A wetter June expected for western and southern Australia with above average frontal weather expected
Drier than normal through QLD and northern NSW
Warmer than normal for large parts of Australia
Cooler weather for the southern and western coasts is expected.
No real change from the last update for June with a strong signal that the Southern Annular Mode will trend negative during early June, leading to a wet and windy start to the month with colder than normal weather expected.
The negative SAM leads to drier than normal weather for parts of the northern and eastern sections of the nation with a prevailing westerly wind profile bringing in the drier and warmer air from the northwest of the nation.
The main driver for the month of June will likely be the Southern Annular Mode. It is likely to stay negative for the fortnight from late May into June. That leads to wetter weather over southern and western Australia and drier weather over northern NSW and QLD under such events. Valid May 18th 2021.
Rainfall signals are improving for southern Australia from recent reliable signals, where the more unreliable modelling is suggesting a very dry month for all of Australia. I am keeping the dry signal for much of northern Australia (obviously with the dry season in full swing that is standard) with that dry signal extending into northeast NSW and much of QLD. Again not unheard of for this time of year.
GFS Extended Rainfall - Taking us through to mid June - Valid May 18th 2021.
Euro Extended Rainfall - Valid for June 2021. Note the heavier rainfall signal for inland WA extending into SA and VIC. Valid May 18th 2021.
However with the chance of moisture being dragged in from the deeper Indian Ocean through June, this may allow cloud bands to develop over the course of the period with rainfall chances picking up for inland areas, but this a conditional risk as we go through June. You can see above in the Euro run from this morning that it is conceivable that rainfall could increase for inland WA, SA and into NSW and VIC through June, again not strong enough on my read to bring up % chances for those regions.
Rainfall signals remain very strong for coastal areas of WA and the adjacent inland of the SWLD extending east through the southern coastline into the Agricultural regions of SA and through much of VIC and TAS as well as southern NSW and ACT. The east coast in a prevailing westerly wind regime, largely stays dry but if there are stronger fronts moving through, then periodic rainfall is likely under such scenarios.
So with that data analysis, I have pushed the below average rainfall risk further north from the last update with a better chance of above average rainfall over southern Australia. But remember, it is a 60% chance of above average rainfall for June, means there is a 40% chance of average or below average rainfall too. So look at the % from both sides to make the decisions appropriate for you.
The drier signal from GFS is based upon a dry end to the month of May with high pressure holding out, but this is unlikely as we track through the coming week, based of short term forecasts with a pattern flip on the horizon. Valid from now until the 20th of June 2021.
In contrast, the Euro ensemble shows a wet signal for the month of June with the potential for widespread rainfall developing over WA and extending into SA and VIC throughout the month. Cold and showery weather will extend into southern NSW frequently with good snowfalls possible. Though falls will be lighter through NSW. Valid May 18th 2021.
Climate Outlook - June 2021. % chance of exceeding mean rainfall for the month of June 2021. Valid Tuesday May 18th 2021.
Temperatures are largely unchanged for the period, with a slight strengthening of the cooler signal over parts of WA and the southern coastline with showery periods and strong cold fronts likely to lift the colder air from the southern ocean and drape that over the southern states.
This does bode well for rainfall potential and for snowfall outlooks into June and we could see reasonable precipitation accumulation through the period over those areas exposed to a westerly wind regime.
Over northern areas, under the climatic signals being analysed, warmer and drier weather is expected for northern and northeast areas of the nation, prolonging the dry spell over QLD.
Euro Ensemble Temperature anomalies - valid May 17-July 2nd. This does show a warm bias that is currently in place with this current high pressure, but once we lose that, we will see a colder trend over WA and through the southern states and the heat shift to the north and northeast. Valid May 18th 2021.
So not too many changes to the temperature outlook, but it must be noted for areas in the south, significant periods of colder, windy and showery weather will put stock under threat from cold losses.
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