The same pattern continues this weekend with a series of troughs and two fronts in a moist northwest flow, bringing showers/rain to on and west of the divide, with light to moderate rainfall expected. The wettest period for NSW this weekend will be Sunday.
Today we have seen a warm front pass through the south of the state with a band of cloud, some patchy light showers and warmer temperatures as it passes through the region.
Satellite Imagery of that front bringing in the moist warmer airflow and the gusty northwest winds.
Here is that process on the PW charts - note that dry air from this morning being kicked out from the west with a moist airmass being denoted by the cloud and light rainfall. Science before your eyes!
Temperatures are warming behind the front, and tonight will be much warmer than last night through much of NSW.
Temperatures mid afternoon on Friday
The first front and trough with the moisture will lift northeast through the state Sunday before slowing down over the northern inland of NSW.
A secondary frontal boundary will then move in under the lead system and propel it north, this invigorates the feature and tapping into a moisture stream from the northwest, leading to another burst of rainfall for northern NSW.
The second front will bring another burst of showers to the southern inland parts of the state, with those showers turning to rain over the southeast. There is the chance of a thunderstorm and hail with the feature as it rolls through the southern inland.
The weather starts to ease through Tuesday as the airstream begins to dry out and then by mid to late week, the whole state turns dry and settled with high pressure.
Systems to watch in the medium term are covered off this afternoon in the medium term forecast pinned to the top of the page.
This is the weather to watch in the medium term, the PW values are increasing by mid month with the pattern flip in place.
This is GFS in the middle of August showing significant increase in moisture values.
This is the Euro showing moisture beginning to stack up with the high finally moving into the Tasman directing southeast to easterly winds over the eastern seaboard. The northwest flow through WA helping to pull moisture south from Indonesia ahead of the next cold front in a week's time. So there is interesting weather building from the second week of August.
Lets head into short term modelling.
00Z GFS Surface Pressure Pattern for the coming 16 days
The pressure pattern is becoming unstable with a warm to hot moist northwest flow beginning to be lifted by the cold fronts and troughs moving out of the west. We will see rainfall breaking out over SA, VIC and NSW during Saturday and then into most of NSW and southern QLD during Sunday as the trough lifts northwards. The second front will lift the remaining moisture over the inland of NSW and drawn in deeper moisture through southern QLD and northeast NSW with the rainfall tending heavy at times about the GDR. The southern areas will see widespread showers developing during Monday and Tuesday with the passage of the front with hail and thunder over VIC and southeast SA. The weather then returns to dry through most of inland areas of NSW and SA from Tuesday though showers may continue in shallow moisture in onshore winds with light showers for coastal SA and VIC. The weather will take to this time next week to settle back to fine and clear weather for all parts of the southeast
00z GFS Rainfall for the coming 16 days
Rainfall is largely unchanged from overnight with the rainfall connected to the westerly wind regime, two frontal passages and the deepening moisture supply streaming in from the northwest ahead of the fronts as they rush through. The weather is expected to ease from mid to late next week as high pressure comes in so you can see no more additional rainfall under stable air from next weekend, that carries through to mid month over the southeast states, while rainfall returns to northern Australia and back over WA.
00z GFS Precipitable Water Anomalies next 16 days
This product again shows the shift in the conditions after we get through the last of the frontal weather. The nation begins to be dominated by high pressure as it digs into the southern states. The more settled weather expected from Thursday for several days next week. As that happens, the whole pattern resets and we see easterly winds strengthen over the north and east and finally gives the eastern inland a chance to see moisture return, coastal showers return to the east coast, giving the south a chance to dry out. It is looking more likely that a rainfall event may get going over QLD next weekend if an upper trough can make the journey from Central Australia into the north or central parts of QLD. No doubt at where the high is being forecast to be that there will be onshore winds over northern and central QLD bringing in moisture. Then out west we watch the moisture surging southeast into frontal weather approaching next weekend which may bring a separate rainfall event to the west later next weekend Another rainfall event may develop over the northeast with a deeper moisture plume over much of QLD. That is the second time this model has shown this today for mid month, that event would be more widespread if it verifies.
00z Euro Surface Pressure Pattern for the coming 10 days
The pattern largely unchanged from this morning with two frontal waves tapping into large amounts of moisture streaming out of the northwest and extending over VIC and NSW, then into QLD this weekend into early next week. We have already seen that take place this afternoon with the moisture returning through the southeast inland with a weakening trough and moisture surging southeast. We see a front come through Saturday with the last of the fronts move through Monday through Tuesday with a colder southwest flow redeveloping. The weather will clear under that high pressure system moving in as the westerly winds retreat south but it may take up to a week from today for coastal areas of VIC, SA and TAS to clear totally. Inland areas should dry out quicker over the southeast. Note the upper trough over QLD later in the outlook and another long wave building off WA next weekend, these two areas will be the focus of medium term forecasting over the weekend and may provide the next batch of rainfall into the second week of August, that remains unchanged this evening.
00z Euro Rainfall for the coming 10 days
Rainfall again largely confined to the next 2 systems rolling through the southeast, one on Saturday and Sunday and another burst of rainfall coming through on Monday through Tuesday before we see clearance. Some lingering showers possible during Wednesday over the southern inland however the weather should clear out during this time next week with more sunshine and milder weather developing as a northwest flow develops around the high moving to the east. So drier weather expected from Wednesday onwards through next weekend for most locations. If the winds turn more easterly, then I may reintroduce showers to the east coast.
00z Euro Precipitable Water Values next 10 days
The Euro is similar to the GFS with moisture likely to reset under the new high pressure system next week. We can see a good supply of moisture coming in ahead of frontal weather over the southern and eastern states over the coming few days, leading to once again light to moderate follow up rainfall. The northern inland of NSW and southern QLD could surprise during Sunday and Monday as an upper trough deepens with the second system surging northeast bringing a colder southwest shift to the southeast state. In the later part of the next week into the weekend, we can see moisture developing over QLD and WA, where this will be the focus of the medium-term forecasting as two large cloud bands could develop in response to the moisture and troughs combining. Rainfall coverage next weekend is hard to pin down and better clarity will come Sunday night with the forecast packages and during early next week once the long wave over the southeast moves east.
Rainfall for the next 10 days
Rainfall totals have largely remain unchanged from this morning given that the next wave is set to pass over the region. The falls somewhat heavier over the northeast of NSW along the GDR where the moisture deepens and stalls out Sunday into Monday with some reasonable rainfall over 30mm possible for a small area between Tenterfield and Walcha. Otherwise the showery weather will be most widespread Saturday and Sunday then Monday afternoon through Tuesday afternoon before it begins to ease from north to south to become clear by this time next week.
More weather details to come with another national wrap on Saturday and a look at the system crossing through southern Australia. Have a great Friday night.