The weather has been really interesting of late, the transition out of the severe weather for the east now into this period of flux where we wait to see how the neutral SAM phase impacts the south, whether that overrides the wet phase across the east coast or whether we continue to have moisture stream in atop high pressure anchored in the Tasman Sea leading to more inland rainfall developing. There are rumblings of that next week, but will we see the SAM turn positive in the medium term?
Also the impacts of the MJO moving over northern Australia, will that hang around and deepen the moisture profile over the northern and western parts of the nation initially, and will that moisture be spread throughout the remainder of the western, southern and into the southeast interior, for areas that have missed out? Can we see that Autumn Break potential?
Lets take a look for the period March 18-25 2022 (I am now covering off the next week rainfall potential for the south and east in separate posts in the coming days and the state based forecasts).
Moisture Watch Next Week
Moisture is becoming more complex in the medium term and into the end of the month and that is in part due to the uncertainty surrounding the status of the Southern Annular Mode with the driver likely to be neutral but a decent spread of the members suggesting a negative phase coming through the back of the month which would whip up the westerly winds. If this is in conjunction with an in phase MJO (enhance tropical weather) it may allow for the moisture to be drawn across the nation via the more wavy jet stream allowing for cloud bands to develop throughout the nation, lifting the chances of inland rainfall for many areas inland of the coast, especially for those in WA and SA. This shift is something I would like to see to confirm that we are moving closer to an Autumn break, not only in terms in rainfall but in temperatures, to bring down those very warm temperatures in WA. So the moisture will be a key component to the spread of rainfall clearly, but also will paint the picture of what the upper level winds are doing and once we see a more wavy flow across the nation, we could be on for more moisture being dragged across the country, especially for WA through SA and into the eastern inland.
Rainfall Accumulation - March 18-25 2022
This is a guide and not a highly confident forecast because it is medium term and this is a blend of all the latest guidance I have reviewed this morning. So at this stage we could be dealing with persistent rainfall in the east with the lingering trough left over from late next week, there is evidence that it could become stuck over NSW and QLD (some modelling also sees another ECL for the NSW coast but overall the confidence in specifics is low). The north still unsettled with scattered showers and storms continuing, watching closely for any late season cyclone development as well. For the south and west, there is likely to be another wave of frontal weather passing through the Bight, which could lead to moisture being dragged down from the Indian Ocean with patchy rainfall developing under broad cloud bands. The interior for now looking dry and this could encroach northern SA, western QLD, western NSW and into eastern WA.
Rainfall Anomalies - March 18-25 2022
The confidence as mentioned not espeically high, however we are seeing a trend of the eastern inland and coastal areas of NSW and QLD seeing a reasonable chance of above average rainfall. There could also be above average rainfall for pockets of the tropical north. Across the southern coastal areas of SA and into WA, frontal weather may bring patchy rainfall with light to moderate rainfall, with seasonal expectations at this time. The areas between the tropical weather to the north and the modest northerly movement of the westerly wind belt should remain dry for now. However, this period of the year can be volatile. As we will see next week, we were likely to see drier weather developing, now we are seeing yet another rainfall event of note. So stay close to forecasts as the period carries a low confidence nationally.
Temperature Anomalies Next Week
Still looking warmer than normal for many inland areas, especially over northern SA, through the southern NT and back into much of inland WA. The east may see seasonal values now in the wake of the upper level low and rainfall event that should be moving eastwards by the time we get to next weekend. Frontal weather also emerging through the Southern Ocean may lead to warmer weather being pulled southeast from the interior into the southeast inland, but this could occur towards the end of the month into early April. Tropics, remaining above average with higher humidity values and seasonal weather for the east coast overall.
More coming up in the state based forecasts this evening.