As expected we are moving into the dry spell with the high pressure belt in full control over NSW, the weather unchanged for most of this week. The onshore winds are expected to develop over QLD where the showers will be but for NSW, most of the coast should be dry with a mixture of clouds and sunshine, perhaps a shower possible over the north coast but for the most part, a fairly benign week is likely.
There is a weak system passing through VIC tonight, that system has created a little bit of forcing through the atmosphere hence the cloud cover, but there is no trigger so just cloudy periods about this afternoon and this evening, that might just take the edge off the frost risk a bit overnight. There has been some light rain areas over the northwest of NSW today but nothing in the gauges yet.
Frost Risk Forecast Monday.
The frost risk could be mitigated by the cloud cover that has developed in the middle layers this afternoon through inland areas but again it could surprise so a heads up once again for frost over the slopes and GDR.
The medium term, from next weekend into the following week, we are seeing trends in the models to indicate a larger scale system develop over the central and eastern parts of the nation which looks to tap into the deeper moisture supply which is of interest for those who want some follow up rainfall.
The weather is expected to turn interesting in about 1 week, this will be the focus of the medium term forecasting, many looking at wanting more rainfall over the south of the nation, some are not! So lots riding on the forecasts this week.
This will be the period to watch for eastern areas of the nation, the weather is anticipated to turn dynamic with the potential for thunderstorms moving throughout the east. This is over a week out still.
Lets have a look.
00Z GFS Surface Pressure Pattern for the coming 16 days
The pressure pattern is quiet this week, that is well documented. The first change coming through the southern parts of the nation hits WA during Wednesday and slides, weakens on approach to the southeast states. That will introduce warmer weather for southern areas and then showers developing for SA, VIC and TAS, perhaps southern NSW but otherwise the inland areas remain dry. Next week the stronger system that comes through southern WA moves over SA and clashes with the hot airmass driven south through the northwest flow, interacting with moisture over the eastern inland with a larger area of rainfall and thunderstorms developing. That could bring the heaviest rainfall of the month for SA, VIC, NSW, QLD and TAS. This system may take a while to move through. Fine weather over northwest and western parts of the nation while the east is drenched under this guidance. The tropics turning humid and unsettled during the next week.
00z GFS Rainfall for the coming 16 days
Rainfall fairly light on for the week across the nation, with only coastal areas of the southeast and the eastern parts of QLD expected to see any rainfall this week. Then a change rolling through WA, will introduce showers and perhaps some moderate falls for the southwest of WA. The first front will weaken as it passes through to the southeast states bringing showers to southern SA and into VIC and TAS. A few light showers are possible for southern NSW later this week. A stronger system coming through WA Thursday will kick along the showery weather for the weekend over the southeast states with some moderate falls for TAS and southwest VIC. Showers may creep into southern NSW Saturday into Sunday. Then the stronger feature will pass through the southern and eastern states from early the following week with moderate to heavy falls possible in that configuration for pockets of southern and eastern Australia. We will see it chop and change so this will be the area to watch. When the east turns wet, the east will likely be drier. The north of the nation will see an increase in humidity
00z GFS Precipitable Water Anomalies next 16 days
The PW anomalies again painting the picture of the drier air under high pressure being overrun by the moisture that builds over northern and eastern Australia in the persistence of easterly winds. Those easterly winds will become more frequent as we track through spring and into the summer, so the importance of them for areas of the east are a given, but for central areas of the nation too, very important. The system from the west runs into the moisture drawn through eastern Australia seeing larger scale rainfall break out. The anomalies suggest that even though modelling is showing moderate rainfall, there could be some heavier falls than what is being indicated.
00z Euro Surface Pressure Pattern for the coming 10 days
The weather is expected as you know quiet for much of the nation. Lets take a look at the middle of the week and the first front is passing through WA bringing a burst of moderate showers, high pressure over the central and eastern parts leading to clearing skies over the southeast and a persistence of clearer weather for the east. Warmer temperatures are expected to build through the outlook period as a northwest flow gets going for the southeast states ahead of that front. The first front may bring more rainfall if Euro is right to the southeast and southern states. A follow up system, similar in scale to GFS, looks set to pounce on the southeast early the following week, but is drier than GFS. So there are some divergence on where the moisture is getting involved with the frontal weather moving from west to east.
00z Euro Rainfall for the coming 10 days
Rainfall largely unchanged from this morning, but there has been an uptick in numbers for the southeast states Friday through Saturday. But the model is different to GFS for the medium term bringing less rainfall in that system the following week, so again there is divergence, but we are now as expected seeing more consistency for the medium term. Now we wait and see how the data holds in coming days.
00z Euro Precipitable Water Values next 10 days
You can see the moisture building in the easterly winds for the eastern parts of Australia with the onshore winds. Another shot of moisture coming in from the northwest via the jet stream may sneak in ahead of the front coming through WA mid to late week, that could provide more rainfall than what was forecast in this evening's forecast packages from the BoM. I will have another look at that tomorrow morning and introduce higher rainfall into rainfall forecasts into the latter part of the week. The moisture looks to be shoved out by the strong and gusty westerly change with a larger system the following week where you can see with the GFS, that model holds more moisture in place bringing up rainfall chances.
Rainfall for the next 10 days
Rainfall for the coming 5 days, very lean and the majority of it will be linked to easterly winds along the north coast and a little rain about the northern inland this evening. Perhaps a light shower or two over the southern inland west of the divide on Monday with more cloudy skies. Then we have to wait until about Friday for southern inland areas and then the remainder of the state for the following week in the day 8-10 window which most of this will fall. The numbers therefore WILL change and move around in accordance with the guidance.
Plenty of weather to talk about this week - I will update the two week outlook tomorrow with a detailed look at conditions surrounding that first system coming out of the Indian Ocean.