NSW - RAINFALL DEVELOPING TONIGHT FROM THE WEST AND SPREADS EAST TUESDAY

The process of a rain band forming is under way as the front interacts with moisture streaming down from the northwest and being lifted by a cold front. Scattered showers have become more widespread this afternoon over eastern SA as the front slowly moves into the moisture plume. A few thunderstorms have also gotten underway near the cold front.


Satellite Imagery

Cloud is increasing from the west with the shower coverage becoming more widespread as the front moves into the moisture coming in from the northwest. The sunny skies will cloud over through inland NSW this afternoon. The showers will increase over the northern inland tonight and western inland this afternoon. All of this merging to bring areas of rain and a few storms to the plains and GDR overnight into Tuesday morning, light and patchy falls for the coast. Showers to follow over the inland on Tuesday possibly some small hail and thunder.


All that mess out west will spill through western and southern NSW tonight.


A separate area of convection has formed this afternoon and light showers have been showing up on radar, not a lot so far, but as the front begins to move into the eastern inland, the precipitation coverage will increase.


Thunderstorms are still possible over the northern inland of NSW spreading towards the GDR overnight and coastal areas tomorrow morning, but isolated under the mass of cloud and rainfall. Damaging winds are a small chance overnight.


There will a chance of thunderstorms tomorrow over the northeast and southern inland of NSW with a hail risk for those along the VIC border. But the air is drier so the coverage of showers less than previous weeks.


Thunderstorm Forecast for Tuesday

Thunderstorms will begin to clear through from inland NSW and QLD towards the coast and the risk resolving by afternoon. Thunderstorms mainly elevated, non severe and containing perhaps gusty winds and moderate rainfall. A colder airmass in southwest winds may begin to produce showers with some of the taller showers developing into pulse storms with brief small hail and gusty winds, most likely during the peak of the day time heating process. The risk also diminishes during the evening and contracts east.

Hail Risk Forecast - Tuesday

Small hail is possible with showers and thunderstorms through the southern inland of NSW and more likely over VIC as the colder air mass moves through during Tuesday, it clears east during Tuesday night.

State of Play for the coming 12-18hrs.

The inclement weather has moved from WA through to the east with a high nosing in and pushing the long wave trough over SA today and that will then be through to east of NSW by Wednesday with a colder airflow to develop over the southeast and eastern inland.

For the remainder of the state, the weather becomes colder from the south and west during Tuesday with a southwesterly airstream developing and this then moving north during Tuesday afternoon and into Wednesday.


Inland areas will slowly dry out with the skies turning clearer from northwest to southeast as the weak ridge of high pressure moves in. That will then strengthen on approach to the east this weekend, so after a gloomy week, the weather will improve for southern inland areas by the weekend.


Dry weather to follow through early next week with some areas likely to see above average temperatures developing. The next lot of fronts approaching by this time next week at the earliest. But it is a low confidence forecast.


Let's look at modelling


00Z GFS Surface Pressure Pattern for the coming 16 days

The fast flow pattern finally starting to slow down with the last passage of low pressure coming through the southeast states tonight with rain and storms breaking out over the eastern inland of NSW through southern QLD and showery weather over southern SA moving into VIC and TAS. The hot weather over the northern parts of the nation beginning to move north over the coming days, back to the tropics. High pressure moving in over southern WA will finally bring brighter weather for the southern states, a slow clearing process for southern inland NSW and the southeast generally, but the weekend it will be drier. This weekend into next week we will be watching the moisture build over QLD and the next frontal passages come through WA, and whether they can stay in tact to bring more rainfall to the eastern states.

00z GFS Rainfall for the coming 10 days

Rainfall for the coming 10 days is primarily over the next 2 days for NSW with the bulk of it falling Tuesday before clearing the north later tomorrow and the southern inland during Wednesday. The weather greatly improving by Friday, once the moisture from the southwest to westerly flow modifies and mixes out. That will set the stage for a lovely weekend of weather for the state. The next chance of rainfall comes with frontal weather approaching next week, but that is low confidence forecasting at this time.

00z GFS Precipitable Water Anomalies next 16 days

The elevated PW values are still expected to move east and northeast over the coming days before drier air takes over. The southerly surge will clear the eastern inland by mid week, though the weather is expected to turn soupy over the northern tropics, thanks to the east to northeast winds returning this weekend. Onshore winds will develop over parts of the east coast with the chance of showers developing, but that moisture coming inland a little bit in recent runs. So we will watch that. The next major wave of westerly winds will have a moisture in feed from the tropical northwest Indian Ocean which will bring a band of rain through WA this weekend. The latest guidance showing a stronger set of fronts, but again low confidence in this forecast. The moisture levels in the medium term are still elevated so rainfall chances look on track to increase by mid month for inland Australia.

00z Euro Surface Pressure Pattern for the coming 10 days

The frontal passage is set to pass through the southeast overnight and through Tuesday introducing that rainfall tonight from west to east. The rainfall should clear through NSW and VIC fairly quickly and northern parts of NSW and QLD during the afternoon. A drier and more stable airmass will follow for QLD and northern NSW and that drier airmass slowly clearing out the remainder of inland NSW and VIC, SA and TAS by later this week. Once we get to the weekend the east is settled under high pressure. BUT the model madness continues with low confidence forecasting next week, Euro tonight showing a unstable and moist northwest flow developing mid next week with rainfall chances coming up potentially for inland Australia spreading east.

00z Euro Rainfall for the coming 10 days

Rainfall largely set to fall over the southern and eastern states during the coming 2-3 days before the showery coverage over the inland of NSW and VIC clears from mid week and then the coastal areas should see a reprieve from Friday as the airmass dries out. The weather is expected to remain dry and settled this weekend for much of the east and southeast. Next week the weather may turn warmer than normal ahead of another potential rainfall event, but it is a very low confidence forecast at this time for the southern states.

00z Euro Precipitable Water Values next 10 days

You can track that moisture through tonight over eastern areas contracting north and east with the passage of the front. The drier colder southwesterly change will come through, but then shallow moisture will return to coastal areas and inland areas west of the divide as high pressure ridges in with low cloud and light showers continuing to about Thursday. The east coast and northern inland parts of NSW should clear quicker. Then dry weather over the weekend with stable air. Next week, watch that elevated moisture plume coming down ahead of the front approaching from WA. That could see rainfall break out from central Australia through SA and into western NSW and VIC later next week. It could also get to QLD with onshore winds and showers, also allowing moisture from the east coast to be transported west. So all of a sudden plenty to watch.

Rainfall for the next 10 days

Rainfall is largely unchanged despite the wave of weather moving through currently. I have taken numbers down over SA and that will continue to progress east overnight so expect this chart to look a little more bare than today. However there could be something stirring mid next week, if the Euro is correct, there may be more widespread rainfall expected to develop. Inland areas should see a dry 4-5 days from mid week. The coast will see some rainfall tomorrow but nothing more than 5mm, and essentially 1-2mm for the southeast inland east of the divide as the dry season continues.

More weather details to come Tuesday including the next state based climate outlooks for the month of August, and pinning down the short term forecasting is tricky so I will be interested to see the new data in the morning.





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