The pattern is becoming stagnant and slow moving in the east, a deep layer of moisture has begun to sweep south from the north and east, meeting the shapening trough and as a result, showers and thunderstorms have continued to break out in response.
The weather will turn sharply wet this afternoon with scattered storms about eastern SA, northern VIC, much of NSW and QLD extending back into the NT with that storm activity the start of the major rainfall event as the clusters of storms merge to produce thundery areas of rain. Heavy rainfall has been observed overnight in storms through western VIC and eastern SA through to western NSW and this is a signal of what is to come.
Further east, the rain will increase for eastern NSW and QLD but at this time the heaviest of the rainfall looks to be on and west of the divide with this lead feature until Friday.
The low will move into NSW tonight and move slowly along the VIC border before one part leaves the southeast of the nation later tomorrow, but the upper low will remain over NSW keeping the rainfall going. Widespread heavy rainfall on Thursday into Friday is the rain of concern with flood risks increasing for southern and southeast NSW and renewed flooding for central and northern NSW.
The heavy rain and storms along a trough will move through QLD over the course of the next few days but the true focus of torrential rainfall becomes clearer over the weekend if not next week as the trough deepens and heads back west and then south into NSW. This will likely spark another round of heavy rainfall and thunderstorms.
SA and points are expected to turn dry this Friday with windy weather, hot in the west and seasonal over the tropics. The weather rinse and repeat over the these regions into next week.
Lets take a look - apologies for you guys under boring weather in the west - it is a run of hot and dry weather which I know many in the east would love right now! That easy forecast compared to the drama in the east means there is not a lot to discuss just yet.
Rainfall Next 10 Days
Rainfall is extensive and heavy as mentioned in the video. These numbers will continue to bounce around so read as a guide and know that thunderstorms will deliver heavier rainfall in locations that may be expecting 10-20mm and areas expecting 100-130mm could see only 60mm. I cannot stress the main concern is around flooding through catchments, not just properties, so look at the catchments in the east for rainfall totals, not just your place. We are beyond that hyperlocal forecasts in these situations over the course of the next 10 days. Otherwise the west is dry and hot with no rainfall expected and the tropics your hit and miss showers and storms continue.
Thunderstorm Forecast Wednesday
Thunderstorms are ongoing from overnight and are currently moving through VIC and NSW and these are elevated and non severe at this time. The main storm action will erupt through eastern SA, western QLD, the NT and through northwest NSW and move south and east through the day into central and southern NSW with heavy rainfall the main risks. The heavy rainfall rates could exceed 60mm/hr. Damaging winds are also possible but not a strong chance in NSW but more likely in QLD. There is very little risk of large hail with atmosphere saturated but we could see some hail near the developing low in SA.
Thunderstorm Forecast Thursday
Thunderstorms are expected to be widespread through the east and north with the risk of severe thunderstorms, producing heavy rainfall leading to dangerous flash flooding and damaging winds, mainly over NSW, the ACT and QLD. The tropics will see widespread showers and thunderstorms with some damaging winds and heavy rainfall.
Thunderstorm Forecast Friday
Thunderstorms beginning to shift north and east as a drier southeast to southerly change moves through the southeast states. Ahead of the wind shift, the deep moisture is still in place with a risk of flash flooding and riverine flooding with the heavy thunderstorms moving over the region. Storms over the tropics also severe about the western Top End with damaging winds and heavy rainfall. This could spread into the Kimberly as well.
12Z Euro - Surface Pressure Pattern and Rainfall Distribution - Next 10 Days
No change in the pattern but the low is complex, broad and with multiple centres on it's journey from SA through NSW and QLD, which means that the rainfall will continue to chop and change, and as mentioned multiple times this week and with the previous system, all you need is a wiggle 20km north or south in the placement of the system and your numbers will change. What carries high confidence is the drier and hotter weather out west with a persistent easterly wind through the weekend and into next week. The tropics also unsettled with routine weather. The tricky forecast continues for the east next week with mixed odds on whether the new trough next week amplifies over NSW and QLD and taps into lingering moisture to produce more widespread rain and thunderstorms from this time next week. That will be updated in the medium term forecast later this morning.
12Z Euro - Precipitable Water Values - Next 10 Days
No change in the guidance but this is a great product to track the low pressure system as it evolves over SA, QLD and then into NSW with the system looking more complex than previous days, which means the rainfall forecasts are again likely to be volatile in the next day or two, so the forecasts remain low confidence on picking how heavy your rainfall will be, but it is looking like widespread rainfall and high humidity none the less with this feature increasing flood risks. The west sees a nice dry surge remain in place and easterly winds running over the continent also bringing dry and settled weather with hot conditions, that may drift eastwards next week to SA and VIC. The north, remains soupy and unsettled with tropical waves moving more freely from east to west over the northern parts of the nation, that may be drawn south and southeast into the nation into December.
12Z GFS - Rainfall Accumulation - Next 10 Days
More details on these can be found in the video.
12Z CMC - Rainfall Accumulation - Next 10 Days
12Z Euro - Rainfall Accumulation - Next 10 Days
More details on the severe weather potential throughout the east and southeast and the medium term forecast which offers some decent chance of further rainfall but perhaps, we may be seeing a few drier days creeping into NSW and western QLD. We will see.