Really not a huge change from overnight prognostics with the dry spell and warm spell for large parts of the nation continuing under a broad upper high and surface high in the Bight. Overall, the weather is looking very much as you would expect ahead of an Autumnal Break and I can still see one brewing beyond a moderate rainfall event for southern and southeast areas coming up next week.

The only wet weather of significance in the coming weekend can be found over the northern tropics where will be watching that deep moisture layer and a series of waves within an area of disturbed weather over the NT and QLD. We have already observed heavy falls in the past 3 days and more of that is to come.

A more substantial rainfall event for southeast SA and throughout VIC and into TAS is possible from Monday onwards and could linger through to the middle or latter part of next week. There is also the chance of some patchy light falls for much of inland WA with a weak trough about but the higher impact from this moisture plume looks to be found over the south or southeast. So some encouraging signs after a warm weekend for farmers to get their moisture levels they need for planting post Easter.

We are likely to continue seeing the Autumn Break in the charts in the medium term and this will play around for a while, but note that pinning that event down will not be possible until after Easter and until we get this rain event off the board in the southeast next week. Any follow up rainfall should be accompanied by a larger temperature shift making it a true Autumn Break.

This is what you would expect in response to the warm and dry spell under current climatic drivers so there should be no surprise in there being something of significance relating to rainfall and temperatures.


Rainfall Next 10 Days

Interesting signals on the modelling this morning, really starting to stand up the rain band from early next week for parts of SA through VIC and into NSW throughout the week, a slow moving cloud band being lifted by a series of waves to the southeast of the nation. There is every chance that this system could produce decent totals nearing 50mm in some areas of VIC and TAS if the systems are all in phase together. Across northern Australia, still showery with thunderstorms bringing heavy rainfall but seeing the depression risk fading a little, however widespread falls are still expected, especially along the eastern QLD coast north of Cairns with the trade winds. Rainfall over inland WA should be generally light and patchy but may linger most days this week with a cloud band that will meander along, feeding across the country and supporting the rainfall over the southeast. Into the medium term, we can still see the potential for an Autumn Break proper, but pinning it down in late April or into early May is the tricky part. I need to see it hold in the outlook and move into the short term forecast to be more confident in this actually occurring, but keep watch.

Thunderstorm Forecast Friday

Thunderstorms are generally expected over northern Australia once again in bands moving from east to west as we have seen in previous days. These will occur at all times of the day but more likely through the afternoon and evening. Chance of a dry thundery spell over parts of the southeast inland with a weak cloud band about.

Thunderstorm Forecast Saturday

Thunderstorms continue with above average rainfall chances for northern parts of the nation. Some of the storms could be severe about the Top End, especially in the east and around the Gulf Country with a deep low forming in a tropical wave.

Thunderstorm Forecast Sunday

Thunderstorms continue mainly about the Gulf Country of NT and QLD. Thunderstorms may be gusty at times. A weak middle level cloud band may form on Sunday afternoon in WA and graze southern SA and southwest VIC with the low chance of a thundery shower under it.

Thunderstorm Forecast Monday

Thunderstorms are forecast to emerge over the southeast with a cold front moving through Victoria and eastern Tasmania. Some of the storms could be gusty with moderate rainfall. Thunderstorms over the tropics forecast to contract further east but may increase in coverage if a tropical low forms near QLD. So this forecast is variable for northern areas.

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.

MEDIUM TERM - April 22nd-29th 2022

Moisture Watch Next Week

Getting fairly robust signals on the charts for moisture to stream across the country and to combine with the moisture moving in from the north and east, so the gradual increase in rainfall chances across the nation is likely through this period with the placement of low pressure the key to seeing who gets the most rainfall out of the sequence.

Rainfall Anomalies

Looking like many areas are leaning above average for rainfall chances but once again the placement of low pressure will dictate who gets the heaviest rainfall. The higher chances at this time is favouring the eastern inland once again, thanks to the positive SAM phase playing out. But a generally good chance exists over the west and north as well with seasonal weather for most elsewhere.

Temperature Anomalies

Temperatures will begin to ease from the high values through this period and if there is a major low pressure system that forms in the Bight, it is highly likely that temperatures will shift to below average values for many locations over western, southern and eastern Australia in response to a large scale low pressure system.

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 is fairly settled for the coming weekend, I think cloudy skies at times with high cloud shearing through the westerly winds aloft over southern Australia will be the only complications at times. The weather will be generally dry and mild to warm for the south, hot inland until about Monday. That is when we see rain developing under a more substantial cloud band that will set up over the southeast states more prominantly. Northern areas looking unsettled and active with humid air and low pressure wafting about but there too, the weather should begin to ease as high pressure and drier air builds over the region. A shift to easterly winds following the rainfall in the southeast later next week will see showers developing for the next long weekend over eastern Australia with the chance of that moisture then being propelled west through the eastern inland, laying in wait for a cold front and trough that is forecast to move over WA during the medium term. A convergence of moisture spreading from northeast, north and northwest is forecast to see widespread cloud and rainfall chances over the nation through ANZAC Day and beyond into early May.

12z Euro Precipitable Water Anomalies - Next 10 Days

The moisture content is easily identifiable via this product, you can see the moisture rushing into a front over the southeast during late Sunday and into Monday before deepening as low pressure forms Tuesday before it leaves by Wednesday or Thursday. Moisture over the northern tropics should linger into next week but the rainfall should begin to ease in coverage. Another surge of easterly winds forecast next week as high pressure builds in the Bight, is forecast to propel more moisture over the eastern inland and another surge of moisture from the Indian Ocean is likely, leading to more robust rainfall chances for the end of the month.

12z Euro Rainfall Accumulation - Next 10 days

The Euro suggesting a low pressure system forms on the trough and deepens the rain band over southeast Australia, heance the higher rainfall over eastern SA and into VIC and TAS. This is conditional and will continue to change so do not get too excited just yet. Would like to see the model hold onto this forecast a day out from the event kicking off to have more confidence. Rainfall over northern Australia will begin to ease and contract east next week. Showers developing along the east coast mid week with onshore winds. Patchy falls off and on this week over inland WA with a weak cloud band in place.

12z GFS Rainfall Accumulation - Next 10 days

Upper ridge over the southern and central interior over the nation is keeping things dry. Patchy rainfall developing under a large cloud band is expected to feature from inland WA through southern SA and more widespread falls developing over southern and eastern VIC and TAS. Onshore winds through the period bringing showers back to the east coast from about mid next week. Tropical weather is forecast to contract east through the Gulf and into the Coral Sea.

12z CMC Rainfall Accumulation - Next 10 days

Similar to the Euro, strengthens the rain band over the southeast mid week with a low forming on the trough and front before it moves eastwards. Light falls along the east coast generally. Showers, heavy at times over the north and patchy rainfall for southern SA and WA. Dry interior. That has been the theme with the strong upper ridge parked over Central Australia.

12z Euro Rainfall Accumulation - Next 15 days

Euro starting to follow the other models into the medium term picking up the heavier rainfall following up the system over the southeast in the short term, so watch this space. We could see some showery weather increasing over the east coast into the medium term as well with the trough developing along the coast and tropical weather is starting to ease.

12z GFS Rainfall Accumulation - Next 16 days

There is an autumn break in this package off the GFS and will have to watch carefully into the medium term. A lot of what you see falls in the day 8-16 range so not in the short term, which means we will have to keep it at low confidence forecasting for now. I think the model is picking up on the positive SAM phase hence the rainfall increasing over inland areas of the east. Not impossible, but certainly low confidence for now.

Have a great Friday and more details coming up this afternoon regarding rainfall over the southeast if it is warranted. Otherwise more tomorrow morning! Have a great long weekend and remain safe in you are travelling away.

232 views0 comments