MONDAY MORNING WEATHER - WET ALONG THE SOUTHWEST COAST OF WA. SHOWERS INCREASING OVER THE TROPICS.

Elsewhere, despite a few showers and maybe some thunder over the southeast today and possibly tomorrow, it is relatively quiet, in comparison to previous weeks of weather over the east and northeast. High pressure thankfully cutting off the moisture intrusion from the northwest and blocking the upper low from moving in from WA through SA and into the east, meaning that the wet weather will amplify and remain out west for the coming few days.


Meanwhile up north, the tropical weather is set to increase this week as a Rossby wave moves through the region bringing late season rainfall, some of that could be rather heavy at times. There is a low risk of low pressure forming along the wave and that could deepen into a cyclone if it forms over water. At this stage, the risk of that is very low and most models keep any circulation over land. Otherwise, the impact would be the same, with wet weather reaching very elevated levels over northern Australia.


The weather for southern and eastern areas of Australia through to Easter, generally dry away from coastal communities, where you will find the light showers and drizzle with onshore winds. The rainfall totals with any front over the weekend and into next week remaining light and patchy over the southeast and east coast.


For the inland of the nation, a dry 7 days on the way, however the moisture over northern and possibly northwest Australia could turn towards the south and then southeast with a cloud band possibly developing in response to the moisture being drawn into a jet stream and into troughs passing over Southern Australia. So that will be something to watch.


So we delay the higher rainfall chances over the course of the next week, Easter looks reasonable for those heading away for the camping weekend in the south and east but the northern tropics will be quite wet for Easter with conditions starting to ease leading into ANZAC Day.


That is when we start to see moisture spreading south and east through the nation and will wait and see who sits in the box seat for some Autumnal Rainfall. There have been rumblings of a break for SA and into VIC in the coming short and medium term, and one of these systems will stick.


Lets take a look.


FORECAST

Rainfall Next 10 Days

Rainfall is forecast to be fairly lean for inland areas of the nation with an upper high and drier air throughout the interior. The tropics is where the wettest weather in the nation is likely to be during the coming 10 days as a robust tropical wave moves through from east to west with this wave also expected to slow down, leading to very much above average rainfall. For the southwest of the nation, we have a deepening upper trough which is also leading to more widespread early wet season rainfall for the region. There could be some strong storms with hail and heavy rainfall over the coming day or two before the system weakens and shifts eastwards. For the remainder of southern Australia, conditions are forecast to be mostly fine. A few showers with weak fronts from time to time for coastal southeast areas with perhaps a clap of thunder. Over the east coast, showers are possible in onshore winds. The weather is forecast to remain near seasonal for many areas as we wait to see what the above average rainfall expectations this week over the north plays out for the remainder of the nation from Easter through to ANZAC Day.

SHORT TERM CLIMATE DRIVERS

Southern Annular Mode Next 2 Weeks - Volatile and low confidence in forecasting.

The SAM has turned back to a positive bias but overall with this forecast moving from neutral yesterday through to positive today, the neutral forecast is fair for now. But there will be impacts for the east coast and the eastern inland during the coming week or two regardless of the messy model output.

MJO Next 2 Weeks - No impact expected.

The MJO is in the region over the coming days but it is so far north, the impacts are expected to be minimal. But watch the easterly wave coming in over the course of this week, that will bring up the chances of rainfall.

THUNDERSTORM FORECAST THIS WEEK

Thunderstorm Forecast Monday

Thunderstorms are forecast to emerge near a weak trough over southeast NSW and the ACT but unlikely to be widespread or severe. Thunderstorms may become more numerous with a small hail risk over the southern WA coastline but severe weather not anticipated at this time. Storms over the northeast Top End later in the day but generally isolated coverage elsewhere.

Thunderstorm Forecast Tuesday

Thunderstorms are forecast to increase about the northeast Top End with thunderstorms expected to be gusty at times. Thunderstorms may develop over parts of the SA coast but these are unlikely to be severe and fairly isolated.

Thunderstorm Forecast Wednesday

Thunderstorms are forecast near an upper trough through the Bight and over Central SA with some of the storms expected to deliver light falls. Thunderstorms may develop about the Hunter and Upper Hunter with moderate falls. Storms increasing over the NT and FNQ coast with storms linked to a wave passing through from the east.

Thunderstorm Forecast Thursday

Thunderstorms are forecast to increase over the NT and QLD with some storms forecast to be heavy at times and gusty. Thunderstorms near an upper trough over the east of SA will likely to bring scattered thundery showers with mainly light falls. A few thunderstorms are possible over the Hunter with light to moderate falls.

Thunderstorm Forecast Friday

Thunderstorms near an upper trough over inland NSW and QLD will be mainly elevated and drop light rainfall if anything with drier low levels. Thunderstorms more frequent and heavy over the north with some storms severe with heavy rainfall and damaging winds possible. These may move into WA during the evening.

MEDIUM TERM - April 17th-24th 2022

Moisture Watch Next Week

Moisture spreading through northern Australia will work it's way into the Indian Ocean and then turn to the south and then southeast via the jet stream. The moisture will then have an opportunity of running into the southern ocean via cold fronts and troughs south of the nation, meaning that a large cloud band will set up along the thermal gradient and this is where we will see rain break out. This may reach southern SA towards SA and the southeast and east thereafter, if high pressure in the east allows.

Rainfall Anomalies

Rainfall anomalies all over the board in the outlook period which is par for the course this time of year. The tropics dictating the terms of rainfall spread through the short and medium and term. Above average rainfall to continue over northern Australia will spread southwest into WA. Moisture over the Indian Ocean will likely sweep into the jet stream and a cloud is forecast to form in response bringing rainfall to interior regions of the nation. How far east that comes is determined by high pressure over the east.

Temperature Anomalies

Temperatures are forecast to be above average for a fair chunk of inland Australia which is fair in relation to the placement of the upper ridge. Moisture rotating through northern Australia and over the Indian Ocean will lead to cloudy skies with scattered rainfall, some heavy. The southwest looking cooler than normal with persistent cloud cover and areas of rain with southerly winds. The east coast will see onshore southeast winds but rainfall should be light and more sunshine in between the cloud should see seasonal temperatures for now.

DATA - Refer to video for more information and the model comparison and context about all the forecast products you see from me.


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

The pattern looking relatively settled for most areas but the southwest of the nation looks to cop some heavy weather over the coming days with an upper low which will spin through the region for the coming 2 days before moving east. The tropics looking very active with a late season wave set to slowly move through, which could spin up into a low pressure system or cyclone. Some severe weather potential is possible about the Gulf Country or eastern Top End so will be watching. The wettest part of the nation looks to be northern parts of NT and QLD. For the east, low confidence forecasting, with modelling supporting a deepening trough this weekend over the southeast and east with showers increasing, but other models saying it will be dry. The SAM being negative one day and positive the next will mean modelling once becomes poor for western, southern and eastern Australia. High chance that inland areas will remain dry.

12z Euro Precipitable Water Anomalies - Next 10 Days

Moisture vales are somewhat mixed and not quite in phase with the low pressure rolling through southern Australia leading to lower rainfall totals and expectations away from the southwest of WA and tropics. The forecast however is low confidence. With the mixed signals from the SAM, the east coast rainfall could increase rapidly through the outlook period, especially if a positive SAM develops. The moisture via the tropics looks to have little impact. As mentioned last night here, the moisture could go 4 ways, and it is adopting a path that has little impact with the nation and is out of phase with troughs passing through the south of the country.


12z Euro Rainfall Accumulation - Next 10 days

Refer to video for more information

12z GFS Rainfall Accumulation - Next 10 days

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12z CMC Rainfall Accumulation - Next 10 days

Refer to video for more information

12z Euro Rainfall Accumulation - Next 15 days

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12z GFS Rainfall Accumulation - Next 16 days

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More coming up today on the latest on whether La Nina will leave at all through the cool season and is she set to return for 2022/23.