The showers and thunderstorms have begun to develop in random scattered pockets this afternoon in line with the trough moving in from SA and another trough moving west to merge with this feature overnight into Wednesday.
Showers increasing tonight and turning to areas of rain over the southern and southeast with local thunder. More robust thunderstorm activity is expected to developing over the western plains during Wednesday and this where we will see a high chance of severe weather across the region. This will add to the areas of rain across the state during Wednesday and Thursday.
More storms are forecast on Thursday and Friday with some severe.
Lets take a look
Rainfall for the coming 10 days
A lot is on the way with no real change in the guidance, but again these charts are somewhat difficult to draw with thunderstorms involved so your number will vary under such guidance. But widespread soaking rainfall over the course of 2-3 days can be expected across the eastern parts of the nation including much of NSW. The far west looking to get less rainfall but that is to be expected in the arid regions of the state. The weather will start to ease through the weekend before more rainfall redeveloping over the state later this week into early next week, mainly over southern areas.
Southern and Southeast NSW with the ACT
Northeast and Northern NSW
Thunderstorm Forecast Remainder of Tuesday
Thunderstorms are trending scattered as we go through the coming 12 hours as a trough begins to move in from the west and interacts with the deeper moisture that has been building through the eastern states. There have already been thunderstorms observed and they should continue to develop this evening and overnight.
Thunderstorm Forecast Wednesday
Thunderstorms are expected to increase in coverage to the west of a rain band that is to be placed from Melbourne to Canberra to Crookwell and through to about Mudgee. To the west of there, this is where will see the most robust thunderstorm activity develop during Wednesday. Storms could turn severe with all modes of severe weather possible. The far west should be in sinking drier air on the northwestern flank of the low pressure. Severe thunderstorms more likely in the central and northern parts of NSW but cannot be ruled out elsewhere.
Flash Flood Risk - Wednesday
The thunderstorm activity is expected to drive excessive rainfall rates of 30-50mm/hr through the inland of NSW, southern QLD and dipping into northeast VIC. Some areas could see inundation of low lying areas, especially areas over the southern inland of NSW and northeast of VIC where catchments are saturated.
Damaging Winds Risk - Wednesday
Damaging winds are a high risk on the trough at where the fresh thunderstorm activity fires during Wednesday afternoon and evening. If storms form an organised squall line, damaging winds are expected to be very high in this region but that risk is marginal at this time. Damaging winds are possible with any storms, but more likely during the afternoon and evening especially over central and northern areas and on the spine of the trough west of the rain band over southern NSW and northern VIC.
Large Hail Risk - Wednesday
Large hail becomes a significant risk during the afternoon and evening, especially over the northern inland of NSW and southern QLD where clearer skies to start the day will allow for the day time heating process to reach its maximum during the afternoon. Over the south the risk is diminished with cloud cover and areas of rain about limiting chances. Large hail risks will diminish in the evening.
There is a low end risk of an isolated tornado through northern NSW and southern QLD on Wednesday, but the risk may increase Thursday and Friday over the NE of NSW and SE of QLD with the trough moving east into a more favourable environment.
Riverine Flood Risk Wednesday-Saturday
The riverine flood risk is expected to ramp up as the rainfall increases from Wednesday evening through Thursday afternoon, that is where the most widespread rainfall is expected through the southeast. The coverage tends more scattered though with thunderstorms on Friday into Saturday, we could see another round of flash flooding risks under those storms, but the higher risk of riverine flooding is Wednesday PM through Thursday PM into Friday AM.
DATA - GFS can be found in the video for comparison
Euro 00z - Surface Pressure Pattern and Rainfall Distribution - Next 10 days
No real changes from this morning with widespread rainfall over the eastern states dominating with lighter falls back over SA for the coming days. Severe storms bringing wild weather to parts of NSW and QLD in particular. Flooding a concern under the current synoptic guide as discussed in the video for the east. QLD could see there best rainfall since July with the coverage of showers and thunderstorms over a number of days. For western parts of the nation a few showers and storms tomorrow ahead of a stronger front on Friday bringing more widespread rain and strong winds. That system will have a tough time up against the blocking pattern over in the east. It is still likely to bring scattered showers and gales to parts of SA and into VIC, but moisture is way more limited than with this current system. Another system should roll through the southwest of the nation early next week with more showers and storms, that system again tracking eastwards. Over the tropics the weather turning sultry and thundery, though an upper high may suppress activity at times next week.
Euro 00z - Precipitable Water Anomalies - Next 10 days
Again no real shift in the guidance with widespread rainfall developing out of a deep moisture layer that has built via easterly winds since Sunday and another port of mid and upper level moisture rushing in on the northern flank of low pressure in the Bight into the eastern states via the jet stream. Widespread rainfall is starting to occur over the eastern states as a result. The moisture content will stick around until southerly winds sweep the moisture out to sea. Another moisture surge comes south and southeast through the nation bringing another burst of rain to the west near the trough and front. The moisture thins out as it hits a brick wall over the east so rainfall coverage will not be as extensive due to this blocking pattern. Then another surge of moisture is anticipated over the southwest and west of the nation with another system next week, the tropics turn soupy and humid with increasing PW values and perhaps some of that drifting into WA sitting ready for the jet stream to pick up and lift southeast.
Euro 00z - Rainfall Accumulation - Next 10 days
Rainfall unchanged from last night and this morning, your number will vary under thunderstorm activity. The best of it falling over the east and southeas these next few days, before the focus shifts back to SWLD of WA Friday and then that sweeps through the southern states during the weekend and into early next week. Another system may bring more rainfall to the SWLD of WA continuing the trend of above average rainfall for the region this year. The northern tropics remain suppressed so if you are a fan of feeling like you are in Hades, well this weather will be for you.
A closer look in now.
GFS 00z - Rainfall Accumulation - Next 10 days
You can find out more about this chart in the video.
More details to come tonight from 9pm looking at the full model spread and an update on the severe weather potential, IF there are any changes ongoing.