The weather is active east of the Goyder's Line through SA with lighter falls to the west, the great dividing line of weather showing itself well in the forecast packages this week.

A warm few days is on the way too with a northwest to northerly flow emerging today and freshening tomorrow and strengthening Friday sending in a nice warm up ahead of a colder westerly change on Friday afternoon.

It will be along that front we see a band of showers and thunderstorms developing which should commence on the eastern EP and then become more widespread on or to the east of Adelaide before becoming extensive along the VIC and NSW border. This is where the heaviest of the rainfall is expected at this time.

During the weekend, conditions should return dry for much of the state and much cooler too with a west to southwest flow easing. The lingering moisture plume via the jet stream may kick off a few showers in the northeast but overall it is looking much drier and cooler for most.

Next week the weather starts out dry with a high nearby, but the next front racing through WA during Tuesday will surge into the Bight and this system could then begin to turn a little more northeast and bring a band of rain through southern and southeast areas during this time next week.

Some of the modelling has been more amplified than what current models are suggesting. So watch this feature closely in the coming days and I think we will have a better handle on that during the weekend.

Lets take a look


Rainfall Next 10 Days

Rainfall is forecast to be generally patchy and uneven over the state now, we are seeing that trend of pushing the system through a little quicker with more widespread rainfall expected to be observed east of the state, where the deeper moisture and better atmospheric dynamics will be located. Now in saying that, the air along the front is unstable and that should kick off a band of showers and storms in itself, likely east of Adelaide is where you will find the heavier rainfall. Drier weather returns for much of the weekend and into next week with a high pressure ridge. The next change is due to approach during Tuesday or Wednesday next week. A band of rain or showers may develop over southern Ag areas with moderate falls possible for the southeast but the confidence is not especially high. I have mentioned above that modelling has been supportive of more widespread rainfall that is being forecast here for this event. So more details to come on that.

You can see the better rainfall is further to the east with this event. But watch the rainfall over the course of next week which is not quite drawn in here due to low confidence.

Severe Weather Watch

Severe thunderstorms are possible along a change on Friday afternoon in the east and northeast but the better coverage of thunderstorms and severe weather will be further east at this time in NSW and VIC.

MEDIUM TERM - May 5th- 12th 2022

Rainfall Anomalies

The rainfall bias has shifted to the east in recent broader guidance, given that we are seeing more drier and cooler air sweep the country. I am suggesting rainfall will be more aggressive over northern and eastern areas of the nation with the SAM tending back positive and with the lingering moisture courtesy of the lingering La Nina, the potential for a rainband to form in the north and east is quite likely. The west and remainder of the south seeing seasonal rainfall expectations. But the door is open for moisture to sweep south and southwest into these areas as well so watch closely.

Temperature Anomalies

A much colder signal has been triggered on the models with all in agreement we could see some quite fresh air being transported behind a strong cold front mid next week leading to the first chance of snowfalls on the mainland and the chance of frost for southern Ag areas of the nation so growers beware. The only thing offsetting the risk of severe frosts is that the SSTs around the nation are above normal and we do have a positive SAM phase unfolding in the east so while watching trends closely, there may be the chance some frost issues we could be talking about in around a week's time for the medium term.

DATA - Refer to the video for further information and it is critical to keep check of the data sets to understand where the next major weather events are emerging from outside of this period. It may be quiet now but I am all about preparation and ensuring that information is shared with you as soon as it is available.

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

The pattern remains largely unchanged for the nation as we track the next major weather maker into the southeast and east this weekend. That could produce severe weather as outlined in the video. The trough may linger over eastern areas of the nation and combine with moisture in the onshore winds to see more rain develop for eastern QLD and NSW. The northern tropics are forecast to be unsettled and more humid than normal with the risk of showers and thunderstorms developing most afternoons. Over southern parts of WA, the next front comes through tomorrow but the next major front is forecast on Monday night through Tuesday bringing that colder shift to the southwest with drier air. The front and trough then run across the southern parts of the country with the chance of widespread showers and gusty winds coming into SA mid next week and then over the southeast and eastern parts of the country. This system could form into a major low pressure system over southern and southeast/east areas of the country but the forecast confidence is low. Also watching the moisture in the tropics into the medium term which could turn south and southeast through the nation lifting rainfall chances once again through the medium term with higher humidity also spreading south and east. The weather supportive of below average day time temperatures for the west, warmer over the north.

00Z GFS - Precipitable Water Values - Next 2 Weeks

Moisture remains deep and elevated over the east hence the cold rain today for many and really the cold rainy weather since about Saturday. The first system is weakening but leaves a trail of moisture behind it, laying in wait for the next system to slam into it on Friday leading to more widespread rainfall. Some locally heavy rainfall is possible as is some flooding for parts of the southeast if widespread heavy rainfall eventuates. The drier southerly flow will move through southern parts of the nation but struggle to push further north. The northern tropics and much of the east will remain in humid air through much of the outlook with onshore winds via the new high ridging through southern areas, and the deeper northeast flow still bringing in above average moisture values over tropical areas. Watching the Indian Ocean into the medium term as outlined today, this could lead to more robust rainfall developing through the medium term.

00Z GFS - Rainfall Accumulation - Next 10 Days

Refer to the video for more context and analysis

00Z CMC - Rainfall Accumulation - Next 10 Days

Refer to the video for more context and analysis

00Z Euro- Rainfall Accumulation - Next 10 Days

Refer to the video for more context and analysis

00Z GFS - Rainfall Accumulation - Next 2 Weeks

Refer to the video for more context and analysis

A closer look in - this forecast output from the GFS will change dramatically in the coming days. Rely on the next 3 days of data probably being something worth betting on, the rest is looking low confidence.

The next update is due out at 8am EST on Thursday. Have a great evening.

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