We have been tracking this first rainfall event during a benign week of weather last week and now we are starting to see the ingredients unfold in real time. That is the form of the trough moving through SA and WA and another trough deepening through QLD into NSW over the coming 24 hours - moisture also being dragged in via easterly winds. The elements merging later tomorrow through mid week to kick off a hefty spring rainfall event.
But what about the follow up systems for SA and WA? Will that result in much this weekend?
The tropics are expected to wake up, will that shoot moisture south and east through QLD to bring more rainfall opportunities through the next week or so?
Lets take a look
Moisture Watch This Week - September 27th - October 4th 2021
Lots of moisture now surging through the nation and relatively good agreement for the unfolding influence this week. The moisture over the tropics is an area to watch, as that could increase rainfall chances in the second week of the outlook for QLD and NSW with another shot of moisture building from Indonesia.
Moisture Watch Next Week - October 5-11th 2021
Moisture running throughout the south of the nation combining with troughs with scattered showers and storms about. A moisture stream from the tropics through the Top End into the eastern inland could provide scattered showers and thunderstorms about. Moisture also dancing off the northwest of the nation at this stage staying offshore but could be absorbed into the upper level westerly winds and spread across the nation.
Rainfall This Week - September 27th - October 4th 2021
Very wet weather developing this week with some areas recording upwards of 100mm in NSW and VIC with a flood risk. Some of the better rainfall chances in months for QLD as well with a stormy outbreak later this week. The tropics turn active this weekend with an uptick in thundery weather. The west will see a follow up rainfall event with moderate rainfall later this week which will spread along the south coast of the nation.
Rainfall Next Week - October 5-11th 2021
Rainfall eases for parts of the eastern inland at this stage, however moisture plumes moving southeast from the tropics could be fed into eastward moving low pressure troughs from SA into the east, which may change the rainfall distribution and spread for NSW and QLD in particular. At this time the low pressure is forecast to sit further south bringing further rain to southern areas of the nation. Showers and storms increasing in a marginally more unstable airmass over the Top End.
Rainfall Anomalies Next 2 weeks - September 27-October 11th 2021
Very high chance of above average rainfall over the southeast which moderates along the south coast of Australia. Moderate risk of above average rainfall for the NT and interior parts as moisture shears southeast in the second week of the outlook. Near normal weather elsewhere.
Temperature Anomalies This Week
The weather cooler than normal, not by a huge amount over the south and southeast, with persistent cloud cover and rainfall, humid weather keeping the overnights likely above average, but day times below average with little movement in temperature. Up north the early build up is continuing to bring excessive heat levels to multiple districts.
Temperature Anomalies Next Week
The cooler bias continues for the south particularly the southeast inland with the weather dominated by low pressure and a southwest kick possibly bringing up colder air over the southeast states with persistent rainfall. Warmer weather with the early build up over northern areas.
DATA - REFER TO THE VIDEO FOR MORE ON THE DATA SETS.
GFS 18Z - Surface Pressure Pattern and Rainfall Distribution - Next 2 weeks - September 27-October 11th 2021
GFS 18Z - Precipitable Water Anomalies - Next 2 weeks - September 27-October 11th 2021
GFS 18Z Ensemble - Rainfall Accumulation - Next 2 weeks - September 27-October 11th 2021
You number will vary over the continent as we transition to thunderstorm activity - so please remember that all forecasts are flawed when it comes to summer rainfall, so use the rainfall as a guide away from organised rainfall events. Thunderstorms create havoc in preparing rainfall charts.
GFS 18Z - Temperature Anomalies - Next 2 weeks - September 27-October 11th 2021
And YES the rainfall chances do continue to build as we continue through October into November. Harvest could be tricky for many areas and the rainfall below could cause some issues around crop quality.
CFS - Rainfall Accumulation for the coming 6 weeks.
I will have a look at the severe weather risks for the nation as we track through the south and east over the coming week.