Apologies on the broad update this evening, TC Tiffany is having other ideas about my ability to get more information out tonight, so I thought I best get this broader update out before I cannot post with the next band of storms coming in.

The nation is seeing fairly typical weather for Summer albeit humid and unsettled for much of eastern Australia with a continue under broad easterly winds. A trough is set to deepen into this airflow and you guessed it, more showers and storms for eastern SA, VIC, NSW, the ACT and western QLD. The tropical weather over the north linked to the ghost of Tiffany as she works across the north bringing temperatures down and heavy rainfall.

From the weekend and into next week, the remains of Tiffany is expected to move southwards and then south throughout the nation, bringing inland rain and thunderstorms. It remains to be seen whether we see widespread flooding with the event and where/if that occurs. Modelling from the majors has been poor, with the outlier models handling it better. ICON has shown it's skill in the short term bringing that system across the Top End faster, reducing the risk of flooding for the NT. That is some good news.

Next week the north and east of the nation will remain unsettled with showers and thunderstorms continuing for the east and north of the nation, some heavy and there is the chance of more organised rain event on the horizon. But timing, scale and intensity still to be worked out.

Lets take a look


Rainfall Next 10 Days

The heaviest of the rainfall across the country is currently heading west bound over the NT with the remains of Tiffany as she weakens. A strong northwest flow on the north of the feature will bring heavy rainfall to the northern and central Top End and clearly near it's centre. It should be near the WA/NT border tomorrow and then over the Kimberly on Friday before starting to turn southwards into the NT once again during the weekend and washing out over the Outback. Copious amounts of moisture will be spread across the nation next week leading to widespread showers and thunderstorms with areas of rain. The final sharp pressure trough is set to bring showers and thunderstorms to parts of the southeast and east from tomorrow, some of that could be heavy but your rainfall number will vary from model to model and that means it comes down to thunderstorms. That activity should contract out of the southeast during Friday and over the weekend with the trough slowly lifting out. The remained of SA and WA looks dry and sunny under the ridge but that moisture out of the north may make an impact at the very end of the period.

Tropical Cyclone Tiffany

Tiffany has moved inland and begun to weaken. She already looks like a tropical low again. As mentioned this morning, she looked to be moving faster as per the GFS solution and that has verified in real time. The modelling overall has struggled with this system and continues to do so. The system will bring heavy rainfall and gusty winds to the Top End over the coming days and that will extend to the Kimberly before the whole complex moves south over the weekend and weakens over the Tanami or Barkly.

Flood Watch NT

Flooding is expected to be minor to moderate now over the NT and that extends into the eastern Kimberly, which is good news as the cyclone thankfully will be steered faster to the west and then will find a gap in the ridge to the south and begin to move in that general direction away from the NT over the weekend into next week. Flash flooding still a high chance.

Thunderstorm Forecast Thursday

Thunderstorms are forecast to develop across eastern SA and western NSW and northwest VIC during Thursday afternoon and evening. Storms are expected to organise into multicells with flash flooding a high to very high risk through the pink zone. There will also be a risk of damaging winds and large hail as well in this zone. The thunderstorms are expected to be more scattered in nature through central VIC and NSW, and the risk tapers off further north through NSW and eastern VIC. Thunderstorms may develop into a squall line over northern VIC and southern NSW where damaging winds progress eastwards. Storms may also turn supercellular over parts of eastern SA and western NSW during the afternoon and evening where giant hail and destructive straight line winds/isolated tornadoes are possible.

Flash Flood Risk Thursday

A high to very high risk of flash flooding with severe thunderstorms along and to the east of a surface trough over the west of NSW and eastern SA. Some storms could drop more than 50mm in an hour.

Damaging Winds Risk Thursday

Damaging winds are a very high risk through eastern parts of SA near a trough, as storms form and strengthen over the region. The storms will progress eastwards into NSW and northwest VIC mid to late afternoon and there is a moderate chance of damaging winds with a squall line moving further east through NSW and VIC at night.

Large Hail Risk Thursday

Thunderstorms that form immediately on the trough will carry a moderate to high chance of producing large hail through the afternoon and evening. The focus of the hail risk slowly moves eastwards towards western NSW and northwest VIC during the late afternoon and evening.

Tornado Risk Thursday

Thunderstorms that turn supercellular, carry the risk of giant hail and isolated tornados in the areas identified.

DATA SETS - Refer to the video for more information on the below data sets and the breakdown of the short and medium term.

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

More information in the video where I break it down daily.

00Z GFS - Precipitable Water Values - Next 16 Days

Once again the rule of thumb is moisture will follow the tropical systems and this will impact rainfall, that is why you are seeing great variation in your numbers right across the nation away from the southwest and far south.

00Z GFS - Rainfall Accumulation - Next 10 Days

Refer to the video for more information

00Z CMC - Rainfall Accumulation - Next 10 Days

Refer to the video for more information

00Z GFS - Rainfall Accumulation - Next 16 Days

Refer to the video for more information

12Z Euro - Rainfall Accumulation - Next 15 Days

Refer to the video for more information

More weather coming up from 830am EDT tomorrow - I am struggling to get some decent coverage out here in Katherine town at the moment where the weather is turning pretty hairy at the moment.

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