CLIMATE - RAINFALL AND TEMPERATURE OUTLOOKS - APRIL THROUGH JUNE 2022

THE FORECAST

%chance of exceeding or not exceeding the median rainfall for April through June 2022

%chance of exceeding or not exceeding the median temperatures for April through June 2022

THE ANALYSIS

The latest update for April through June 2022 is now available. The data sets are starting to converge on the idea of a slower waning of the La Nina in the Pacific which would generate more humidity and rainfall potential over the north and east and the persistence of elevated SSTs across the remainder of the waters surrounding Australia.


The area of interest to watch is the in the Indian Ocean and over the Southern Ocean for Southern Australia with the higher SSTs supporting above average rainfall as the emergence of westerly winds return to the charts. Frontal weather could be more productive that usual with the elevated SSTs in the region. That is not uncommon after the Summer Season, but it does appear the elevated SSTs may persist.


Also the late tropical cyclone activity that may emerge off the warmer waters of the Central Indian Ocean, could increase the chance of rainfall being derived via the jet stream, pumping in moisture from this region into WA and possibly SA in advance of cold fronts.

So we will have to factor that risk in when the frontal boundaries return to the charts, IF the above tropical weather continues to emerge in the final weeks of the wet season. Watching that MJO very closely in the weeks ahead. It is likely the next wave will pass to the north of Australia as well, but they can spawn some pretty powerful April cyclones.


We have already seen in recent weeks the level of moisture running through the westerly winds south of the nation and through the Indian Ocean as well, so once that lifts north, it could be a productive start to the wet season in SWLD of WA and then spreading eastwards thereafter.


00Z GFS - Precipitable Water Anomalies - Next 2 Weeks.

Perhaps the seasons are shifting and we are likely to see rainfall become more organised across the nation from the northwest/west through to the southeast/east, balancing out the bias that has been the east/north rainfall dominance for Spring and Summer? Healthy signs for an early wet in the west.

Over the north, we are likely to see a protracted period of rainfall and humidity, a slow start to the build up which could be retarded under the current guidance by about 3-4 weeks. So it may not be until June, that we see the drier southeasterly surges come back in with some force. Another tropical low or cyclone is possible off the region in the next week.


In the east, the persistent La Nina through April and into May now, this could help the SAM neutral to positive a little longer than normal enhancing the rainfall spread throughout the coming 4-8 weeks before the westerly wind belt gets involved. The wet weather in the east may decrease for a period, but over eastern inland areas, it may continue to be above average with the influence of the elevated moisture levels from the waning La Nina and then the westerly wind belt may also contain elevated moisture levels that may keep the rainfall going.


ENSO Outlook from February

Suggests that the climate models are slowly waning the La Nina event and it should be resolved by May and neutral values are expected by June throughout the basin. Only a couple outliers can be seen either side of neutral, so that is the most likely outcome to call a NEUTRAL phase for the ENSO. Means minimal impact for the nation at this time from mid May onwards.

For southern Australia, watching those westerly winds, the heightened level of moisture over the northwest, north and then via the westerly wind belt all converging through southern and southeast Australia. We can already see some of those moisture streams coming through the southern parts of Australia with large high and middle level cloud bands racing through. Once we get low pressure attached to these areas of deeper moisture, then rain bands will likely develop.


Late February

Could see the weak influence from the northwest through to the southeast

Mid March

Can see a stronger connection between the Indian Ocean (MJO) and the more wavy jetstream projecting cloud and some rainfall across the country.

So while it has been a little quieter after a record start to the rainfall for scattered pockets of the country, it is likely turning wetter once again throughout the next couple of months as we transition out of Summer into Autumn and then ease into early Winter.


MY CURRENT OUTLOOK AND GUIDE

%chance of exceeding or not exceeding the median rainfall for April through June 2022

The chance of rainfall exceeding the average through this period remains very high over northern areas of the nation where the lingering wet season is expected to last through to about May. April itself could bring months of rainfall above the norm so by the time we hit June, this outlook could have verified for the north. Elsewhere, a high chance on and east of the divide through QLD and NSW, just grazing the ACT and into the eastern parts of VIC. Once again the chances of above average rainfall falls away to a flip of a coin through western VIC, NSW and into much of Ag SA. With the elevated SSTs and the signals from the climate data sets, the rainy season for SWLD of WA may kick off earlier this year with moisture surging in via the upper level northwest winds over the Indian Ocean, being drawn into cold fronts and seeing larger rain bands develop out west. The current signal from the climate data sets is that the high pressure may be anchored out over the Bight into the southeast inland deflecting rainfall chances for now. But this will continue to be monitored.

%chance of exceeding or not exceeding the median temperatures for April through June 2022

Temperatures will likely follow the current trend of being led by where the upper high pressure sets up over the nation. At this time, the sub tropical ridge is forecast to move north as per normal from the south of Australia, but there is a chance that there could be periods of blocking high pressure over the southeast and east, leading to rainfall being deflected to the south and west of the region. That would also mean a higher chance of further easterly winds for eastern Australia leading to cloudier days, and more showery weather as the wet season continues. Over in the southwest, with the above average rainfall signals being observed, I am softening the chance of above average temperatures for now and leaning below average is fair. Finally up over the north, we will see significant risks of widespread above average temperatures which will be in direct response to the above average SSTs and lingering La Nina leading to lingering moisture keeping the temperatures up. It could be delayed start to the dry season. If you are in the white, a flip of a coin chance of being above or below the average, so you are in the seasonal zone for now and values could exceed or not exceed the average within tolerance.

DATA SETS

RAINFALL ANOMALIES - APRIL THROUGH JUNE

IRI Rainfall Outlook - % chance of exceeding or not exceeding rainfall for April through June 2022

Generally speaking this model is suggesting seasonal (white/yellow) to above seasonal (green/blue) for the next 3 months. The rainfall looks to increase through the coming fortnight with the MJO rotating through northern Australia and possibly increasing the risk of cyclone activity developing during this period. That would increase the risk of moisture travelling through northwest to southeast through the nation. Above average rainfall is a very high chance over the northern tropics, especially QLD. That would be good for areas that have observed a failed wet season, so farmers through the region would really benefit from that. Rainfall through the remainder of QLD mildly above average which too would be welcome to Central QLD which has missed out a bit too. Mixed odds for the southeast if you believe this and that mixed odds extend through southern Australia and into the west. But as I keep mentioning, all it takes is one or two tropical features crossing through the inland and this forecast becomes wrong after a few weeks. So fingers crossed it is wrong for WA and SA, where rainfall would be of use. Good to see this model moderating rainfall across the east coast of NSW.

Euro Rainfall Outlook - % chance of exceeding or not exceeding rainfall for April through June 2022

The Euro is way more aggressive on the wetter signal and it has performed fairly well throughout the past year with the excessive rainfall signals and them verifying in reality for much of the nation. The light green shading is suggesting leaning wetter than normal, the blue shading well above normal. The wet weather will be focussed with the prolonged wet season over northern Australia and that will be lifting north as the monsoonal trough and wet season retreats naturally to the equator through May. But lingering moisture may lead to lingering diurnal showers and storms and the onshore flow over the east coast of QLD could lead to above average rainfall through to the end of June. The Indian Ocean is warmer than normal at the moment and the model here picks that being the case through June leading to enhanced rainfall spreading through from northwest through to the southeast. Seasonal weather of much of the nation can be expected, but many of you will see somewhat above average rainfall, especially in the east and north.

TEMPERATURE ANOMALIES - APRIL THROUGH JUNE

IRI Temperature Outlook - % chance of exceeding or not exceeding temperatures for April through June 2022

A warmer season for the north is a higher chance based off the lingering higher humidity and rainy season, this not allowing the temperatures to dry out during May. And that is a high chance, based off the retardation of the La Nina phase in the ENSO and the lingering above average SSTs around the nation. For the southeast and south of the nation it will be generally seasonal, but I would not be shocked if we saw the values remain below average over parts of southwest and central WA with the increased rainfall chances near tropical weather. That may snuff out the heat values for the remainder of the hot season, leading to more seasonal weather across the nation for April onwards. That too would be welcome for the west and parts of the south that are drier than normal.

Euro Temperature Outlook - % chance of exceeding or not exceeding rainfall April through June 2022

The Euro is also suggesting mostly seasonal temperatures for most of the nation with only a few pockets leaning above average. This is again down to the above average SSTs around much of the waters surrounding Australia. I do think that the north of the nation will be warmer than normal, especially against what is being shown here. There could be some locations in the west and about the east coast, that could be below average through April and again during June, with May looking much warmer as the subtropical ridge starts to move northwards.

A LOOK AT WINTER VERY QUICKLY

RAINFALL ANOMALIES - JUNE THROUGH AUGUST

IRI Rainfall Outlook - % chance of exceeding or not exceeding rainfall for April through June 2022

More on this coming up in the next few days - but certainly some signals that the wetter weather may increase across the nation during the Winter.

TEMPERATURE ANOMALIES - JUNE THROUGH AUGUST

IRI Rainfall Outlook - % chance of exceeding or not exceeding temperatures for June through August 2022

The above average temperatures may persist over northern Australia? Could that indicate a failed dry season with more humidity? Or is that indicating a persistent hot dry airmass? The south of the nation looking relatively seasonal for now. But more on this coming up in the coming days.

I will have a look at Winter and Spring next week - I am just waiting on more data sets to come through but it will only be a brief overview of where the current guide is at, nothing more. It is important to say that the further you go out, the less accurate the forecasting is....THAT IS ACROSS the board.


No one has possessed the skill sets, not even computers, to give accuracy beyond 5 days it seems. So use this as a guide and more details can be added as we go along as these posts are updated.


Finally you can track back to all my climate information by heading to the climate section, just select that when filtering out posts to see everything over the past year.

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