MEDIUM TERM FORECAST - RAIN FOR QLD AND MAYBE OVER THE SOUTH NEXT WEEK.

Two systems on the board in the short and then in the medium term that need watching as they could both bring back some reasonable rainfall chances across the nation, particularly the east and then across the south as we head into September.


Expected rainfall across all data sets for the coming 2 weeks.

Expected temperature anomalies for the coming 2 weeks.

Lets take a look at the data sets.


GFS 18Z - Surface Pressure Pattern for the coming 2 weeks

The main rainfall event this week is ongoing Tuesday and into Wednesday with a low expected to move eastwards by Thursday. A weak trough will follow this system through the southeast during Friday with a few showers. The front comes in from WA and wraps into a low pressure system over the Bight with showers returning to coastal areas of SA, the low and trough then meeting some moisture over the east which will kick off showers and storms through NSW and QLD, falls could be quite heavy in some locations, we have seen different looks with showers heavy along the coastal areas with the onshore winds combining with the upper trough. Then a larger scale system is forecast to move over the southwest of WA and extend towards SA mid to late next week, that system may bring some moderate to heavy falls through SA into VIC and NSW. It has been persistent on the charts during the past four days. Noting too the moisture over the north des return with humid build up weather redeveloping.

GFS 18Z - Precipitable Water Anomalies for the coming 2 weeks

The PW anomalies tell the story with the drier surge following todays system in the east being driven through the entire nation. The moisture over the north will be flushed out with a cooler airmass. Then we see moisture values increase over WA and for QLD later this week into the weekend with onshore winds developing, this overrunning the drier air. A large moisture plume over the eastern inland will spread south and southwest through the eastern parts of the nation and also return over the north of the nation as well. At the same time we have moisture building over the western parts of the nation with another rain band likely to form at some stage next week, on and east of a front and trough passing through the nation.

GFS 18Z - Precipitation for the coming 2 weeks

Rainfall heavy today over the east coast, the rainfall is in the process of easing for the inland areas, with a cold dry southerly clearing conditions further west through inland NSW and northern VIC. The nation will be settled over the rest of the week away from SWLD of WA an showers with moderate falls over the southeast of VIC. A weak trough may kick off those showers on Friday through the southeast with light falls. Then a low pressure system over the Bight during the weekend may trigger showers for the south coast of SA, the trough ahead of the low may bring spark showers and storms over the inland of NSW and QLD during Sunday if not early next week. An upper trough keeps the showers and storms persisting over the inland areas before a stronger front arrives from WA through SA, that has the potential to deliver widespread rainfall over SA, VIC and NSW mid to late next week.

Euro 12Z - Simulated Satellite for the coming 10 days

And it is not only the GFS that sees that system for the south of the nation next week, the Euro also supporting the development of a large cloud band from the northwest to southeast with widespread rainfall possible.

CMC M 12Z - Rainfall for the coming 15 days

Looking at the rainfall data sets for the coming 2 weeks, and many want rainfall and there is reasonable opportunity. The CMC does not see the widespread heavy falls for inland QLD as some other models but curiously has widespread inland rainfall for much of the nation. The rainfall for the southeast is currently falling and there will be follow up however CMC says not as heavy as this event. The model does bring in frontal weather, but the y are less frequent. The north sees an increase in humidity as we roll into September, this leading to showers developing for the NT, WA and QLD. If this weather develops, then rainfall chances for inland QLD will come up.

GFS 18Z - Rainfall for the coming 15 days

GFS is identifying the inland rainfall event for QLD, with all models indicating that it will fire off along an upper trough over the eastern inland. The weather over the southeast and southwest will be changeable, and rainfall will likely be regular, but not as heavy as the winter rainfall of July. Inland rainfall is becoming more widespread but not as heavy as the CMC but the idea is the same of moisture increasing over the nation and rainfall chances therefore increasing.

Euro M 12Z - Rainfall for the coming 15 days

The Euro sees the inland rainfall event for eastern QLD but not as heavy as the GFS. The rainfall event underway over the southeast of the nation sticks out like a sore thumb over the southeast. The coastal areas of southern Australia wouldn't see as much rainfall, but this may change with the approach of a stronger front mid next week which the deterministic data does suggest is on the cards. Moisture is increasing over the north of the nation which increases the risk of rainfall over the north and eastern inland which may see rainfall chances creep up as well.

Temperatures are largely unchanged from yesterday. There will be some warming up of the nation next week, after a run of below average rainfall days coming up this week. The temperatures will be well above average for most of southern and eastern Australia if we see the front stand up over the Bight and drag in the warmer air from northwest Australia.


Until then we have got to deal with a number of frosty starts this week once the low moves further away and skies clear.

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