The weather is turning severe along parts of the NT east coast this morning with the approach of TC Tiffany. The system is currently a category 1 and is likely to strike the eastern side of the Top End this afternoon as a 2, she is moving a little quicker than expected.

The usual nasties are expected for the region today, that rainfall and flood threat then moves inland this afternoon and through Thursday, Friday and into the weekend. The modelling has been shocking in terms of who gets what, initially keeping the heaviest of the rainfall over QLD, then near Katherine. This morning the main axis for the heavy flooding is further west which is now placing the higher flood risk further to the west and along the path of Tiffany.

Over southeast and eastern Australia, it is very humid this morning with a northeast flow in place. The wave of low pressure from yesterday is on by and things have settled today, though there will be pockets of showers and storms about today, and some of those could be severe, the coverage is a lot less than yesterday.

The next wave of low pressure in the upper atmosphere is set to arrive for the southeast and east on Thursday and this will likely lead to more severe weather risks, that could be in relation to whether a low pressure system forms on the trough or not.

Over the weekend the tropical system could be anywhere up north the way the modelling is going meaning being able to forecast specifics is very tricky, even 3-4 days out. So keep watching.

The higher confidence forecast is over in the west and much of SA, more dry weather near high pressure, the theme of Summer thus far.

Lets take a look


Rainfall Forecast Next 10 Days

Rainfall as mentioned, tricky to forecast but here is the latest guide. It carries low confidence still and is dictated by Tiffany to the north of the nation. The southeast has one more storm outbreak to get through which will be through tomorrow into the weekend, the coverage of thunderstorms uneven as per yesterday so some copping a belting and others not so much. It will be impacting the same regions. The weather for the remainder of southern Australia through to WA should be fine and dry for this week at least though with the increasing moisture over northern Australia, we may start to see that change, as that moisture creeps southwards post Tiffany and the monsoon flow establishes.

Tropical Cyclone Tiffany

Tiffany has moved to be off the coast of the Eastern Top End this morning, moving faster than the modelling and the BoM forecast track suggests, so this storm may only cross as a 1. That is good news in relation to flood risks down the track given that the system is not only moving quicker but also weaker so it won't take as long to wind down. The overall threat is the same however, dangerous flash and riverine flooding possible and damaging to destructive winds. The system is anticipated to move more freely now through the Top End and could cross into the eastern Kimberly before turning south and being absorbed by a wave passing through southern Australia. Tiffany will also help to bring in unstable northwest winds over the northwest coast leading to monsoonal like conditions.

Flood Watch NT

As mentioned a very high risk of flooding is likely to continue along and to the south of the system as it moves into the NT today and then the system is expected to slow down over the Katherine region and points west now, so the flood risk has shifted further west and southwest of the Top End. Flash flooding is also a very high risk along the path of the cyclone today.

Severe Weather Alert - NSW and VIC - Thursday through Saturday.

The risk of severe storms develops on Thursday through western VIC and NSW before slowly translating eastwards on Friday with the most potent weather expected to be over northern VIC and on and west of the Great Dividing Range including the ACT. All modes of severe weather possible on Thursday and Friday with the passage of the deep low and trough, including isolated giant hail and tornado activity. The risk contracts eastwards on Saturday with the main storm focus sitting over the eastern half of NSW, the ACT through to southern QLD. The risk eases by Sunday, severe storms still possible in pockets throughout northern and eastern NSW but would have cleared VIC and southern NSW by Saturday afternoon. More defined risks and forecast charts will be issued in advance of this event.

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

Thunderstorm Forecast Thursday

Thunderstorms likely to continue right across the north with dangerous thunderstorms with destructive winds over the NT quite possible. Thunderstorms expected to turn more widespread over the southeast with a trough deepening through SA. This trough is expected to bring a risk of severe storms, with all modes of severe weather possible.

Thunderstorm Forecast Friday

Thunderstorms contract slowly eastwards on Friday with the low deepening along a trough over the southeast. This will create a dynamic environment for thunderstorms to turn severe, all modes of severe weather is possible with the chance of some giant hail and destructive winds in a few storms. Thunderstorms will stretch into QLD but these will be less severe than further south. Strong storms continue for northern Australia, some severe with heavy rainfall leading to flash flooding.

DATA - Refer to video for more information

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

A very low confidence on the track of Tiffany into the medium term means what you see beyond about Sunday is likely to change. The weather very hum\id over northern and eastern areas of the nation with the tropical moisture unable to be swept out with the troughs and low pressure keeping it in place and the new cyclone also adding more moisture to the picture. But where does the moisture go with this feature? The models are unsure so this will impact weather nationally, and as soon as there is more convincing guidance, then forecast confidence will improve.

12Z Euro - Precipitable Water Values - Next 10 Days

The moisture once again all connected to the tropical weather over the north. The lingering moisture over the east in the short term is still from the remains of Seth and the trough that will not leave. The next pulse of moisture is connected to Tiffany, and this is proving very challenging to forecast given that the models are still diverging quite a bit at the moment. That is making it quite challenging to forecast where the moisture will end up going into the medium term. But as you can see, the Euro places the moisture now straight south through the NT into SA.

12Z Euro - Rainfall Accumulation - Next 10 Days

More information to be found in the video

12Z GFS - Rainfall Accumulation - Next 10 Days

More information to be found in the video

12Z Euro - Rainfall Accumulation - Next 15 Days

More information to be found in the video

12Z GFS - Rainfall Accumulation - Next 16 Days

More information to be found in the video

I will have more throughout the day - pending the power stays on with this wild weather up here. The weather pattern is dynamic over the coming 2 weeks and so be aware that it will very humid and unsettled for the remainder of January for large parts of the nation leading into a very wet February.

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