EXTENSIVE INLAND FLOODING TO CONTINUE.

The monsoon trough is way south of the tropics at the moment leading to extensive flooding and ongoing flood risks. It is also placing a lot of the east under significant flash flood risks with thunderstorms.

Narranderra, Albury, Mildura, Melbourne, Young, Tibooburra, Delta, Louth, Tilpa, many locations through the Eyre and Yorke Peninsulas in SA have experienced significant flash flooding and will continue to see this over coming days before a break.


But the ongoing Riverine flooding over the heart of the nation back to the tropics is likely to see widespread disruption across the region this week, which will have major impacts on supply chain issues over northern Australia.


FORECAST CHARTS


National Flood Risk - This Week - January 30th through February 4th 2022

Excessive moisture levels at near record levels will result in rainfall mirroring that, at record levels where low pressure is present. At the moment, we have an active area of low pressure over the heart of the nation in combination with the monsoon trough and that is expected to drive heavy rainfall and flooding through the areas outlined in darker green. Remember, you do not need it rain at torrential levels for you to experience flooding impacts in your community or region. The rainfall will gradually move south and the moisture then propelled eastwards, in combination with another trough, taking the heavy rainfall risks towards northern SA and then far northern NSW and southwest QLD. Heavy rainfall may lead to flooding in addition to the moderate to major flooding in place already. Much of the NT has seen above average rainfall in the past few months and this rainfall if it verifies will see flooding become even more extreme in some areas down the Stuart Highway between Tennant Creek and Marla. The rainfall will contract north to the tropics by next week with a drier picture for the second week of February likely at this stage, with the focus of heavy rainfall shifting to the east coast of NSW and QLD and through the far northern tropics.

DATA

18Z Euro - Latest Rainfall Guide 3 Days.

Excessive moisture over the northwest Kimberly will be sheared southeast through eastern WA into northern SA and the southern NT in the form of a solid rain band with embedded thunderstorms leading to flash and riverine flooding. The rainfall may also extend over far northern NSW and southwest QLD with a month to two months rainfall possible in these areas. While the whole of the NT is under a flood watch of some variety south of the Top End, it is important to note that thunderstorms will lead to high end flash flooding. The most intense rainfall is reserved for areas bound from Broome to Derby through to the inland deserts south and east from there.

18Z Euro - Latest Rainfall Guide 5 Days.

This is the broader data set which offers a similar spread, less intense, in the idea of rainfall over the coming days. These values are very high and robust across the 51 member set through northwest and inland areas of the nation. The monsoonal weather up north is bringing seasonal conditions and the east coast looks to get some thumping rainfall mid to late week one the moisture arrives from the west of the nation, into a stalled trough. This too may lead to severe weather over eastern Australia later in the week into the weekend coming. The overall risk of flooding for inland areas will begin to recede from later in the week into the weekend, but there may be some communities cut off for weeks.

18Z Euro - Pressure Pattern - Next 3 Days

Note the very deep moisture profile lifting into that extensive area of rain and thunderstorms over northern and central Australia, then being drawn into a trough passing through the southeast in the coming days. What happens through northern SA and then into NSW and QLD needs to be watched closely. If a low pressure system forms within the trough moving east Tuesday or Wednesday, with PW values near 3 inches with this feature which record values, there could be some locations regardless of what public forecasts or data sets you are looking at, for people in this region, you could see 50-150mm in a sitting from thunderstorms. As outlined above, a few centres in NSW and VIC have already experienced that, and no forecast, data set etc will be able to pin that nasty weather down ahead of time, just be aware that it is possible. For the north of the nation, significant rainfall and windy weather to continue with the tropical low. Models struggling to pin this down to. So where it goes will impact the moisture spread downstream from this feature. So rainfall totals may continue to chop and change as we go along for northern areas of the nation with flood risks also moving around a bit.

18Z Euro - Precipitable Water Values 3 Days.

For central areas of the nation, it does not get any more saturated than this. Excessive moisture levels coupled with deep layer instability, means a lot of rainfall for areas that should be entering their driest and hottest phase of the Summer. This is an incredibly anomalous weather event and models will not know how to handle that, with very little previous data to go off. We have to go back to the 70s to see something similar.

Rainfall Next 10 Days

Rainfall remains very much above average for much of this period nationally, but more likely to be felt over the north, central and eastern areas of Australia. It has been a very wet end to January as promised and this is likely to spill over into early February before we get a little break on the very wet weather. The northern and central parts of the nation look to cop the wettest weather for now under persistent high moisture levels and low pressure. The east coast may see an increase in showers and thunderstorms this week and into the weekend with onshore winds and a pressure trough nearby leading to much more widespread rainfall on and east of the divide. This may stretch into southeast QLD. For VIC and SA, the weather largely becoming drier for southern areas of the state, but over northern SA into Central Australia, will have to keep watch on that very heavy rainfall shield coming from the tropical low that is in the monsoon. That may bring another belt of 100-200mm of rainfall over areas that have seen significant flooding. The west remains dry for now but the moisture should begin to increase from the north and east into the SWLD later this week into the weekend. Into the medium term and rainfall is expected to increase over eastern and northern areas of the nation with the SAM remaining positive and the impacts of the peaking La Nina over the past week begin to be felt across the country.

Thunderstorm Forecast Sunday.

More thunderstorms are expected over a wide area of the nation with the risk of dangerous flash flooding once again possible over the central parts of the NT, spreading west into the WA region. Flash flooding also a high chance back through to the eastern inland and a high chance with squalls over the NT and Cape York. Damaging winds also possible over parts of the NT with showers and storms.

Thunderstorm Forecast Monday

Thunderstorms remain a high risk over a broad area on Monday. Severe thunderstorms are most likely over northwest SA into the eastern parts of WA and much of the NT with a deep moisture profile, multiple troughs and a tropical low all combining to produce heavy rainfall and dangerous flash flooding. There will be high humidity back over the south and southeast with scattered afternoon storms with the chance of heavy rainfall once again away from the coast. The drier air and more stable air over the east of QLD is thanks to a ridge.

Thunderstorm Forecast Tuesday

Thunderstorms are likely to continue on and east of a trough through SA, VIC and into the ACT and NSW. Storms have a high chance of producing heavy rainfall leading to flash flooding and damaging winds. For northern areas of the nation, through the central NT and into QLD, heavy rainfall leading to flash flooding is a very high risk with thunderstorms. A monsoonal low over northwest WA will begin to move southeast and take the severe weather risks through central areas of the state and possibly into the far north of SA. Thunderstorms over the Top End and Cape York may be gusty with damaging winds.

Thunderstorm Forecast Wednesday

A flush of dry air over southern areas of the nation will see the storm risk contract north and east out of the southern states with high pressure ridging in. Thunderstorms on and north/east of a trough through NSW, SA and WA will lead to widespread showers and thunderstorms, some severe with heavy rainfall and flash flooding the main concern. The monsoon trough will continue to trigger squally showers and storms over the northern tropics with the possibility of damaging wind gusts.

Remain weather aware with the severe thunderstorm warnings in the east as we have seen excessive rainfall of up to 150mm in the past 24hrs in some isolated spots which has lead to once in a generation flash flooding for some communities. This is starting to unfold again today. For areas over inland Australia in the green shading, ongoing extensive riverine flooding is with us for a while and be sure to make final preparations for the worst and hope for the best.