The weather is looking very active for large parts of the nation as we track through the coming weekend and into Australia Day Week. We have a few items on the board that will likely bring severe weather.
A tropical low/cyclone over the northwest of the nation will certainly be a feature to watch, which is expected to impact either the NT but more likely northern WA and hopefully bring an end to the high heat over interior parts of the nation.
The other area of severe weather potential is over southern and eastern Australia with a deep trough and low pressure system passing slowly through SA, VIC and NSW with the risk of a multi day storm outbreak.
The remainder of the nation looks fairly seasonal for now.
Rainfall Accumulation - January 24th-31st 2022
Low confidence rainfall forecasting continues over the course of this period with the myriad of weather systems across the nation providing severe weather opportunity, but the consistency of placement and scale remains difficult as models diverge during this period. So for now we will keep the forecast broad. Wettest weather through SA and throughout VIC and NSW with a deep trough and low pressure system. Another tropical feature will introduce the monsoonal flow over northern Australia with the core of that low/cyclone bringing enhanced rainfall, but once again, placement of this feature is tricky and will take time to pin down. Drier weather for the southwest of WA and perhaps for some parts of QLD with the troughs favouring western QLD.
Tropical Depression Watch - January 20th-27th 2022
Tropical depression may form as early as Thursday up over northern parts of the Arafura Sea and track southwards. The upper level winds and SSTs are favourable for development into a cyclone, but it needs to stay over water and avoid the island chains north of the nation. One way or the other, enhanced rainfall later this week over northern Australia is likely with a developing low off the Kimberly Coast by the weekend.
Severe Thunderstorm Risk - January 22nd-27th 2022
A deep trough over the central parts of SA is expected to form during Friday and across the weekend, deepening further, pulling in high levels of moisture with the risk of severe thunderstorms over a number of days. Storms will carry the risk of heavy rainfall leading to flash flooding and damaging winds. Hail is a very low risk. Thunderstorms will progress towards the east during the weekend and over the course of next week and Australia Day.
18Z GFS - Surface Pressure Pattern and Rainfall Distribution - Next 16 Days
Very heavy rainfall over outback areas will continue today before easing during the coming day or two, and that moisture then moves into the trough over NSW and QLD. But a new trough that forms over SA during the latter part of the week will pull that moisture in from the east and widespread showers and thunderstorms will likely break out with severe weather potential this weekend and into next week. Locally heavy rainfall leading to additional flooding is possible Saturday through early next week. The weather is expected to be more humid and unsettled with widespread showers over northern and eastern Australia ahead of the trough and low pressure system passing through the southeast of the nation. This will also carry severe weather potential. Depending on the tropical system over the north of the nation, this may bring additional heavy rainfall over northern WA and this may run across the nation again, however some models do keep this system further west over the Indian Ocean so that will be a feature to watch.
18Z GFS - Moisture Content and Distribution - Next 16 Days
Very high moisture content coupled with the low pressure can be seen across the nation from the weekend into next week, this is where you will find the severe weather risks across the weekend into next week. So much of SA that has been dry are now looking at a pattern flip this weekend and into next week with a multi storm outbreak with heavy rainfall leading to flash flooding a risk. The northern tropics also very unsettled with moisture increasing over the weekend and into next week with the tropical feature and then the monsoonal northwest flow. That monsoonal flow will play a part in delivering deeper moisture across the nation during the early part of February.
18Z GFS - Moisture Anomalies - Next 16 Days
Exceptionally high moisture content is expected to sweep the nation this week, with the remains of Tiffany, but it is the resurgence of moisture that passes through through the northeast winds once the high gets into the east. Values are about 250% above normal! That will lead to widespread showers and thunderstorms with heavy falls over SA, VIC and western NSW through this weekend and into next week before drier air surges in as the trough clears east. Up north, the tropical system that emerges through the Timor Sea may bring another surge of deeper moisture over northern Australia into the medium term, with the monsoon also laying over northern Australia.
You can see from the broader data sets below that the active weather is set to continue for the nation through the coming 2 weeks, especially in the second week of the outlook for the northern parts of the nation and through the central and eastern parts of Australia as well. Most areas should see 1 month's worth of rain through southern and central Australia on current guide within the next 2 weeks. The north of the nation will see an additional half months worth of rainfall, locally higher with the tropical feature. The only dry spot is over in the SWLD of WA where moisture does return but the lack of instability to lift the moisture into meaningful rainfall still remains the problem.
18Z GFS - Rainfall Accumulation - Next 2 weeks
18Z Euro - Rainfall Accumulation - Next 2 weeks
18Z CMC - Rainfall Accumulation - Next 2 weeks
More coming up in the state based forecasts this evening.