NSW - HEAVY RAINFALL OVER INLAND AREAS AND SHOWERS FOR THE COAST. LIGHTER RAIN MAKES THE SOUTHEAST.

The weather is very active in the west this evening leading to some places recording 3 months worth of rainfall in a sitting with pockets of flash flooding still likely overnight and into Wednesday morning.


A large band of rain will start to move further east across central portions of the state and then into the Great Dividing Range, but as it moves further east, the rainfall is forecast to become lighter and more patchy.


Showers across the east coast will be moderate and times and there may be some thunder developing with the taller showers as the trough approaches the coast. There will be no threat of severe weather for coastal areas at this time.


Moisture lingers over the state through Thursday and Friday with a warming airmass, some places could see temperatures back into the 30s. This will be in advance of another cold front that will move into the southeast by Friday. Ahead of it, the moisture should be lifted into a large mass of showers and thunderstorms during the late afternoon int he west and then spread eastwards during Saturday. Severe storms are possible with heavy rainfall and damaging winds.


Sunday, the rain and storms should be largely gone with a drier southwest to northwest flow to follow for inland areas and temperatures returning to seasonal. Frost risk remains near 0% chance for the period.


More rainfall exists next week in the form of another upper low and trough linking into moisture once again. Some of that could result in heavy rainfall returning next week. The above average rainfall will stay in place while we have above average moisture content floating about.


Lets take a look

FORECAST

Rainfall Next 10 Days

Rainfall is forecast to be fairly widespread through the coming week, but the falls will be variable in this current system overnight from one place to another, with the heaviest over the far western plains with the falls graduating lighter the further east you are. Along the east coast, scattered showers in onshore winds are forecast to continue for a number of days, some of these could be thundery. Another batch of showers and storms are likely to form along the next trough from Friday afternoon in the west with a moist airmass being lifted. The result will be a band of rain overnight into Saturday with severe storms on the leading edge of the cloud band in northern and northeast parts of the state Saturday afternoon. At this time, most of the rain should be gone by Sunday for inland areas with showers continuing for the coast. Next week, another batch of rain may develop over northern and western inland parts with showers along the coast as northeast winds feed another upper trough. The wet signal is set to persist beyond this period.

Southern and Southeast NSW and the ACT

Rainfall patchy with this first event but more widespread with the second event Friday into Saturday with locally heavy falls with storms. Rainfall numbers will fluctuate from one place to another. Further rainfall possible next week, but mainly north of the region.

Central NSW

Rainfall heaviest in the west tonight and during Wednesday before easing with the rain likely to increase again during Friday through the weekend. Another rainfall event is possible next week.

Northwest NSW

Rainfall eases from the west and north tonight with the bulk of the heavier rainfall forecast further to the south and east through the weekend with the secondary system. Could see some return rainfall through next week with another upper system.

Northeast NSW

The rainfall peaks with both systems over the west of the divide but we could see increasing showers for coastal areas in onshore winds. The rainfall will begin to increase next week if an upper trough lingers through the region leading to widespread showers and storms and possibly more inland rainfall from Monday or Tuesday.

Southwest NSW

Rainfall patchy tonight with rainfall clearing to the east then another batch of showers and storms due this weekend. Rainfall could be heavy at times between Broken Hill to Ivanhoe through to Cobar overnight and Wednesday morning, lighter elsewhere.

Thunderstorm Forecast Wednesday

Thunderstorms are forecast to develop along the trough during Wednesday afternoon and evening, especially if there is sufficient surface based instability. I am leaning to storms being mainly elevated within a rain band, with them producing heavy rainfall leading to flash flooding and some a damaging wind gust possible but very low.

Flash Flood Risk Wednesday

Flash flooding is forecast to persist overnight into Wednesday with some chance of areas recording 50mm/hr. Thunderstorms will drive the bulk of the flash flood risk but it will ease during the evening as the trough weakens.

Severe Weather Risk Friday-Sunday - Severe Storms

Another wave of severe weather is likely to emerge along a front running through the very moist and warm air over the eastern inland this weekend. Storms may turn severe with heavy rainfall and damaging winds the main concern and the focus generally on and west of the divide through central and northern areas.

MEDIUM TERM - May 4th- 11th 2022

Rainfall Anomalies

Rainfall signals remain above average for large areas of the north and east as well as pockets of the southeast and southern inland of the nation. Moisture persisting over the tropics likely being drawn into the jet stream will be lifted by areas of low pressure through the nation leading to above average rainfall. This pattern has been repeated time and time again this year and we are likely to see more of this occurring. A cloud band developing over northwest WA is possible if we see a tropical incursion approach the northwest of the country.

Temperature Anomalies

Not much change from yesterday with the cooler and drier air over the southwest leading to the below average temperature smear. Over the northern tropics, the above average humidity values will lead to above average temperatures during the days and nights with the above average rainfall signal. The east, higher humidity should keep things relatively seasonal, but wet and humid.

DATA - Refer to video for more information and the model comparison and context about all the forecast products you see from me.


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

More details in the video but we are staring down the current rainfall event in the east, a rainfall event to come over the weekend through southeast and eastern parts of the country with a cold front running into the moisture. Deep moisture to return next week lifting the chances of follow up rainfall for the southeast inland of QLD and northeast inland of NSW. More rainfall could emerge for SA with an upper system next week. The rainfall over the tropics also tending above normal for this time of year and that could run through the northwestern interior with above average rainfall chances as well. The southwest will be dealing with cold fronts and the possibility of moisture being drawn into the westerly wind belt from the Indian Ocean into the medium term.

00Z GFS - Precipitable Water Values - Next 2 Weeks

The values are anomalous over the east and that has lead to the excessive rainfall of recent days, but you can see the moisture easing in intensity over the next week. But further moisture may be drawn in from the northeast and north of the nation southwards next week into another upper level system. This could set the scene for widespread follow up rainfall. The tropics could be covered in very high moisture content into dry season leading to more above average rainfall. That moisture if it gets to the northwest of the country, could be propelled south and southeast through the nation via the jet stream.

00Z GFS - Rainfall Accumulation - Next 10 Days

Refer to the video for more context and analysis

00Z CMC - Rainfall Accumulation - Next 10 Days

Refer to the video for more context and analysis

00Z Euro - Rainfall Accumulation - Next 10 Days

Refer to the video for more context and analysis

00Z GFS - Rainfall Accumulation - Next 2 Weeks

Refer to the video for more context and analysis

A closer look in - the rainfall event on Friday through the weekend could be quite heavy and severe weather is quite possible once again for large areas of NSW. Note that heavy rainfall from this morning about the southeast and east coast is now gone which is the right call.

More coming up from 8am EST tomorrow. Have a great night.



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