The weather is expected to remain quite volatile offshore to the north with multiple tropical lows in the process of developing near large clusters of convection. The risk of depression formation is very high over the course of the next week.

Some of the modelling suggests a tropical low may form in the short term, as early as tomorrow but other models suggest over the weekend. The region is currently under the influence of the MJO which enhances rainfall chances through northern Australia and the risk of tropical cyclone formation.

For the southern areas, looking drier now, as the onset of monsoonal weather looks to be reserved for northern parts of the Top End so I have removed the impacts of the tropical moisture for now, but that may shift into March so keep watching.

Lets take a look


Rainfall Next 10 Days

Rainfall is looking more likely north of Tennant Creek with moderate to heavy falls further north of Elliot. The weather is expected to be quite dynamic over the far north during the weekend and next week as tropical lows drift on by creating heavy areas of rain and strong winds. But the guidance is poor on this so make sure you check back daily to the guidance and have your weather radar handy. The wet weather looks likely to linger into next week with below average temperatures and windy weather developing as the monsoon strengthens but the drier weather will likely persist over the south so need for a chart for that region.

Thunderstorm Forecast Wednesday

Thunderstorms are likely to increase in coverage over the northern Top End with the approach of small scale low pressure systems to the North Coast. The storms may be gusty with the presence of tropical lows nearby and if they develop overnight. Flash flooding for now would remain offshore but storms over land could see some areas record 20-40mm in an hour.

Tropical Depression Risk - This Week

With the monsoonal flow developing over the open water during this week you will notice larger clusters of thunderstorm activity. These clusters may become more organised and low pressure systems may develop. Given the elevated SSTs through the region (not as elevated as per January but it is sufficient) depression formation is quite likely from later this week and through the weekend. Refer to the chart to that shows you where the models are placing the tropical depressions and where they ago. The confidence in identifying the system that is the dominant tropical low is very poor.

Tropical Cyclone Risk - This Week

With the monsoonal trough sitting over the open water and the MJO passing through the north of the nation from the weekend and into next week, any tropical low that forms in the waters offshore the coast, carry a moderate chance of developing into a cyclone. The most likely outcome based of analogue data is that a system will form north of the NT and then head west through the Arafura, Timor and then Indian Ocean. That will then deepen offshore northwest WA and then turn towards the Pilbara and then inland through WA. That would spread heavy rainfall over the northern tropics but then pull the heavy rainfall shield away from the NT and over WA and another pulse of monsoonal weather would develop over Cape York.

DATA - Refer to the video for the break down on the short and medium term weather for the region

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

The GFS out most of the models this evening is struggling with the flow pattern. It is complex and the placement of the troughs in relation to the moisture will determine the rainfall coverage. Every run is still very much divergent from the previous and this will continue so I am keeping my assessment the same for the short term. For the medium term, the SAM remaining positive would keep the wet weather going over northern and eastern Australia, but if the SAM tends neutral, this will help extract moisture out of the northwest and drag it south and southeast through the nation and bring up rainfall chances for WA, SA and then VIC once again with troughs passing out of the west through the Bight and into the southeast. The east coast in the short term looks very wet, some of which has been experienced today. No time to play catch up in the forecasting game, use that as reference as that pattern will repeat many times through the wet season on the east coast with the waning La Nina.

00Z GFS - Precipitable Water Values - Next 2 Weeks

Moisture remains highest over the north and east through the bulk of this period but also starts to shift through central and southern Australia with some locations looking at copping some deeper moisture into the medium term. This will help to promote rainfall to expand across inland parts of the nation and developing over the SWLD as well as moisture is pulled into inland troughs, breaking the dry Mediterranean Summer.

00Z GFS - Rainfall Accumulation - Next 10 Days

Refer to video for further information

00Z CMC - Rainfall Accumulation - Next 10 Days

Refer to video for further information

00Z GFS - Rainfall Accumulation - Next 2 Weeks

Refer to video for further information

A closer look in - I suspect the GFS is off with the rainfall so refer to the models and rainfall outlook this evening from 9pm EDT.

A broader look.

More details coming up with the models and all things rainfall update later this evening.

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