NSW - RAIN DEVELOPING SATURDAY AND IT IS STICKING AROUND

Boy oh boy the past few days of modelling have been wild and I don't think I have ever seen it as volatile, but that is spring time, hence why I always say just hold the line and make sure you keep up to date with the forecasts. It will change.


We are still expecting rain over the central and northern inland of NSW during Saturday and Sunday then clearing eastwards Monday. The heaviest falls now located further north as a ridge to the south bumps the low further not, the ridge firmer not as flat, not allowing the system to dive southeast.


Renewed flooding is possible as mentioned over a wide area, but some catchments may be spared so keep up to date.


Southern areas bordering VIC and now the ACT may end up dry! Quite a remarkable turnaround in guidance but keep watching trends.


Now next week we are looking at more significant rainfall and with SAM remaining positive, that will encourage further rain and thunderstorms. A system with major rainfall status will emerge at some stage in this pattern, it is not a matter of IF but WHEN. So lets take a look at the short and medium term

FORECAST

Rainfall Next 10 Days

Rainfall is expected to be widespread but the shifting in modelling has been quite remarkable and will continue to mean the forecast remains low confidence. However if you are living through the flood zones expect further rainfall and river rises and stay up to date. Main rainfall comes through central and northern NSW over the weekend with the southern districts now looking drier. The rain turns back to showers early next week with afternoon thunder. Then the secondary feature rolls in from the west with further rain and thunderstorms, merging with the moisture left over from the first feature leading to more widespread rainfall, all of a sudden this system could drop another month's worth of rainfall for some locations over the inland. Coastal areas could see a very soggy spell with widespread showers developing once again from the weekend through all of the outlook with heavy falls developing. Because of the low confidence in rainfall I am now reverting to the broader charts again and I will update this again on Saturday morning.

Thunderstorm Forecast Saturday

Thunderstorms likely to develop in the warm and unstable airmass north and east of a trough and near a developing low. Some storms could be strong with gusty winds and heavy rainfall over the northeast with large hail a low risk at this time.

Flash Flood Risk Saturday

Thunderstorms carry a moderate chance of flash flooding on Saturday with the risk translating east through the day. Thunderstorms training over the same area for a period of time from west to east may also bring flash flooding.

Damaging Winds Risk

Damaging winds also a chance with thunderstorms during the afternoon and evening, with the strong jet aloft being mixed to the surface with heavier storms. You will likely find this on the northern flank of a cloud band over southern and central areas.

Flood Risk This Weekend

This chart just keeps bouncing around, it really is quite a remarkable shift in the modelling however be aware of heavier rainfall once again over inland areas and stay up to date.

DATA


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

The pattern is very dynamic - more details can be found in the video to cut down read time.

00Z GFS - Precipitable Water Anomalies - Next 16 Days

The humidity is deeper as we go through this period and will lead to widespread rainfall and thunderstorms. Flood risks increase this weekend and goes hand in hand with the moisture deepening over the northern and eastern parts of the nation

00Z GFS - Precipitable Water Values - Next 16 Days

The values consistently around the 30-50mm values indicates a prolonged period of above average rainfall and high humidity for the east. Southern and southeast areas may get a break but now we are seeing moisture surging into WA as well with above average rainfall chances.

00Z GFS - Rainfall Accumulation - Next 16 Days

Refer to video for more

A closer look in - the low confidence rainfall forecasts continue due to the complex and dynamic flow.

More details on all things rainfall after 9pm EDT tonight. Stay weather aware.

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