MODELS AND ALL THINGS RAINFALL - THE WET END TO SUMMER AND BEGINNING OF AUTUMN LIKELY FOR MANY.

The north and east are looking increasingly wet and unstable as we go through the coming week as anticipated by the climate drivers moving into phase across northern and eastern Australia to support more widespread rainfall. The SAM remaining positive for the coming week and the MJO also moving through northern Australia in the next 1-2 weeks is expected to lean towards wetter weather in these zones.


For southern and western Australia, the wild card is the tropical weather working it's way around northwest Australia. This could lead to moisture being drawn throughout the inland.


If the SAM turns neutral and then negative, then we could see moisture drawn southeast through the nation from WA across SA and into VIC. This is classic late season Summer and early Autumn rainfall.


A reminder on the risk of flooding for the coming fortnight, the analysis is unchanged on the current guides.


Flood Risk Forecast - Next 2 Weeks

Flooding over northern and eastern areas of the nation remain a moderate chance, tending high near the coast with a low risk extending inland. The low chance is being drawn in over much of NSW and QLD and extending into northeast and eastern VIC. I am leaving the rest of the nation out of the risk for now with no clear guide on the tropical systems impact on the country. However a tropical system moving west away from the NT through WA and into the western interior is possible but not highly probable at this time, but an event like that could bring flooding risks back to the charts over western and central parts of the nation so for now just a be on watch situation for these areas.

SHORT TERM

The short term once again dominated by the positive SAM and the MJO rolling through northern Australia. So that is where you find the rainfall at its most productive. The majority of SA and through southern WA should be dry through the coming week though some falls may start to appear from late in the weekend over southern WA.


UKMET - Rainfall Next 7 Days - MODERATE CHANCE

Note the tropical weather building north of the nation and the heavier rainfall over the east of the country as well. Not much weather for the west and central parts of the nation as well advertised.

ICON - Rainfall Next 8 Days - LOW CHANCE

Heavier rainfall building north of the nation and along the east coast as supported by the climate drivers. The weather over the central and western parts of the nation remaining settled if this is right, through to next weekend.

MEDIUM TERM

The MJO is expected to remain over northern and northeast parts of the nation will see the tropical weather stay active with widespread falls. Tropical cyclone activity remains high across all waters of northern Australia and more guidance on that through the week as the data tracks the monsoon in real time. Expect more changes to the forecasts for northern Australia relating to this and then the impacts of where these tropical entities form will then play out over the remainder of the nation, so nationally, rainfall forecasts beyond about 5 days remains low.


CMC - Rainfall Next 10 Days - MODERATE CHANCE.

Heavier rainfall over northern and northeast Australia with the stronger monsoonal feature over the NT and QLD region. The wet weather in the east with the onshore flow will see heavier showers developing, especially in the presence of an upper trough moving over inland portions of QLD and NSW adding support for thundery weather inland. Light falls with a heat trough in WA.

EURO - Rainfall Next 10 Days - MODERATE CHANCE

The Euro placing two tropical systems on the board, one over the Cape York region and the other out in the Indian Ocean, with a monsoonal trough in between bringing heavy rainfall. Upper trough in the short term spreading the instability through a deep moisture profile leading to enhanced rainfall over the eastern regions, particularly central and eastern QLD, NSW and the ACT. Drier weather back west but could see falls increasing for the west with moisture shooting off the tropics.

ACCESS - Rainfall Next 10 Days - MODERATE CHANCE

Access has a tropical system near Darwin and a deeper monsoonal flow over the NT and QLD. That is where you find the rainfall in the period, with drier weather for WA. The weather over the east very wet, the trough is further west over the SA/NSW border leading to more widespread rainfall for all of VIC, NSW and much of QLD with flooding falls on the east coast possible. Drier further west though falls come up with an upper trough deepening later in the period.

KMA - Rainfall Next 12 Days - MODERATE CHANCE

Similar to the ACCESS and Euro, showing tropical weather responding to the monsoonal flow north of the nation, can clearly see it there. Tropical low forms near Cape York and another tropical system off the QLD coast near Townsville. Heavy rainfall developing near a stalled trough over the eastern inland of NSW but like ACCESS has the trough further west extending falls into eastern SA. Rain developing over the west later in the period with an amplifying upper trough.

GFS - Rainfall Next 16 Days

Tropical lows developing near Darwin and another off the coast near Broome and another near Weipa through this period. Which one wins out as the dominant will change from run to run, therefore changing the impacts down the line. Bottom line wet for the north. The east wet with the positive SAM and prolonged period of easterly winds feeding a stalled trough. Classic La Nina weather. The west drier than the other models but is the only model to take the tropical system through inland areas.

ENSEMBLE DATA

Broadly wet and unstable over northern and eastern Australia with rainfall redeveloping for the remainder of the nation as we move through early March. The SAM tending neutral and then possibly negative will help to bring back the moisture and rainfall over the southern and western parts of the nation, IF there are tropical lows/cyclones further west of WA.


GFS - Rainfall Next 16 Days (median of 35 members) - MODERATE CHANCE

CMC - Rainfall Next 15 Days (median of 30 members) - MODERATE CHANCE

EURO - Rainfall Next 15 Days (median of 51 members) - MODERATE CHANCE

LONG TERM


CFS - Rainfall Next 6 Weeks - MODERATE CHANCE

The broadly unstable and wet weather will continue over the nation's north and east over the coming 2-3 weeks and the wet weather over the east coast will also continue with the residual of the positive SAM in the short term and the emergence of the positive SAM from mid to late March and possibly into early April. We are seeing more variability in the SAM throughout this period which may support the spread of moisture across the nation, rather than dominating the east and north,.

More coming up from 8am EDT Monday.

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