NSW - PATCHY RAINFALL ABOUT THE INLAND TONIGHT WILL CLEAR EAST TUESDAY. DRY FOR MUCH OF THE WEEK.

OVERVIEW

A band of cloud has moved into the west of the state this afternoon and while it has been mostly sunny further north and east today, tomorrow is set to be cloudy with areas of mostly light rainfall pushing eastwards.


A cooler airmass will follow the rain into the south tomorrow night with a shower or two developing in the unstable air before conditions clear off during Wednesday.


There is the risk of severe frost and freeze conditions developing later this week and into the weekend under high pressure pushing into the east of the state from Saturday.


SHORT TERM

So this week is relatively quiet in comparison to previous weeks as ridging holds firm, knocking out the full impacts of the developing cloud across the state this evening and into Tuesday. A colder airmass moving in from Tuesday and another shot of cold air surging northwards from Thursday will become trapped under a new centre of high pressure developing over SA that will settle in from Friday.


Cold mornings with severe frost and freeze conditions will feature this weekend but lovely days to follow.


A series of stronger cold fronts and low pressure troughs will begin to move into the south and southeast from Sunday and we will see the daytime temperatures rise markedly in northwest winds. Showers are likely to break out in advance of the frontal weather from either late Sunday into early next week with those on and west of the divide looking wettest.


A more active week of weather next week can be expected with further moisture and rainfall spreading throughout the inland, once again favouring those on and west of the divide as is typical for this time of year. Rainfall intensity will become clearer as we move through this week.


LONG TERM/AREAS TO WATCH

A fairly active pattern looks to establish from the west during next week, with a deep moisture profile extending from the northwest of the nation and also evidence now that moisture may also run over northern and northeastern Australia and spreading southwards into the southern and eastern inland.


The location of troughs and frontal weather in relation to the moisture will remain of interest. That determines where the best of the rainfall develops and where it is most persistent.


Severe weather potential is increasing for areas over SWLD of WA and possibly for southern and southeastern areas of the nation with the higher chances of low pressure running through the westerly wind belt.


Humidity values are also expected to increase over northern Australia with the upper ridge remaining in place but, the feature could weaken and this may open the door for more cloud and the chance of showers returning as well to northern and interior parts of the nation.


FORECAST VIDEO PM - MONDAY 25TH JULY 2022

FORECAST

Rainfall Next 10 Days

Not a whole lot of rainfall is expected through this week, patchy falls on and west of the divide tonight with up to 5mm possible. A few showers may get onto the east coast and through the northern inland but the coverage of rainfall is expected to remain widely scattered. Showers may return to southern areas on Tuesday and Thursday with colder air drifting through but once again mainly light falls with a dry airmass and westerly flow. A new wave of rainfall chances approaches from later in the weekend and persists through most of next week and while the rainfall coverage is expected to be located on and to the west of the divide, the chances of rainfall increasing over the plains is expected as well as heavy falls developing over much of VIC and points back to the west of the ACT through Alpine areas. Severe weather is also possible.

A closer look at the rainfall spread throughout the southeast and southern inland, you can see the development of the westerly wind regime taking over the nation’s synoptic flow pattern resulting in more seasonal rainfall expectations being achieved throughout the short and medium range.

Severe Weather Watch - Frost Becoming Severe Friday through Sunday.

The risk of severe weather via frost damage is running high later this week as cold air following a cold front during Thursday with a developing southerly flow projecting the colder air into the southern and southeast then eastern inland. A cold set of nights under sinking air motion, clear skies and light winds will allow the ground too effectively and this leading to another round of severe frost and freeze conditions. Some areas could see damage from the frosty conditions to sensitive plants and crops exposed to these nasty cold nights. Conditions will be clear and sunny through the daytime and above average temperatures possible by Sunday.

MEDIUM TERM

July 31st - August 15th, 2022

Moisture Watch

The moisture is largely unchanged throughout the medium term as we track the larger weather events over WA and this then filtering moisture throughout the country from northwest to southeast ahead of cold fronts. There will also be moisture spreading through the Coral Sea and into northern Australia via the easterly wind regime! That moisture over northern areas of the nation needs to be watched as we will see that turning back towards the country via being drawn south and southeast in upper northwest winds leading to rainfall chances coming up for QLD and the NT.

That moisture over northern Australia will spread south and southeast into the NT and QLD with the dry season weather starting to shift as we have moisture coming up. Further heavy moisture continuing over southern Australia, the weather here likely leading to higher rainfall than normal over eastern and southeast Australia. Another wave of frontal weather may drag in moisture from the Central Indian Ocean into the SWLD.

Temperature Anomalies

Temperatures are forecast to remain well above normal for many areas this weekend and into next week as a long fetch northwest to westerly flow distributes the warmth throughout much of inland Australia. Another wave of frontal weather moving into SWLD of WA leading to cooler than normal weather, actually quite cold over the coastal areas under persistent westerly winds. Seasonal weather over the east coastal areas of the nation. Humidity values may start to rise over northern Australia.

The heat values remain higher than normal over the north of the nation with elevated SSTs coming into play and with moisture spreading throughout the north of the nation, this could lead to a marked increase in humidity values ending the dry season for a period. That warmth may begin to clash with the colder and drier weather surging northwards over south of the country behind strong cold fronts and low pressure. So more dynamic weather is possible with severe weather chances also coming up as the red and blue shading begins to get closer!

Rainfall Anomalies

The moisture values remaining very high throughout the interior will eventually lead to cloud increasing initially, with rainfall likely to increase in coverage over the nation's central and eastern areas. The rainfall over the southeast areas on and west of the divide could be well above normal with low pressure stacking up in the westerly wind regime and topography enhancing rainfall. Further strong cold fronts and low pressure peaking over the SWLD leading to more widespread falls and with the SSTs continuing to run above normal offshore the west and southwest of the Ag Areas here, the rainfall could continue at above average values (as seen over the weekend 75mm observed in some areas).

Rainfall over the central and eastern inland of the nation is tending above average with a northern movement of the westerly wind belt flicking some low-pressure systems through southern parts of WA through SA and VIC and that may continue through this period, however given we are likely to have moisture running over the NT and into QLD, this could be lifted into widespread rainfall with low pressure forecast to be over QLD, NSW and VIC. Further moisture may activate into cloud bands offshore WA and this coming through with the next wave of rain and thunderstorms moving in towards mid month.

DATA - Refer to the video for further information.


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

A significant period of weather is developing through the short and medium term and careful analysis is required for each system and not getting too carried away with all the components in play. So, check out the video for the short and medium term.

00Z GFS - Precipitable Water Values - Next 2 Weeks

The moisture profile still remains excessive for this time of year and we have seen in previous months what that has resulted in nationally in terms of severe weather and flooding. That may be the case but in areas that are currently waiting for more general rainfall. Areas of concern for severe weather related to flooding and high levels of humidity is expected to be over the SWLD, through much of the southeast inland of VIC and NSW. SA may see the worst of the weather bypass the region but overall, the wettest period of the year may be on the cards for SA so certainly an interesting few days of weather modelling to come to see if this holds.

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 - very much a riverine flood look for parts of the southeast inland of the nation, especially northeast VIC and southeast NSW as most of what you see falling here will be rainfall on a snowpack so something to watch and if you are in areas close to river systems that record spring flooding be on alert and keep across forecasts. Widespread above average rainfall is expected through much of the southeast inland and finally more robust numbers for western VIC, NSW and back through SA too with some luck. But as always, the pattern will dictate where the moisture will be most productive!

More coming up from 8pm EST with a look at the models and rainfall.

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