NSW - SHOWERS DEVELOPING FOR THE COAST, COLD STARTS CONTINUE INLAND BUT WARMER DAYS NEXT WEEK

The drier weather is forecast to be in place during the next week over inland parts of the state given the current synoptic scale, the large high is in force and set to lead to these cold nights and sunny days for the meantime. We should see the frost risk reduce as we go through the coming weekend as humid easterly winds begin to move into the state. It will be these easterly winds that provide the showery weather for the coast this weekend and into next week.


The tricky part of the forecast is the upper trough that is in force near SE QLD, the lower branch of this upper system is forecast to dip into NSW, but how far south it comes and how much that influences the shower coverage is yet to be determined at the moment. But overall, the weather is forecast to be damp along the coast, partly cloud over the inland with an isolated shower here or there but warming weather overall.


Next week, a series of cold fronts are forecast to push into the west of the nation with a deep moisture feed running through the jet stream. Rain is forecast to break out over much of WA next week and this could move into SA with a lower chance of the rainfall moving into the southeast. The first system should break down against the ridge. There is another system coming through WA that will have a better chance of bringing widespread rainfall to SA and then bring rainfall and cooler weather into the state.


Ahead of the rain, temperatures could get close to 30C in the far northwest and mid to high 20s elsewhere which is exceptional in itself. Cold air surging north into the Bight will set up a large thermal gradient which may support a thicker cloud band forming along the front as it works through. This is dependent upon the ridge to the east as well and whether it blocks the rain bearing systems out of the west.


So, as you can see there is a lot of moving pieces that will have to fall into place to bring the rainfall in earlier next week, but I do think we will see rain by the end of next week, and how heavy is up to how the system evolves out west and how quick the high moves away out east.


Let’s take a look

FORECAST

Rainfall Next 10 Days

Rainfall is forecast to be generally coastal for the next week with the showers developing later tonight along the coast and increasing during Friday and through the weekend with the heaviest of those falls probably north of Sydney. Lighter falls down to the Victorian coast. Showery weather is forecast to continue for the next week as the upper trough moves east of QLD but the high-pressure system over the southeast remains stationary, producing strong easterly winds and further wet weather. We are now starting to see some indications that showers and some thunderstorms could form through northern inland areas of the state. The risk is gradually increasing but remains uncertain and I have drawn in higher falls to account for the risk in the short term, so watch the forecasts in the coming days. The showers are forecast to decrease as we move into the middle of next week as the high weakens over the Tasman Sea. This will see warmer northwesterly winds develop and open the door for cold fronts to approach and drive moisture into the jet stream into the state from the west with showers and or patchy rain developing. The rainfall chances are forecast to increase later next week with the trough approaching with a front to follow bringing a colder shift and further rainfall across the state.

Widespread showers along the coast with moderate falls about, possibly heavy at times this weekend about the Northern Rivers as a trough moves through QLD. The showers continue into mid next week before conditions dry out as a westerly wind regime tries to return.

Frost Risk Forecast Friday and Saturday Mornings

The higher humidity that looks to be drawn across the southeast inland may offset the severity of frost across the regions during the morning and therefore mornings may not be as cold as what we saw today throughout the southeast. Frosts could be a little crunchier through the ACT and south to Cooma.

MEDIUM TERM

May 26th-June 10th 2022

Rainfall Anomalies

Rainfall anomalies are forecast to be quite elevated across the northwest of the nation and this spreading southeast via the jet stream in advance of an eastward moving long wave trough south of SA, this taking the wet weather throughout the southeast. Rainfall expectations at seasonal levels most elsewhere.

As we move into Winter, the rainfall should continue to evolve along the jet stream with the higher chance of above average rainfall through the northwest of the nation and extending southeast once again along the jet stream and into the southeast. Some well above average rainfall near the northwest coast of WA is likely. Some showery winds with above average falls for June over Cape York are possible.

Temperature Anomalies

The warm end to the month for the east and north extending to the east coast continue to strengthen on the signals. The colder bias over the northwest a very high chance of occurring under thick cloud and colder westerly winds and rainfall moving through. The amplification of the pattern representing the temperature spread across the nation, which could support severe weather across the country.

The cooler bias following the strong cold front and rainfall event moving through the southern third of the nation will send a large plume of southerly winds through the country during the first week of June, with further rainfall developing out west with another cold front, cooler than average weather continues for the western interior. Warmer weather with elevated humidity looks reasonable over the tropics.

DATA - Refer to the video for more context behind the forecasts and why models are all over the shop from run to run


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

The major weather systems to watch will be out over the west with a few fronts in the coming week, the major rainfall event along the east coast of QLD could produce locally heavy falls and thunderstorms. The high pressure over the southeast dominating the weather across the country with the system determining the influence frontal weather will be having on the nation as we move through the short and medium term. The latest GFS showing more bias for rainfall over the east coast and out west, but this morning it had a freer flowing pattern of rainfall moving from west to east across the country. That in itself shows you that using the broader data sets for forecasting is key. So don't rely on those apps, look at all broader information here to help guide your understanding.

00Z GFS - Precipitable Water Values - Next 2 Weeks

Moisture spread like this morning is largely unchanged compared to this morning, but as mentioned this morning, the placement of low pressure in relationship to that moisture determines where the rainfall evolves and becomes heavy. The higher moisture levels sit over the western parts of the nation and also across the east coast at the moment but I am not so sure on the deeper rainfall event along the east coast just yet and that moisture may end up staying further offshore with ridging holding out on that moisture being lifted into widespread falls. Moisture is still expected to spread across the country from west to east at this time.

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 - make sure you catch the rainfall update tonight to see the broader data sets. They offer more reliable information related to rainfall events and I can assure you this WILL CHANGE from the next run and tomorrow morning again. More clarity on rainfall will be found from Sunday. So, patience is required.

More coming up from 8pm EST with a look at the models and rainfall.





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