FRIDAY MORNING WEATHER - TROUGH MOVES EAST WITH A DRIER AND WARM WEEKEND FOR MANY. WET UP NORTH

Updated: Mar 18

The weather is shifting eastwards over southern Australia after what has been a humid and unsettled week of weather. Just in time for the weekend, things are set to clear and warm up with above average temperatures expected. No surprise at the temperatures being above average as this was forecast last week right here.


In the east, a few showers and thunderstorms are forecast this weekend, but they will be isolated and most areas should escape mostly dry. The east coast could see a few showers over the weekend, starting out over the NSW coast and moving northwards Saturday afternoon and into QLD during Sunday and early next week.


Looking over northern Australia, also no surprise with the weather forecast to be unsettled, with the routine showers and thunderstorms over the Top End and Kimberly but with the MJO on the approach over the weekend and next week, there could be an increased coverage of rainfall through next week as the moisture and instability builds.


That moisture from the north and northwest looks to be fed into a jet stream that will be shifting south and becoming more wavy. This will allow for moisture to enter WA and spread through SA, the southern NT, VIC and NSW with a cloud band forming ahead of cooler air surging northwards behind frontal weather racing over the Bight.


Now there will likely be more cloud than rainfall with this cloud band through the week but if we see an upper trough developing later next week behind one of these systems racing south of the nation, we could have an inland rain event emerge with the moisture expected to be running west to east uninterrupted across the inland.


Later next week I am keeping an eye on the deepening moisture profile and the likelihood of tropical low formation increasing as well as we end the month and kick off April. This could set up a larger rainfall event across the nation as well.


The medium term has been very much looking volatile and offering a large amount of rainfall potential for western and southern parts of the nation but the confidence remains low at this time.


Lets take a look

FORECAST

Rainfall Next 10 Days - LOW CONFIDENCE FORECAST REMAINS

Once again the modelling supports low confidence rainfall forecasting so I am keeping the chart as broad as possible under such guidance. The weather looks to be wettest over the northern tropics with heavy falls developing as the MJO rotates closer to the northern region of the nation. The weather over the southwest and west of the nation may become showery with a front and prefrontal trough during the weekend with a burst of moderate rainfall. A front and trough rolling up the NSW coast may produce some showers, some of them moderate to heavy with thunder, this occurring over the weekend and again later next week. For the south of the nation, the weather is expected to remain fairly changeable with troughs passing through a fast flow pattern to the south of the country. This will lead to bursts of cloud and areas of rain and thunder about. But overall, these forecasts are a bit like chasing your tail, so just understand the forecast nationally is low confidence away from the tropics with the rainfall over the north looking likely to increase.

SOUTHERN ANNULAR MODE - SOUTHERN OCEAN - TURNING POSITIVE FOR A PERIOD - THE SECOND NEUTRAL PHASE IS THE ONE TO WATCH.

The volatility of the SAM is certainly being seen in the rainfall and temperature spread across the southern parts of the nation and also in relation to the fast flow westerly wind belt to the south of the country. So we saw the bottom of the negative phase yesterday but it was recorded at about 1-1.5 units closer to neutral than what was forecast. So this will mean that the frontal weather (we can see it at the moment) will remain further south, ridging will stay over the southern parts of the nation and the easterly winds will likely sink south from QLD with the SAM tending positive again. Now the positive phase next week looks to be strengthening and the models as mentioned in the video are starting to pick up on, placing heavier rainfall in the east of the nation as a result. But the SAM being so volatile at the moment means the forecast is poor.

MJO - TROPICS - MOVING INTO PHASE IN THE NEXT FORTNIGHT.

Seeing for the first time that the MJO is sweeping through from the Indian Ocean, over the Top End and then into the Western Pacific at pace which is the first time this particular model has shown this. That would see moisture rotate fairly quickly through the NT and into QLD. But when the MJO is in the Western Pacific, rainfall can increase quite dramatically for the NT and QLD and then run over the interior parts of QLD and through the eastern NT into northern NSW. So will watch that trend.

Thunderstorm Forecast Friday

Thunderstorms will continue to move eastwards through the southeast ahead of a trough that is being pushed along by a weak cold front. Another trough over eastern SA may see a few showers and thunderstorms return for parts of the Mid North, Flinders and into the eastern districts. Thunderstorms unlikely to be severe at this time. The risk simmers down at night. Over the north, we will see a southward sag of thunderstorms near a developing trough along the NT/WA border. Storms over the Top End and Kimberly may continue to be gusty with damaging winds. Heavy rainfall leading to flash flooding a small threat for the northern tropics.

Thunderstorm Forecast Saturday

Thunderstorms will appear mainly through northern parts of the nation, and be found across the tropics where storms could be gusty during the afternoon. There is a low chance of a few elevated thunderstorms for outback areas of NSW extending along a weak trough rolling up the NSW coast. No severe weather is expected at this time in the east.

Thunderstorm Forecast Sunday

Thunderstorms are forecast to develop further south over WA being drawn southwards by another wave of low pressure south of the state. Thunderstorms unlikely to be severe at this time. Thunderstorms scattered to numerous over the northern tropics with storms gusty at times with damaging winds a low risk. A cluster of thundery showers over the outback of QLD, again not likely to be severe.

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 Euro still showing a low confidence forecast with new features next week, the moisture streaming in from the Indian Ocean is there, but with the SAM more neutral than negative, the frontal weather is staying further south. There will be cloud bands traversing through southern Australia and over open water but whether they can produce significant amounts of rainfall remains to be seen, the Euro says most of that should fall offshore. The north unsettled with the wet weather continuing but not as heavy as other models. The remainder of the inland looks rain free which I am not buying at the moment, given the current state of the climate drivers. The MJO moving through the Indian Ocean would see troughs over in the west with moisture seeing at least, isolated showers and storms. With the SAM possibly turning positive later next week, the tropics will become wetter as will the weather over QLD and NSW, while under such guidance, the southern states would be drier. But at this time the confidence is poor.

12z Euro Precipitable Water Anomalies - Next 10 Days

The Euro had drier air dominating the south of the nation last night, and this morning it has more moisture back on the cards. When you see the Euro struggling with consistency from run to run, you know that the overall pattern is likely to change further. For the north, the showers and thunderstorms will continue and we will likely see widespread falls redevelop for north QLD where the trade winds freshen again. The MJO off the northwest of the nation will also drive showers and storms over northern WA with the moisture coming further south through the Pilbara and the chance of cloudbands developing over interior parts and about southern coastal areas with the moisture running through the northwest and westerly winds upstairs will see rainfall chances increase through the period.

12z Euro Rainfall Accumulation - Next 10 days

Refer to video for more information

12z GFS Rainfall Accumulation - Next 10 days

Refer to video for more information

12z CMC Rainfall Accumulation - Next 10 days

Refer to video for more information

12z Euro Rainfall Accumulation - Next 15 days

Refer to video for more information

12z GFS Rainfall Accumulation - Next 16 days

Refer to video for more information

Your 6 week outlook is coming up later this morning so take a look at that, will the wet signal continue on the modelling for the nation as we head into April and early May?


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