NATIONAL WEATHER PICTURE - PM EDITION - TUESDAY MAY 25TH 2021.

Headlines


  • Rain with some moderate falls moving through VIC into NSW tonight.

  • Warm and windy over QLD and NSW.

  • Colder weather moderating over WA.

It has been a wet day across Western Victoria with falls of 5-20mm observed since 9am this morning. Even a few thunderstorms broke out over the central ranges of Victoria ahead of the rainband that is now sweeping through Melbourne through to Echuca and heading east bound into Gippsland and southeast NSW.


There have been showers and some local thunder and hail across southeast SA and into southwest VIC this afternoon, this could increase this evening as a low drifts just to the southwest of the region and another shortwave passes through.


Very warm and windy through parts of eastern Australia ahead of the large cloud band, with a good supply of sunshine and dry west or northwest winds. Temperatures through northern NSW and QLD will likely stay warm into Wednesday, but they will fall away over southern NSW as a consequence from morning rain and a westerly wind change, with upper heights coming down.


The cold airmass over WA is starting to ease, another light frost is possible on Wednesday morning before a mostly sunny start, but cloud is likely to renter the state from the west and north with a disturbances sitting offshore.


National Satellite - Tuesday May 25th 2021.

Extensive cloud covering the southeast is in association with a cold front that is finally moving eastwards. Rain has been rather extensive under this band through SA, VIC and TAS throughout Tuesday with some of that rainfall now sneaking into southern NSW, which will progress east overnight.


The cloud band is largely rainfree through outback NSW, SA and into WA where the upper ridge is in place keeping the airmass stable and the relative humidity values down through to the surface from the middle levels is quite low. Not supportive of rainfall.


Otherwise clear warm skies ahead of the front through NSW and QLD today.

A closer look at the low pressure system that is barreling through the southeast of the Great Australian Bight, some thunderstorms with hail has been observed in coastal areas of southeast SA and moving into western VIC this evening. This low is likely to dive to the southeast overnight and washout in the westerly flow tomorrow.


With the atmospheric dynamics becoming less robust over the mainland and pulling away from the southeast, the rainband will likely thin out and collapse during Wednesday, with high and middle level rain free cloud left over NSW and QLD during the afternoon and evening.


Southeast Australia Satellite Picture - Tuesday May 25th 2021.

Temperatures have started to respond to the rainfall that is moving through the east, but ahead of the rain it is warm, with well above average temperatures. Behind the front it is cooler. WA, the temperatures are still well below average while they are running above average over northern WA through the NT and over inland QLD.


National Temperatures - 3pm EST Tuesday May 25th 2021.

Spot the front in the southeast!!!!! And a nice band of rain in association with this temperature drop too.

Rainfall has been extensive over parts of southeast Australia today with some welcome rainfall we spoke about earlier. The rain is progressing eastwards and likely to thin out through Wednesday.


Radar - As of 3pm EST - Widespread rainfall over Central VIC with scattered showers and isolated thunderstorms on the eastern edge of low pressure and a shortwave in southwest Victoria.

Speaking of rain - rainfall for the coming 10 days looks reasonable with some decent falls anticipated over WA through the period and rainfall over southern areas, most has fallen today and tomorrow. Though we are now starting to see hints of more rainfall coming into the picture just outside of this window, so areas like SA, VIC and NSW should watch the forecasts closely as this chart could get a little more colourful in coming days.


Rainfall for the next 10 days - Valid Tuesday 25th May 2021.

GFS Rainfall data for the next 2 weeks - showing a bit more inland rainfall about - which is in line with now coming into the end of the first week of June. There could be some interesting weather lurking about the place coming into Queens Birthday Weekend too.

We will start with the surface pressure pattern showing that once this front and rain clears the east of the nation during Wednesday, all eyes are back on SW WA with another major storm event likely to bring heavy rainfall and strong winds through the weekend and into next week.


GFS has decided it doesn't want to dive that system south now, rather meander it eastwards through to SA, which is a game changer for the south of the nation, because if that does indeed verify, maybe some follow up rainfall can be put back on the table next week, but for now I am keeping that chance quite low.


Further ahead, the weather may become more spicy as we get into early June with the long wave trough becoming active and giving eastern areas of the nation a chance to see rainfall in early June which would be a bonus!


MSLP for the coming 2 weeks, with precipitation. GFS 00z run valid Tuesday May 25th 2021.


Upper air pattern for Tuesday evening, showing the low (you can see on the satellite) washing out into the westerly wind regime near Tasmania and rain and showers starting to decrease as this process takes place, hence why it is dry for central and northern NSW in this event.

By tomorrow morning, the front is on by, new high pressure is taking control of the weather through the mainland, despite the large amounts of cloud about the place, the air is stable and the airmass dry, so little rainfall expected over inland areas on Wednesday. A cooler southwest flow over the southeast states will keep the showery windy weather going, with another short wave passing through Bass Strait within the airmass.

Modelling is fairly benign beyond the front moving out of the southeast during Wednesday. A large high is anticipated to set up camp in the Great Australian Bight from Thursday, helping to propel a major wintry front through the Tasman Sea, which could generate some very big seas in the Tasman and colder air for the east and north if it verifies.

A new storm system will move closer to the WA coast during Friday afternoon or evening, and by the weekend, a large wave of low pressure should move through, with a band of rain and thunderstorms. Some moderate to heavy falls are possible once again. Some areas this week have seen 90-120mm of rainfall and it is conceivable that the same areas could double their rainfall.


By Sunday, the front stalls out and a pool of cold air will race northwards to meet the front and a low will develop in response. Somewhere through the SWLD should expect severe weather to develop this Sunday or Monday with the placement, timing, intensity and scale still to be determined. This is a heads up for some wild weather coming up.


Upper air pattern shows a multi centred upper low with a deep surface forming underneath that, driving strong winds, showers which may turn to areas of rain with locally heavy falls. Thunderstorms will small hail also possible and snowfalls for the Stirling Ranges is possible if the coldest air moves ashore. This latest run is not as cold as this morning's run but the thickness values have been down as low a 5400 which is quite cold for this region.

That system, if it cuts off from the westerly wind regime, may meander east and could bring some rainfall to western SA this time next week, but confidence in forecasting systems like that, are very low. Upper lows = weatherman's woes!


Upper air flow pattern from GFS wants to bring the system east slowly, bringing cloud and patchy rainfall into western SA before the entire system washes out. Euro is not so keen on that idea and keeps the system over southern WA before diving it south into the Southern Ocean with little impact for the southeast states. Will continue to watch trends as it is more than a week out.



Some interesting weather lurks out in the distance, this event here would bring some significant cold air into the southeast with the potential for widespread rainfall over the east with the west turning dry and milder. A pattern flip would not be an unlikely idea given the current set up but it is more than 10 days out and will likely change.


Upper air pattern - June 6th 2021. Showing a deep trough over the east driving colder weather from the south and west with a front bringing rain and thunderstorms to the eastern and southeastern states. But as always this is a long way out and will likely change, but if you read the climate update outlook today, this type of weather is likely to unfold this winter over Australia.


The overall pressure pattern is very much screaming late Autumn over Australia which it should for the final week of May. No major heat events are anticipated at this time, though one severe weather event is likely to be on the board over southern WA later this weekend, which will be monitored.


Would you like more weather information for your part of the world? Get in touch at karllijnders@weathermatters.org





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