NSW - FURTHER SEVERE STORMS EXPECTED IN THE COMING DAYS, SHOWERS FOR THE COAST.

The weather has been fairly active during the past 24 hours. Cobar recording 2 months worth of rainfall in less than 6 hours and more rainfall falling today. The scattered showers and thunderstorms over northern and central NSW continues to provide above average rainfall chances. The severe thunderstorm warnings continue for large areas tonight and again on Wednesday as an upper trough continues to move through slowly.


Along the coast, onshore east to northeast winds have been dragging in showers and thunderstorms. Some moderate falls have also been reported through the past day and more of that is to come as we track through the remainder of the week and into the weekend. To point out, models do not pick up what has happened in Wyong today, but my advice has been locally heavy rainfall with thunderstorms and uneven distribution in rainfall. 100mm in an hour is possible in some spots over the coming week on a daily occurrence.


The trough over the inland goes nowhere and the onshore wind regime will mean daily showers and thunderstorms are expected over inland areas. So a wet spell continues over the next week.


Lets take a look

FORECAST

Rainfall Next 10 Days

Rainfall remains widespread, heaviest along the coast but even for inland areas, 1-2 months worth of rainfall through the sequence cannot be ruled out. A broad and unstable airmass combined with a deep moisture profile over the region will see thick cloud cover and periods of rainfall, thunderstorms and severe weather potential. The weather over the far west should remain a lot drier west of the trough, but the further east you the weather will get wetter as you go. Some areas of the coast could see falls in excess of 300mm over this period but it is pointless drawing in where that could be. But the higher chance will be north of Sydney at this time.

NORTHERN INLAND AND NORTHEAST

Rainfall numbers continue to come up and there is evidence that numbers may come up further for the Northern Rivers and Mid North Coast and along the Gold Coast as well, with a trough amplifying in coming days.

SOUTHERN NSW AND ACT

Heavy rainfall still expected for the east coast extending inland to the GDR. The rainfall over the ACT and points west is more uneven in distribution, connected to thunderstorm activity but there may be more widespread rainfall developing early next week with a mid level trough approaching.

SOUTHWEST NSW

The rainfall still expected to taper off the further west you go but I am keeping an eye on a middle level disturbance that will approach from the west during the weekend and next week which may increase rainfall early next week.

CENTRAL WEST NSW

Rainfall numbers have come up through the region, with uneven distribution of rainfall expected with thunderstorms on and west of the GDR and more widespread falls from the coastal fringe through to the plains and the eastern slopes of the GDR.

NORTHWEST NSW

A very tight rainfall gradient has developed over the northwest overnight and with 40-70mm through parts of the Upper Western, this now allows for the flood risks to increase over the coming days with further rain and thunderstorms emerge. Drier weather expected along the SA border.

Thunderstorm Forecast Wednesday

Thunderstorms will continue tonight and through Wednesday with severe thunderstorms expected to continue for a fairly similar region as per today. Heavy rainfall leading to flash flooding is expected to be the main feature to watch with some areas possible seeing flash flooding multiple times during the coming 24hrs. Damaging winds remain a low risk as does large hail.

Flash Flood Risk Wednesday

Flash flooding remains a high risk over a broad area of the inland and central coastal areas, where a trough is triggering the most potent thunderstorm activity. Thunderstorms will become more widespread and the threat of flash flooding may drift further out to northern inland NSW and southern inland NSW.

Damaging Winds Wednesday

Damaging winds remains a low risk with the higher precipitation thunderstorms. But strong outflow winds cannot be ruled out as observed in the Upper Western overnight.

DATA - Refer to the video for the break down on the short and medium term weather for the region


00Z GFS - Surface Pressure Pattern and Rainfall Distribution - Next 2 Weeks

The GFS out most of the models this evening is struggling with the flow pattern. It is complex and the placement of the troughs in relation to the moisture will determine the rainfall coverage. Every run is still very much divergent from the previous and this will continue so I am keeping my assessment the same for the short term. For the medium term, the SAM remaining positive would keep the wet weather going over northern and eastern Australia, but if the SAM tends neutral, this will help extract moisture out of the northwest and drag it south and southeast through the nation and bring up rainfall chances for WA, SA and then VIC once again with troughs passing out of the west through the Bight and into the southeast. The east coast in the short term looks very wet, some of which has been experienced today. No time to play catch up in the forecasting game, use that as reference as that pattern will repeat many times through the wet season on the east coast with the waning La Nina.

00Z GFS - Precipitable Water Values - Next 2 Weeks

Moisture remains highest over the north and east through the bulk of this period but also starts to shift through central and southern Australia with some locations looking at copping some deeper moisture into the medium term. This will help to promote rainfall to expand across inland parts of the nation and developing over the SWLD as well as moisture is pulled into inland troughs, breaking the dry Mediterranean Summer.

00Z GFS - Rainfall Accumulation - Next 10 Days

Refer to video for further information

00Z CMC - Rainfall Accumulation - Next 10 Days

Refer to video for further information

00Z GFS - Rainfall Accumulation - Next 2 Weeks

Refer to video for further information

A closer look in - I suspect the GFS is off with the rainfall so refer to the models and rainfall outlook this evening from 9pm EDT.

More details coming up with the models and all things rainfall update later this evening.







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