The pattern is shifting and we already have a fairly decent rainfall event across the southeast of the country today with a band of rain marking the boundary between the cold air to the south and the warm to hot air to the north.
That little bit of moisture that had built up in recent days providing periods of high cloud across the south is now being lofted into this rain band producing the welcome falls over Ag areas of SA, through VIC and into southern NSW in the coming days.
The remainder of NSW and QLD, really warm to hot today with a west to northwest wind and gorgeous beach weather across the east coast.
Out west conditions cloudy for inland areas but mainly dry weather for large areas of the southwest. We could see some rainfall developing off and on during the coming week with that rainfall moderate in sparsely populated areas as another weak upper trough tries to form.
But under the current climate guidance the major rainfall event is likely to form over eastern areas of the nation with the SAM remaining positive and leading to more moisture building up over the eastern and central parts of the nation. Increasing signals that an upper trough is likely to form in SA and possibly further east but the location is key to how this event unfolds.
As I am sure you are well aware, modelling has been giving and taking away large rainfall for sections of the country and this will continue to happen as we get a handle on how the event unfolds, but locking in decisions around this early data is not a good idea. I will have more analysis in the state based forecasts later today.
For now, rain with relieving falls and welcome falls across large swathes of Ag Australia is underway and that could turn heavy at times with local thunder. Tropical weather starting to ease for the NT and across portions of QLD, but the rainfall could come up over the FNQ and into Cape York.
Otherwise the interior dry until the weekend coming but this is where we will have to watch closely together. I have mentioned many times that the weather for the second half of April would be wetter and volatile with the warmer weather gradually easing over southern areas.
Lets have a look
Rainfall Next 14 Days
Rainfall is underway over southeast and southern inland parts of the nation as a trough with a southerly change slowly moves through today, clearing out of western VIC tonight and meandering through eastern VIC, southern NSW and the ACT during Tuesday. Light and patchy falls may arrive over northern and central NSW later Tuesday before everything is off the east coast by Wednesday. Coastal areas expect showers to develop with better rainfall production following the cloud band with onshore winds returning. These may become more unstable as we go through the coming mid to latter part of the week as we see a more unstable northeast to easterly flow developing. Widespread showers may develop over inland areas of the nation as moisture from the FNQ coast (where daily rainfall is ongoing) starts to move south and southwest through the nation. Some of this moisture may begin to work with the trough over inland areas to cause areas of rain and thunderstorms from as early as this weekend for inland areas of SA, through western NSW and QLD, possibly even southern NT. Out west, we have to watch the approach of a long wave trough which could also bring a separate band of rain to the west and southwest coast with moderate falls and a cloud band for interior parts. All of this running into the instability out east to create an environment for more widespread rainfall across the country. This will likely be the time of the Autumn Break looking at the guidance which could produce some great follow up falls to what is ongoing today. So all areas of the nation should be watching this event very closely.
Thunderstorm Forecast Monday
Thunderstorms are possible on the northern and eastern face of a rain band pushing through the southeast today which could pick up rainfall rates. Some thundery weather continues for the northern tropics, mainly over the eastern Top End and across Cape York where falls could be locally heavy.
Thunderstorm Forecast Tuesday
Thunderstorms will be a low risk under a cloud band over the southeast and mainly on the periphery of the cloud band. Thunderstorms will continue over parts of the northern tropics but more likely over Cape York.
Thunderstorm Forecast Wednesday
Thunderstorms should contract through NSW and eastern VIC with the departing rain band. Isolated showers and thunderstorms possible over the western interior near a weak trough and the showers and storms should contract east over Cape York during Wednesday where the higher chance of convective weather remains.
Thunderstorm Forecast Thursday
Cool stable air for much of the nation is expected with only a few very isolated thundery showers possible over the far north. The unsettled weather returns to inland areas of the south and east from Friday into the long weekend.
Thunderstorm Forecast Friday
Tropics remain somewhat active with a scattering of showers and storms. There may be some thundery weather developing with a change out west building offshore and thunderstorms may develop over inland areas with a trough deepening and moisture drawing in from the northeast to northerly winds in the upper levels.
MEDIUM TERM - April 25th - May 2nd 2022
Deep moisture across the nation looks to spread rainfall and the Autumn Break for many areas. Another moisture surge over northern Australia with a tropical wave passing north of the nation is possible with increased humidity and late season falls for the far north. This moisture too could be drawn south or southeast into the nation lifting rainfall chances. Another wave of low pressure passing through from the south of WA could surge northwards and bring a colder drier airmass towards Australia, which may help to promote another rain band forming in Southern Australia at the end of the period.
The anomalies are shifting above average as we move through the period with many areas now leaning towards a wetter bias for the period, thanks to the secondary system on the charts we can see over ANZAC Day and another system lurking out there in early May. Now in pinning down who gets what relating to rainfall totals, that is not possible, but you can clearly see the areas identified as being wetter than normal. And a good chance for many of you.
Becoming cooler as more rainfall and cloud cover takes over the nation with the warmer than normal weather of this week moving further east and north across the country with a colder shift for the southwest, south and eastern inland quite possible as we move into May. Warmer signal developing for the northwest and west with a persistent easterly flow as the east sits under the positive SAM influence leading to more cloud and rainfall.
DATA - Next video is due out this afternoon.
12Z Euro Surface Pressure Pattern and Rainfall Distribution - Next 10 Days
Rain and thunderstorms over the southeast will continue today and spread slowly into NSW, with the bulk of the rainfall increasing for northern and eastern VIC into southern and southeast NSW and the ACT by overnight and Tuesday as a wave forms on the trough. So cooler and cloudier for much of the southeast but if you are north and east of the cloud band, you will have warm weather continuing. A southeast change moves up the NSW coast on Tuesday into Wednesday bringing cooler air and showers following the cloud band. Fine weather generally returns to many locations from mid week. We will see a few clipper type fronts pass over southeast coastal areas with light rainfall but otherwise the wettest weather will be found over the northeast tropics which will be the area to watch. That is anticipated to send in a deep moisture plume through to the central and eastern interior over the weekend into next week with a widespread rainfall event still on the cards for ANZAC Day and beyond for large areas of the nation. Rainfall numbers will move around but the idea is unchanged from yesterday. The west looks to miss out on this event, but it is better news for friends in SA and into VIC and NSW where rainfall is required in Ag Areas. Some parts of northern QLD could also experience some flooding issues from this event in the medium term and that could also apply to the Outback.
12z Euro Precipitable Water Anomalies - Next 10 Days
This product shows the moisture drifting through the nation in the short term and marries well to the chart above, the three areas of moisture to watch will be over the northern tropics and how that descends south and west this weekend into next week, the easterly winds over NSW, how much moisture spreads inland over the course of the long weekend and the jet stream from WA over the southern states, does that also feed a trough inland over SA this weekend. Lots of weather to watch.
12z Euro Rainfall Accumulation - Next 10 days
Soaking rainfall for southeast areas today will spread into southern and southeast NSW and the ACT on Monday night through Tuesday bringing some areas 1 month's worth of rainfall. The rain clears out Wednesday with showers for the east coast of NSW. Then heavy rainfall emerges near FNQ on Wednesday with that persisting through to the weekend. The moisture is then dragged into a trough over inland Australia and rain and storms break out over ANZAC Day with some areas recording heavy falls and the Autumn Break over SA and into western NSW and VIC with follow up rain for the southeast thereafter. WA may see patchy falls from time to time but better rainfall opportunities return there from early May.
12z GFS Rainfall Accumulation - Next 10 days
The GFS is a little more aggressive on the rainfall unfolding through the southeast today and tomorrow with a low forming, bringing 1-2 months rainfall to some areas of southern NSW and northern and eastern VIC. The showers increase along the NSW coast while heavy rainfall develops over the FNQ coast. It is this moisture that then feeds into the trough deepening over the inland bringing widespread rain and thunderstorms from just after ANZAC Day and into the end of the month for the east. Rain patchy in the west, but this is subject to change next week depending on the timing of a front but certainly a drier airmass descending for northwest Australia.
12z CMC Rainfall Accumulation - Next 10 days
The CMC has the rainfall event in the east and southeast underway with a low likely to form today and that is what will increase rain and thunderstorms activity. Heavy moisture over the northeast tropics will then feed into the northeast winds aloft and into a trough sitting over inland Australia, the CMC placing that further west over the NT and SA into eastern WA with yet another upper trough. This sweeps east into the medium term.
12z Euro Rainfall Accumulation - Next 15 days
Extensive rain continues to build through the nation with a deep slow moving trough. This trough will meander through the east bringing 1-4 months worth of rainfall. You can see the tropical influence in the system from the north and that will need to be watched as this could bring flood risks to some parts of the inland given the airmass is very moist and temperatures for some areas are above average. More rainfall emerges through WA towards the first week of May.
12z GFS Rainfall Accumulation - Next 16 days
A lot of rainfall continues from day 10 through day 16 across the country with the main event in the south and east contracting through the southeast and clearing but additional moisture spreads throughout the north and west ahead of a cold front developing near WA and that looks to set up the next rainfall event into the first week of May. So as mentioned once the tap is turned on, it is turned on hard, given the SSTs are elevated around Australia.
I will have the next weather video this afternoon with your state based forecast information.