The weather is expected to deviate from the dry season goodness of recent days over the north and adopt a more traditional build up feel with humidity set to rise incrementally as we go through this week. A return to showers and thunderstorms are likely but the upper high is keeping a lid on things for much of the outlook.
Over the south the drier air is anticipated to hang on for a while longer but we will see moisture sweep in later in the period and this could result in an uptick in the chance of elevated showers and storms for communities down the Stuart Highway towards SA.
Lets take a look
Rainfall for the next 10 days
Limited rainfall for the outlook period, but this forecast may be revised in coming days if the upper high weakens allowing for support of showers and thunderstorms to return. Some modelling supports slightly colder upper levels bringing back the chance of thunderstorms and showers across the NT by end of this period. We will see, for now the showers few and far between over the Top End with most days areas having a 10-30% chance of rainfall for now.
Euro 00z - Surface Pressure Pattern and Rainfall Distribution - Next 10 days
Modelling is largely unchanged from this morning which in a sense is good news for forecasting, not great for those who don't want the rain, who do want the rainfall. A trough over in WA is expected to deepen with a decent slab of moisture being drawn into this feature triggering widespread showers and a few thunderstorms Sunday. In the east onshore winds are still expected to push on the NSW coast with a slow moving boundary that will stall out over SEQ during Monday. Light falls with that and a noticeable uptick in humidity. A surface trough over the inland portions of QLD will kick off a few showers and thunderstorms along it's axis during Monday and Tuesday before that moisture is drawn south and lifted by a stronger trough passing out of SA later Tuesday. That will fuel more robust showers and thunderstorms for NSW and VIC with moderate to heavy falls, there is a risk some storms could be severe Tuesday with heavy rainfall and damaging winds a threat. Then wet through the southeast and eastern inland for most of next week, another change to roll through WA holds better rainfall potential for SA for the poor old crops hanging on for dear life and the tropics, suppressed but will turn more stormy once we get the upper high out the way later next week.
Euro 00z - Precipitable Water Anomalies - Next 10 days
The process to override the drier air takes place this weekend with a good shot of moisture coming in from the Indian Ocean, which you can see on the satellite imagery, denoted by the high and middle level cloud, that will be drawn into a trough over the SWLD producing showers and storms from Sunday. Another shot of moisture will be developing via easterly winds in QLD and NSW with that moisture expected to travel west through the eastern interior, then being drawn south into NSW and VIC. This moisture will then be merging with the remnants of what comes out of WA to produce a large area of above average moisture content in the atmosphere, leading to widespread rainfall. Then for the remainder of the period, keeping watch of moisture being drawn in via the mid latitude westerly winds over the Indian Ocean into a follow up feature over WA, that holds better potential for SA in the end of this period.
Euro 00z - Rainfall Accumulation - Next 10 days
Rainfall distribution as mentioned, uneven through the eastern states, that is in terms of totals you will see. It will come down to thunderstorms and this is why I refer to convective setups lead to uneven distribution of rainfall. So keep that in mind looking at ALL rainfall products out there. The wettest weather clearly the southeast and eastern inland of NSW and VIC where flooding is a risk. The east coast should see an increase in shower coverage leading to welcome falls. Light falls for now over SA, but numbers will likely tick up IF the weather out west can be in phase over the region, the second feature offering the most hope. The west of the nation, looking damp over the SWLD with periods of rain and thunderstorms from time to time in the early part of the period but the follow up system could drop a lot of rainfall if the moisture can get in front of the low and front slowly moving in offshore. The tropical north, isolated showers and thunderstorms about, you know the drill, down the road could get 1 inch of rain in 20 minutes and 2km away get a nice outflow breeze from it with not a drop.
A closer look - showers and thunderstorm coverage is determined by the presence of the upper high and if that system remains in place it will suppress activity for longer, if it erodes then the coverage of rainfall will return earlier.
GFS for comparison for the coming 2 weeks.
The coverage of rainfall will increase after the 10 day window.
More details coming up on Saturday morning.