NSW - SEVERE WEATHER ISSUES HEADLINE THE FORECASTS.

As outlined earlier today, the severe weather risks are looking to increase from tomorrow through the early weekend with a complex upper low and trough situation digging into moisture and leading to widespread rainfall and thunderstorm activity for inland areas. The far west once again through this sequence is likely to remain dry for now.


Lets get straight into it with the video and forecast charts below.

FORECAST

Rainfall Next 10 Days

Rainfall coverage is largely unchanged through the state but the location of the heavier rainfall is moving around and will continue to move around in line with the data sets becoming somewhat aligned. But if you are looking for full agreement with regards to this system, you are unlikely to get it, and rather we will be relying on real time observations to pin point the heaviest of the rainfall. Same can be said for thunderstorms over the inland areas with some areas likely to see some severe thunderstorms with heavy rainfall and large amounts of small hail a threat from these over Ag Areas so growers beware. The rainfall should gradually contract eastwards during the weekend and clear by Sunday as the airmass stablaises briefly ahead of the next front.

Southeast NSW Rainfall Next 10 Days

Heavy rainfall developing tomorrow afternoon and into Thursday poses the greatest threat from around East Gippsland through to about Ulladulla. From Thursday into Friday the heaviest of the rainfall will be on by but the showers will continue for coastal areas. The ACT seeing the bulk of the rainfall from Wednesday night through Friday morning and that includes much of the regions to the west, south and north of here too. The weather clearing the inland areas from Saturday as the trough weakens and dry weather Sunday before the next change.

Central West NSW Rainfall Next 10 Days

Rainfall could be heavy with thunderstorms over areas along the GDR through to areas westwards. From about Lithgow to Katoomba eastwards and southwards towards the Goulburn region and beyond, this is where the rainfall could be widespread and heavy leading to additional riverine flooding.

Northern NSW Rainfall Next 10 Days

Rainfall likely to be less intense over northern areas but with the showers and thunderstorms across the region, the distribution will be uneven but under storms heavy. The coastal areas and adjacent subtropical regions will see widespread showers and some of that could be heavy but at this time not as heavy as the southern areas. But keep watch on the showers and thunderstorms that will be approaching from the northeast this weekend with moisture spreading towards the coast from the weakening tropical low out to sea.

Thunderstorm Forecast Wednesday

Thunderstorms are forecast to emerge near the developing upper trough and low as it works into western NSW. The main area of thunderstorm activity will be located over the southern and central inland during the afternoon and possibly over the northern inland of NSW during the night hours.

Flash Flood Risk Thursday through Saturday

No real change to the guidance related to flash flooding but the focus has shifted a little further south from yesterday and that is good news for residents in the northeast districts for now but still keep watching. The rainfall rates could top 40-50mm an hour in some locations from Sydney southwards to the VIC border over the coming days. Moderate rainfall over inland areas over a long duration could see some low impact flash flooding develop too. Thunderstorms over interior parts of NSW will deliver a risk of flash flooding but the coverage of thunderstorms is scattered at best with many areas missing out on a storm. But be weather aware.

Riverine Flood Risk Thursday through Saturday The flood risk is growing for the Metropolitan coast southwards to the VIC border and for the adjacent coastal escarpment where falls in this zone could clear 100mm throughout the period widespread but spot falls throughout this zone could nudge 300mm. So this will once again see rivers rise through to moderate flood levels once again at least, possibly major flooding again.

Severe Weather Watch - Friday through Sunday

Deep moisture lurking offshore with the decaying and transitioning weak cyclone could bring a burst of moisture via easterly winds this weekend, and converge with activity over northern and northeast NSW leading to a slow moving area of heavy rainfall and thunder, that may lead to flash flooding. The risk is currently around 20% but worth mentioning and worth watching in coming days.

Frost Watch - Next Tuesday

Growers beware that the cold air following a strong cold front could bring the chance of light to moderate frost over parts of the southern and southeast inland of NSW and ACT. A sign of the times!

MEDIUM TERM FORECAST - April 12th-19th 2022

Moisture Spread

Moisture spread has not been changed from yesterday though just increasing the coverage of impact over northwest of Australia in relation to the tropical wave getting into the Indian Ocean. But overall, the airmass is very dry for large parts of the nation and rainfall coverage over the southeast during this period is expected to be light with high pressure in full force so not seeing much getting through that area of sinking air.

Rainfall Anomalies

A rather benign period of weather for much of the nation with ridging in control across southern parts. This is normal in relation to the seasonal transition across the country. The northern tropics could see some above average rainfall via the tropical wave passing through during this time, but higher chances are over the northern coastal areas. East coast could see another east coast trough between Brisbane and Newcastle but once again, the signals are poor but has been flagged in recent days.

Temperature Anomalies

Warmer than normal temperatures are still forecast for large areas of the nation's interior and this is thanks to ridging over much of the nation. Around the upper and surface high, onshore winds will provide cloud cover and seasonal to below average temperatures are forecast. Watching the westerly wind belt south of the nation which could send up colder air over the southeast which has been flagged but confidence is not as high on that idea.

DATA - Refer to the video for further information and it is critical to keep check of the data sets to understand where the next major weather events are emerging from outside of this period. It may be quiet now but I am all about preparation and ensuring that information is shared with you as soon as it is available.


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

More details can be found in the video for the short and medium term. It helps to put into context the parts of the outlook that carries higher confidence for certain areas over others.

00Z GFS - Precipitable Water Values - Next 2 Weeks

Moisture is set to deepen over the east with that persistent La Nina look to the distribution as well for the eastern states leading to the flood risk yet again. Watching the moisture offshore QLD as to whether that heads towards the SEQ coast this weekend. Otherwise the west and central parts of the nation extending into western NSW, VIC and QLD through to early next week under drier air for the most part with ridging. Then the fast flow pattern takes over and kicks out the humidity from the east early next week and fingers crossed a much drier picture develops for the east coast and rainfall and moisture returns to the southern coastal areas. We are still seeing the deepening moisture levels over northern Australia through the medium term as well taking us through Easter and into ANZAC Day.

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 GFS - Rainfall Accumulation - Next 2 Weeks

Refer to the video for more context and analysis

A closer look in - rainfall will be highly variable with storms over the inland of NSW and along the coast depending on where convergence zones set up in advance of the upper low drawing in that moisture from the northeast to easterly winds.


More coming up from 8am EST looking at the severe weather potential and a more detailed look at May 2022. Many will be watching closely as to whether the wet weather comes back to southern Australia and leaves the east.

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