Winter weather is about to pounce on southern Australia during the next fortnight, with a significant amount of frontal weather moving over the country.
And it looks to be a wet phase for the south and east yet again with a deep low then a westerly wave train.
Rainfall for the next 10 days - Valid Friday June 4th 2021
The Southern Annular Mode is expected to trend negative over the coming fortnight, lending itself to another burst of strong westerly winds expanding north from the South Pole bringing up cold air and showery weather.
Southern Annular Forecast - Valid June 3rd 2021.
Note the positive surge over the coming week, and we find a cut off low with high pressure on either side of the nation. The westerly flow cut off to the south. The a negative surge is forecast and the westerly winds return mid month. Lets see how that verifies.
In the short term we have a significant low that will cut off over the southeast of VIC/NSW bringing widespread wet weather and severe weather, which is coincidentally in line with a positive SAM phase, but the short term deterministic chart shows that quite nicely. In some respects, those needing rain got lucky with this system coming up.
GFS 18z run - 500mb/18000ft flow pattern showing the movement of the fast flow pattern following the deep upper low over southeast Australia. Note the northward progression of the westerly wind profile over much of Australia once the block in the Tasman Sea resolves.
The weather becomes quite wet over WA in line with the next long wave trough approaching form the southern ocean bringing strong and gusty winds, and bouts of heavy rainfall along frontal weather moving in from the west.
The rainfall will likely kick off Wednesday with a weakening front and strong winds and showers and storms. The stronger system is Thursday and Friday with a broad band of rain developing over the west coast and extending further inland with a colder shift. From that point on, a front every 24-36hrs should be expected on the current guidance into mid month.
Rainfall for the next 10 days - Valid Friday 4th of June 2021
Rainfall totals will continue beyond 10 days through the west and extend further inland possibly a northwest cloud band too for outback areas into SA.
Precipitable Water Values/Moisture through the atmosphere will be running through the jet stream and extending into northwest WA and drawn south and southeast through the country. At this stage, some of the fronts pick up moisture but the lifting mechanism is not quite in phase, however this could change as we get closer to each front passing through, so the rainfall charts will be adjusted accordingly to account for those changes.
Precipitable Water for the coming 2 weeks GFS 18Z run - Valid Friday June 4th 2021 - showing modest amounts getting involved into each system, but really wanting to see a large 50mm impulse of moisture to come into a front from the NW of the nation down through to central Australia and then the southeast for areas that have missed out in recent months.
The temperatures will be quite warm to start the new week, but there will be a large drop in line with the upper level low forming and dragging in the cold dry air from the south, which will fold over the southeast with snowfalls developing over Alpine areas and possibly surrounding elevated areas in VIC and NSW.
Temperature Anomalies - Monday 7th of June 2021.
Mild to warm and windy weather over the southeast on Monday with a ridge parked over NSW. A strong northwest flow will drag in that central interior warmth. Gales will develop later in the day.
Temperature anomalies - Wednesday 9th of June 2021.
A surge of cold dry and windy weather brings widespread colder than normal weather for the nation mid to late next week with a lovely dry surge coming into the NT. Wild weather in the southeast may bring snowfalls to widespread areas if the low sits in the right spot. That remains to be seen.
Snowfalls look limited with the low sitting in a warmer spot and the winds being more south to southeasterly. Some snow of 20-30cm for Alpine areas will be welcome none the less but some moderate snowfalls may develop over the ACT and Southern Highlands and Snowies. Light snowfalls into the Central Tablelands and Northern Tablelands also possible, but we have seen many looks at this in recent days.
Snowfall forecast for the coming 10 days - GFS Valid Friday June 4th 2021.
Winds will reach gale force early next week over the southeast, with wind warnings likely to be issued for multiple states for a number of days.
Monday and Tuesday, northwest gales of up to 100kmh are possible ahead of the rain band, then cyclonic southwest to southerly winds may reach gale force over the southeast coast. Westerly gales on the northern flank of the low may form on the east coast south of Coffs with gusts to 110kmh.
Wind forecast - Euro 12z run for Monday afternoon.
Wind Forecast - Euro 12z run - Valid Tuesday morning.
Wild weather developing for the east early next week remains highly likely. Who gets what remains a mystery, but know that there is inclement weather coming where there could be multiple issues for farmers and graziers.
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