A better way of covering off tonight's update is looking at the impacts from the major rainfall event that is likely to sweep the nation from northwest to southeast. The questions that will remain in place surrounding this will be;

  1. How far south does the ridge lay over the southern states? This will impact how far south the rainfall comes through SA and VIC. The high may deflect rainfall east through NSW and QLD

  2. How heavy is the rainfall set to be? That will come down to the speed of the tropical plume of moisture.

  3. Does the system get stuck over the eastern inland of the nation and combine with easterly winds to bring heavy drenching rainfall to NSW and QLD?

They are the key points tonight that I will address in the update and charting.

In the short term across the nation, we have the tropics in a monsoonal northwest flow with showers and thunderstorms, some heavy leading to flash flooding. A trough over the east and southeast tonight bringing severe weather, warnings have been in place over southeast NSW and eastern VIC for those. The focus of thunderstorms will likely shift north through NSW and into QLD this weekend. And still baking hot over in the west with significant heat lows promoting very high temperatures with an upper high overhead supporting the high 40s for another few days.

Lets take a look


Rainfall Next 10 Days

Rainfall is expected be widespread and heavy across the nation over the next 10 days with 2 major rainfall events on the board, the first coming through with the remains of Tiffany, the other another deep trough likely to form over the central or eastern areas of the nation into the medium term offering another round of heavy rainfall for the nation. The tropics remain seasonal with the ongoing monsoonal showers and gusty storms about. The activity is expected to increase further over tropical areas later next week with another tropical low forming in the monsoon trough offshore. This low more likely to impact WA at this stage, but strengthens that northwest flow over northern areas. That will pump further moisture into the nation while the ongoing rainfall events continue. For SA and WA, it really is a line ball as to how much rainfall in fact comes your way. Tricky forecasting due to the pressure pattern being very finely balanced on where high pressure sits in relation to low pressure, how fast shortwaves pass through, this playing havoc with the overall forecasts so for now the forecasts remain low confidence.

Modelling Next Week

The models are still all over the board but most are now supportive of the southeast kick towards Central Australia over the weekend and into early next week and then the moisture spreading through NSW and into QLD. Where they disagree on is the presentation of that moisture southwards. How far south it goes remains to be seen with models struggling in the medium term. For now this chart expresses the divergence and backing a horse is exactly that right now, gambling on one model over the other is not weather forecasting or good decision making. We have to be patient and wait for trends. The pattern is certainy favourbale for flooding rainfall for large areas of the inland, but once confidence improves, then charts will be issued here.

Areas to Watch Agricultural Areas

The rainfall very much a knife edge for SA Ag Areas, better coverage of rainfall is expected for the food bowl in the east with significant risks of brown rot etc impacting some crops through this prolonged humid and wet period.

Thunderstorm Forecast Saturday

The remains of Tiffany is expected to move southwards and merge with a trough over inland areas of the nation leading to more widespread showers and thunderstorms developing during the day with locally heavy falls leading to flash and riverine flooding. The same can be said for the east with storms continuing from Friday into Saturday and this will contract was through the day, with further thunderstorms likely to form, leading to all modes of severe weather possible for QLD, NSW and the ACT. Clearing conditions through VIC. Afternoon storms possible near a developing heat trough over in the west and gusty showers and thunderstorms possible over the Top End.

Thunderstorm Forecast Sunday

Thunderstorms will continue over much of northern Australia with the remains of Tiffany being drawn into a deep trough triggering widespread convection. Thunderstorms possibly severe over a wide area of the interior with heavy rainfall the main issue. There may be damaging wind gusts further towards QLD.

Thunderstorm Forecast Monday

Thunderstorms will continue in a broad zone across the country with heavy rainfall leading to flash and riverine flooding the main issues out of this tropical incursion of moisture. Storms may be gusty close to the low pressure system as it passes through the interior of SA and NT before shifting into western QLD/NSW. Dangerous flash flooding is possible through outback areas between Alice Springs and Yulara. Gusty storms are also possible over the the Top End and Kimberly in a northwest monsoonal flow.

Flood Watch NT/WA

The flood watch remains in place with warnings now in force for Central Top End Rivers after 2 days of heavy rainfall. The warnings are likely to emerge over the Kimberly after 200mm of rainfall in some locations overnight and further heavy rainfall for the next 2-3 days. This will likely be extended into the northern interior of WA and the western side of the NT tomorrow in the Saturday Update and then further east as we go through Sunday and into next week.

Tropical Depression Watch - January 20-27th 2022

Another wave of low pressure is expected to form off the NT coast and move westbound into the Indian Ocean during this time. It will likely encounter better wind shear and form into another cyclone. How long it stays over water and its proximity to the coast will determine it's strength but some models ramp it up to a substantial system in the medium term. This is very typical following excessive heat values over the region for the past few weeks. This is the response to that.

DATA - More information in the video at the top of the page.

00Z GFS - Surface Pressure Pattern and Rainfall Distribution - Next 2 Weeks

A very dynamic pattern is set to unfold. Refer to the video above to find out more.

00Z GFS - Precipitable Water Values - Next 2 Weeks

The very deep moisture profile should be with the majority of the nation through the coming 2 weeks. The other ingredient needed to see rain and storms develop, low pressure, will also be floating about and will dictate ultimately who cops the worst of it over the coming week or two. The red shading coming down into southern Australia is cause for concern related to flooding and then for eastern Australia.

00Z GFS - Rainfall Accumulation - Next 10 Days

More information in the video at the top of the page.

00Z CMC - Rainfall Accumulation - Next 10 Days

More information in the video at the top of the page.

00Z GFS - Rainfall Accumulation - Next 16 Days

More information in the video at the top of the page.

More details coming up tomorrow morning at some stage, again I will focus on the rainfall event with a brief overview on the short term, need to recharge my batteries ahead of next week, it is going to be busy and I want to be able to cover it properly for you all.

Have a great weekend.

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