NATIONAL WEATHER WRAP - SATURDAY EVENING

Headlines


  • A warm spell to continue into Sunday with well above average temperatures for the northern states with increasing humidity values.

  • A cold front surging northeast from the south is expected to drive widespread showers into SA and western VIC later Sunday.

  • Widespread rain breaking out through NSW on Monday with temperatures turning sharply colder.

  • A surge of well below average temperatures are expected from Tuesday right through the nation.

The weather is expected to turn quite dynamic throughout the coming 36hrs as we see a clash of the warmer air throughout the central and eastern inland clashing with the colder drier surge of air coming into the southeast states from tomorrow. This clearly will be the area of significance in the coming days.


Satellite shows all the elements are there ready to be utilised for the rainfall event on Monday. The sliver of moisture is still holding firm over parts of the inland of SA through NSW today with areas of high cloud moving through. You can see the cold front on the approach from the southwest with a parcel of cold air expected to be driven north over the nation, combining with the warmer air and the humidity to see rainfall chances increase over the east. Low cloud over in WA producing one or two showers but for the most part it is cool and fine. Hot to very hot over the north with sunny skies.

The elements are there and will all start to clash and interact during Sunday into Monday over VIC and NSW. This is a very spring like system.

Temperatures this afternoon are well above normal for most locations over the north and east with a west or northwest wind regime. This is all ahead of the long wave expected to approach the eastern inland on Monday. The run of above average temperatures are expected to peak during Sunday.

The cooler air is still trapped back over WA where the run of seasonal to below seasonal values will continue but the north is still hot til Tuesday.

Radar is very quiet nationally with the wettest weather over western TAS with a weak cold front passing through in the westerly airstream. Light showers of WA and a patch or two of light spits over NSW.

Rainfall for the next 10 days

The major rainfall event is still anticipated for the southeast of the nation where the bulk of the rain will fall during Monday through Wednesday. Scattered showers with a few storms are likely for SA and western VIC with the front later tomorrow into Monday. The rain band may even creep into southern parts of QLD with lighter falls. Then a low pressure system is expected to form along the coast with moderate to heavy falls possible, but dependent on the position of the low in relation to the coast. Then conditions ease mid week for the east, with showers returning to the west with the next set of cold fronts. There may be showers off and on over the northern NT and Cape York.


THE MODEL DATA


00Z GFS Surface Pressure Pattern for the coming 16 days

GFS continues to strengthen the rainfall signal for the southeast of the nation with a strong cold front expected to bring a burst of widespread showers with thunderstorms possible. The airmass quite dynamic with the cold air and warm to hot air with the introduction of moisture combining to bringing the chance of active weather. The weather turns colder from the south and west throughout the nation from Monday into Tuesday and then extending north with the boundary flushing out the moisture from the tropics. A low forming on the front will bring the chance of severe weather over the east coast of NSW and maybe Gippsland. Will keep watch on that. Another round of fronts start to move closer to WA from mid next week with that being the next belt of showers throughout the the SWLD. No rainfall is expected for inland areas at this time. Need to see that Indian Ocean wake up a bit more! The low pressure system on the east coast will begin to move off mid week.

00z GFS Rainfall for the coming 16 days

Rainfall is expected to be widespread throughout the southeast of the nation, with moderate to heavy falls over VIC and NSW with the low and front passing through. The weather is expected to turn drier over inland areas of the east from Tuesday, though colder air aloft may bring a few showers about the ranges before everything clears out mid week. The rainfall over the west will return with the frontal weather expected to increase. Then that frontal weather may return to the south and east to finish the month. In the medium term, the weather continues to show some rainfall opportunities for larger parts of the nation as we enter September but as with this time of year we are looking at trends. We have seen through this week how the impending rain event evolved on the charts rapidly.

00z GFS Precipitable Water Anomalies next 16 days

The moisture surges out of the northwest and north, absorbed into the frontal passage as it comes through the southeastern parts of the state. That could see moderate to heavy rainfall evolve, the deeper the moisture, the more productive the rain band. That moisture then is blasted out by the dry surge moving north and northwest throughout the nation in a colder southerly flow. The weather is expected to turn dry over the northern tropics with the cooler air reaching the north by Wednesday, though humidity may remain high over Cape York. Then we watch the moisture return over WA mid to late week and see how that comes across the nation with the next fronts as they work their way eastwards. Need to see that Indian Ocean wake up a bit more to verify the trends we have been seeing in the global climate forecasting.

00z Euro Surface Pressure Pattern for the coming 10 days

Solid system rolling through the southeast in the coming 3 days introducing a very cold and dry airmass throughout the southern and eastern inland of the nation. A band of rain is expected to form along the boundary where the moisture in the warmer air clashes with the colder dry air. This will be the major system of the outlook period. A low will likely form along the front Tuesday which will deepen offshore NSW before clearing east. A new high will clear the weather over southern inland parts of the nation. Then the next set of cold fronts will pas out of the west of the nation into the southern inland bringing the next chance of rainfall to the east at the end of the month or into September. The north still expected to see the showers with the easterly pulse of moisture then a dry surge mid week. The heat values over much of the nation will reduce over the course of this week.

00z Euro Rainfall for the coming 10 days

Rainfall is likely to be most widespread and heavy over the course of the next 3 days with the best of it over NSW and eastern VIC. A low pressure system forming will dictate where the heavy falls will develop. The rainfall lighter and patchier further west through NSW into SA and western VIC with some light to moderate rainfall coming into southern QLD. The east dries out at this stage from Wednesday night into Thursday. Then we have another set of fronts out west with rain returning to the west from the middle of next week. The weather over the north will give rise to a few showers before the dry surge arrives.

00z Euro Precipitable Water Values next 10 days

The deepening moisture levels that were indicated a week ago for this period that vanished from modelling is now back for the next couple of days. This will happen over and over again I think this spring time with the weather pinging trends and then dropping it before it returns a few days out from unfolding. The moisture will be flushed out mid week before it returns from the west mid to late week and then over the north again this time next week. Some of this moisture will drift eastwards in about a week.

I will have another 2 week forecast coming up tomorrow and we will have better clarity for those eastern states on how much rainfall we can expect in the coming 2-3 days and the severe weather threat.


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