The weather turning quite active over the northern areas of the nation this week, TC Tiffany moving through Cape York today, is expected to take heavy rainfall from QLD through the Gulf and set to pound down over the Top End setting the stage for potential flooding over northern Australia. This is important for the remainder of southern and eastern Australia in terms of the medium term impacts on the weather.

More on that coming up later this morning.

For the southeast and east of Australia, the weather is set to remain soupy and unsettled on and east of a trough, which is retrogarding west through NSW and QLD today. Once the high moves through to the southeast of the nation, the trough will then get pushed to the southwest resulting in showers and storms returning to eastern SA and most of VIC by mid week.

Severe weather is possible with thunderstorms from Tuesday through the weekend as the trough deepens over VIC and into NSW and QLD. All modes of severe weather is on the table including one or two tornadoes a risk through VIC and much of NSW west of the divide.

For the remainder of SA and WA, the same ole song and dance continues, the hot and dry weather persists, but where the tropical system goes in the medium term may offer a pattern shift with humid weather and rainfall returning to these states.

Lets take a look


Rainfall Next 16 Days

Rainfall once again increasing in the short term window for the southeast and east again with the deepening trough and persistent moisture that is sitting over the eastern and southeast inland of the nation. Rainfall becoming heavy in spots and the flood risk returns for some locations over NSW and VIC. Tropical Cyclone Tiffany is generating heavy rainfall as advertised over Cape York with some locations set to record 200-400mm of rainfall with this feature. The tropical cyclone will move across the north of the nation but weaken into a monsoonal low over the NT spreading heavy rainfall throughout the NT but points south and east as moisture shears off this system into the jet stream. The northwest of the nation may only see an increase in showers and thunderstorms but if the tropical low moves further west then this would change. The remainder of the nation as you expect, dry and hot for the most part but that tropical moisture will likely begin to influence weather for WA and SA with showers and storms gradually returning.

Thunderstorm Forecast Monday

A similar spread in the modelling for Monday with storms impacting largely the same areas but the intensity of those storms could be increasing as we track through the afternoon and evening with heavy rainfall and damaging winds for the southeastern and eastern inland as well as running through northern interior. Strong and gusty winds, one or two water spouts possible for Cape York with the approach of the tropical low/cyclone.

Thunderstorm Forecast Tuesday

Thunderstorms capable of producing heavy rainfall leading to flash flooding possible over the northern and eastern interior of the nation thanks to a slow moving trough over the eastern interior and a middle level trough moving over the southeast during the day. A tropical low may also produce thunderstorms, some with intense rainfall and destructive wind gusts. Severe storms also possible about the Top End and Kimberly during the afternoon with the approach of a gravity wave off the tropical feature moving west through the north.

Thunderstorm Forecast Wednesday

Thunderstorms continue for the southeast and eastern inland of NSW and VIC with storms likely turning severe over much of NSW west of the divide and through northern VIC. Heavy rainfall and gusty winds likely the issues with thunderstorms, though the coverage not as widespread as Tuesday. Thunderstorms may also develop in eastern SA near the next trough forming over the state. Severe thunderstorms with dangerous conditions as Tiffany, a likely severe tropical cyclone, passes through the Gulf and into areas near Numbulwar to Borroloola with destructive wind gusts and a few isolated tornadoes. The damaging wind threat with storms will be felt right across the NT in the spiral bands rotating around the centre of the storm.

Tropical Cyclone Tiffany

Tropical Cyclone Tiffany will move over Cape York today bringing heavy rainfall and strong and gusty damaging winds to areas between Lockhart River and Cooktown and points west. Heavy rainfall from about Cardwell to Thursday Island and points west will continue today and tomorrow. The Tropical Cyclone will then head west through the Gulf on Tuesday, strengthening as it moves over the warmer waters of the Gulf and moving into favourable wind shear to reach severe status by the time we hit Wednesday. There is an outside chance the system becomes a compact category 4 before hitting the east coast of the Top End. The system will likely then weaken over land, but also slow down over the NT leading to a very high flood threat for the Gulf Country in the NT and QLD, spreading into the northern Barkly and Katherine regions. Heavy rainfall also likely to develop for the Darwin region and greater Gregory and Daly regions with flooding also possible as the system slows to a crawl. Heavy rainfall may develop for northern Kimberly region by the end of the week into the weekend.

Flood Watch Northern Australia

Very heavy rainfall of up to half a metre is possible along the track of TC Tiffany and then the remnant circulation as we move through this week. Big concerns for the river systems over the Top End, especially the Roper McCarthur, Katherine, Daly and Adelaide River Systems. Some areas may see more than a months worth of rainfall leading to communities being isolated and cut off for a number of weeks. Big towns such as Katherine and Mataranka need to pay close attention to the forecasts. This may extend to Daly River as well. Darwin will see areas of flash flooding with the drainage much more efficient.'

DATA - More information found in the video.

12Z Euro - Surface Pressure Pattern and Rainfall Distribution - Next 10 Days

The pattern clearly dominated by the the troughing over the nation and the persistent easterly winds, so no change to the forecasts. The humid weather being felt far and wide over the north and east and this will continue for the next 7 days. Showers and thunderstorms expected most afternoon and evenings over the eastern inland of the nation, peaking at times as short wave troughs pass through the region. The tropics, active, the Rossby Wave flaring TC Tiffany today and that system will dominate the weather for the northern third of the nation. Currently the wet weather is over north QLD, but as the system moves west, the heat levels will start to come down over the Top End and rainfall chances come up. The Kimberly will remain very hot and unstable with a few showers and storms, this will run down into the the Pilbara in WA. The heat values over WA and SA remaining high but in the absence of humidity, should be fairly seasonal for this time of year.

12Z Euro - Precipitable Water Values - Next 10 Days

The moisture values across the north and east remain very high and that is in part clearly to the tropical feature running through the north of the country, but the onshore winds over QLD and NSW pumping in that rich maritime air into troughs over the east leading to the elevated rainfall chances. The drier air continues to impact the same areas for the next week or so, the west dry, much of SA remaining dry nearer the ridge which is suppressing rainfall chances. There may be a shift in the pattern once we know more about the remains of Tiffany over the NT, whether she heads west or she ends up heading east or southeast. Makes a huge difference to the forecast.

12Z Euro - Rainfall Accumulation - Next 10 Days

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12Z GFS - Rainfall Accumulation - Next 10 Days

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12Z CMC - Rainfall Accumulation - Next 10 Days

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12Z Euro - Rainfall Accumulation - Next 15 Days

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12Z GFS - Rainfall Accumulation - Next 16 Days

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More weather coming up throughout the day. A reminder that I am in the NT so the morning weather information is delayed by an hour as per normal. Thanks.

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