NSW - EXTENSIVE RAIN AND THUNDERSTORMS NEXT 2 DAYS.

Well the rain has arrived for some in a big way today, with Narrendera picking up 50mm+ since 9am and a lot falling this morning causing flash flooding. This is a taste of what is to come with more rain and thunderstorms expected to spread through the state overnight and slowly contract east and north during Friday and into the weekend.


Unfortunately it is looking more likely that not that the rainfall is set to persist, even as we get warmer next week with persistent easterly winds.


Lets take a look at the latest details.

FORECAST

Rainfall Next 10 Days

Rainfall as we have seen today the falls are tropical with a very deep moisture layer. Where the storms form, they will drop a lot of water quickly and that is expected to continue overnight and through Thursday and Friday. Strong to severe storms are possible through much of the state during the coming 48hrs. The rain and thunderstorms begin to contract further to the northeast and east during the weekend but unlikely to clear. In fact it is likely we will see a resurgence of moisture through the easterly winds next week and further unsettled weather is expected to develop near a new trough that forms through the state, keeping the showers and thunderstorms going. We may lose the widespread rainfall, but the storms will dump a lot of rainfall where they form next week on current guide. Again keeping the forecasts broad and understand you could see more and less than what is advertised based on thunderstorm coverage. That is how it rolls.

Thunderstorm Forecast Thursday

Strong to severe storms are ongoing this afternoon and will continue tonight with the risk of heavy rainfall the main concern through much of the state. In the warmer sector over the far north some of the storms could drop large hail and damaging winds where there is greater lift, wind shear and instability with the upper low axis passing through. Storms have a high chance of producing 30-50mm where they form in an hour.

Flash Flood Risk Thursday

Heavy rainfall with thunderstorms have been observed throughout the state today with some locations recording flash flooding. This risk continues this evening and will persist into Thursday and peak during the afternoon and evening once again. Some areas could see 50mm/hr.

Damaging Winds Risk Thursday

Damaging winds are a moderate to high risk over the far north but more likely to be found in QLD where the instability and forcing is greater given the warmer airmass. The air is too rain cooled further south over much of the state.

Large Hail Risk Thursday

Similar to the damaging winds risk, you will find a low to moderate risk running along the northern inland up to the QLD border, but the greater risk of large hail will be found in QLD on Thursday afternoon.

Riverine Flood Risk Next 7 Days

Riverine flooding is still likely to develop, peak and persist through later this week and during the next 7 days with more rainfall most of the outlook.

DATA


00Z GFS- Surface Pressure Pattern and Rainfall Distribution - Next 16 Days

As you saw in the video with the GFS - there is good agreement across the board for the west to remain hot and dry and SA, once the low moves into NSW, will also turn dry through next week. The east and north continuing to see tropical rainfall, the wettest weather through NSW and QLD with renewed flooding. The rain eases across the weekend, though some modelling wants to keep the trough in place and spit the low off the coast, but one way or the other the lower confidence in forecasting is quite challenging to forecast, given the very soupy airmass that is in place and unable to exit, the rainfall could continue for some time to come beyond this severe weather event. So we must be prepared for that in the east and northeast.

00z GFS - Precipitable Water Values - Next 16Days

Very deep moisture profile to persist for a number of days, some respite for SA and VIC and possibly western and southern NSW through the weekend but the moisture comes right back to the southern and southeast areas of the nation. The west remains dry and hot with an easterly flow and seasonal weather for the tropics.

00z GFS - Rainfall Accumulation - Next 16 Days

More on this coming up at 9pm EDT.

A closer look in - it is a very concerning rainfall forecast for the southeast and east.

More on rainfall and the latest model data coming up after 9pm EDT. The Euro data is lagging tonight FYI.







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