This is a very dangerous period of weather for areas such as the Katherine, Adelaide, Roper and Daly Rivers. People in these areas should prepare for flooding and not just minor flooding, but moderate to major flooding, with a slow moving tropical low washing out over the inland, dumping copious amounts of rainfall for days.

The latest guide is relatively unchanged across all models, heavy rainfall and destructive winds looking to impact Groote Eylandt at some point on Wednesday before the system moves inland Thursday and slows down to a snail's pace on Friday through the weekend near Katherine before adopting a southerly track next week.

The stalling out period will result in very heavy rainfall under the area of circulation that could exceed 500-700mm over a 3 day period. So will have to watch where she goes very closely.

Darwin will be sitting under converging unstable northwest winds, some of those could be strong and squally with heavy bands of rainfall and thunderstorms passing through for about a week, ending this very warm monsoonal break period.

With the system moving southwards, moisture will increase for the Barkly and through to the Simpson Districts with widespread showers and thunderstorms developing next week.

Lets take a look


Rainfall Next 10 Days

Rainfall is expected to become widespread and heavy in the days ahead, developing from east to west, with widespread falls over 300mm expected near the path of Tiffany as she works in from the east. The speed of the system is not overly swift, so she will dump a lot of rainfall over a number of days. The most significant rainfall is anticipated where the system stalls out, that looks to be between Katherine and Daly River at this time, with extensive heavy falls leading to high end river flooding across the Top End. The bands of rain and thunderstorms will expand outwards from the centre of the storm as she weakens so expect widespread falls across the Top End from Thursday through next week with the system moving away at the end of the run, leaving the monsoon behind.

Tropical Cyclone Tiffany

The cyclone has crossed over Cape York today and will move steadily west, losing some strength as it passes over land, losing it's source for maintaining strength, but once back over the open waters of the Gulf, she is likely to strengthen rapidly into a Cat 2 and then a major Cat 3 by Wednesday before approaching Groote Eylandt by Wednesday afternoon as a high end Cat 3 before crossing the mainland shortly there after at similar strength. The system will then wash out over land and dump a tremendous amount of rainfall, turning the system from a wind and rain event on the coast to a major flood risk over the Top End.

Flood Risk This Week.

I cannot tell you how concerned I am about the flood risk for the Top End, but it is very high. So if you know anyone living along the river systems mentioned please let them know to prepare now!

Thunderstorm Forecast Tuesday

Thunderstorms are expected to increase over the Top End on Tuesday with the approach of the TC through the Gulf. Converging airmass with a rotating bands of energy around the system will help flare up thunderstorms. A strong line of thunderstorms is likely to develop out over Arnhem Land and sweep west through the Top End. A squall line making the Daly later in the day if not into Wednesday depending on the speed of Tiffany.

Damaging Winds Risk Tuesday

Damaging winds with thunderstorms a moderate to high risk across the eastern Top End with thunderstorms forming in advance of Tiffany.

DATA - More details on the GFS and CMC guide in the video.

00Z GFS -Surface Pressure Pattern and Rainfall Distribution - Next 16 Days

This is a low confidence forecast as we work out where the steering currents take Tiffany and ultimately that will drive the weather nationally as mentioned throughout the day.

00Z GFS - Precipitable Water Values - Next 16 Days

The deep moisture profile is something that all models have in place but the difficulty will be in teaming the deep moisture with adequate areas of low pressure, where does the tropical system go? Many of these parameters need to be answered before your rainfall and temperature forecasts will carry more confidence. So keep that in mind.

00Z GFS - Rainfall Accumulation - Next 10 Days

More details can be found in the video.

00Z CMC - Rainfall Accumulation - Next 10 Days

This is the more plausible solution and more details can be found in the video.

00Z GFS - Rainfall Accumulation - Next 16 Days

I am leaning away from this solution, but note that this will change a lot in the coming days and your number will change constantly. The drier areas will be the west and south, the wetter areas will be north and east.

A closer look in - note that I am siding with other models, but this gives you an idea of what is on the table as we move through the remainder of the month.

More details coming up tonight on all things models and rainfall from about 9pm EDT.

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