter and more likely through Spring with heavy rainfall totals possible and flooding increasing for inland areas from Outback WA through, SA, NT and into the eastern inland, more likely NSW and northern VIC and nearby the ACT. Some areas could see flooding similar to 2016 which is something of concern for the food bowl in the east and southeast. Widespread rainfall will continue to the end of the year as we transition into the warm season so early onset rainfall is forecast over northern Australia. Also, to think about, the risk of severe weather season kicking off earlier than normal as well for QLD and NSW.
ENSO Region - LA NINA WANES SLOWLY.
The shift to a cool neutral influence from the ENSO region is forecast to continue throughout the Winter, with the seasonal override in place. This means that because we are in Winter, while there is a La Nina, it has little impact on Australia during this time, but does keep the warmer waters closer to the east coast of the country, but the prevailing wind regime is likely to be more westerly than easterly, so we don't see the impacts as per a Spring or Summer season. That said, the cool neutral/weak La Nina phase may help to keep the Southern Annular Mode more towards neutral throughout Winter, reducing the impacts of the westerly wind belt somewhat. This in times without the IOD in a negative phase would lead to a drier Winter for much of Australia, but I do think we will see the IOD take the reins from the ENSO in terms of major weather maker through this period. Now as we move into Spring, the ENSO should resume taking a role in influencing the weather for northern and eastern Australia. This leading to early onset rainfall and buildup, early start to the storm season and higher rainfall likely through harvest, in conjunction with the negative IOD phase, the nation looks to be swimming on paper, but in reality, these things look somewhat different. So be aware, make preparations but there is not enough information to panic yet. The peak of the next La Nina on current information is next January or February, if it forms. Current guide has risen to a 61% chance of formation through Summer 2022/23.
More to come on this during Tuesday when the next lot of data comes out.
ADDITIONAL KEY POINTS
More on this coming up throughout the weeks and months ahead.
I will have the next update on Climate during Tuesday next week. There is a lot of data to work through and I am looking at that throughout the weekend and more to come next week.