The model madness begins again. We know this week away from the storms over the eastern seaboard and across the tropics, things are fairly quiet nationwide. We are likely to lose the rain band in 12hrs over WA with not much left by morning as that crosses into a high pressure ridge which will erode the system.
Those wanting more rainfall through SA, VIC, NSW and QLD, it is time to pay more attention to the tropics and the moisture being dislodged from that region and fed into the southern and eastern parts of the nation via the upper level winds. For WA, we need to see these heat troughs form and lose the westerly wind regime. For the tropics, we need to lose the upper level high and have colder more unstable air form.
All of this likely to start unfolding in the medium term.
The pressure pattern is supporting the rainfall to be coastal with a ridge, upper high moving over large parts of the nation. On some of those charts, you can see that the rainfall is on the edge of this area of sinking air, clearly placing a dry spell over most of SA, western and northern VIC, western NSW and western and southwest QLD. This feature will be with us for the best part of this week. The remainder of the nation will see uneven rainfall distribution with showers and thunderstorms, mostly in the east and north. The west likely to see rainfall reduce for a period before storms spread south from the tropics.
UKMET - Rainfall Next 7 Days - LOW CHANCE
This is where will see the upper high begin to be overridden by the moisture aloft and more low pressure building over the nation thanks to high heat over interior parts, destablising the air and seeing low pressure form. A trough from WA will roll through SA in the middle of next week and that will link up with moisture to bring the next batch of showers and thunderstorms, initially from WA then into northern and western SA and into the southeast and eastern inland towards month's end if not early November. Timing of that passage is atrocious and will be refined during this weekend so just know that is the window of opportunity and you will see numbers bouncing around. The tropics turning more active through this period and storms may turn severe and become heavy at times. And more storms likely for inland parts of QLD and along the coastal fringe. Will be watching the SAM to see if that turns sharply positive in this period.
ICON - Rainfall Next 8 Days - LOW CHANCE
CMC - Rainfall Next 10 Days - LOW CHANCE
EURO - Rainfall Next 10 Days - LOW CHANCE
ACCESS - Rainfall Next 10 Days - MODERATE CHANCE
KMA - Rainfall Next 10 Days - MODERATE CHANCE
GFS - Rainfall Next 16 Days - LOW CHANCE
This is still the most useful set of data right now, it is overlooked as the resolution is not as high as the other deterministic data but it is MORE reliable than the above!
GFS - Rainfall Next 16 Days (median of 35 members) - LOW CHANCE
CMC - Rainfall Next 15 Days (median of 30 members) - MODERATE CHANCE
EURO - Rainfall Next 15 Days (median of 51 members) - LOW CHANCE
The wet run through harvest and into December continues on modelling so make preparations for this to be the case over northern and eastern Australia. Even portions of VIC and SA as well as southern WA also wet for this time of year IF this is right!
CFS - Rainfall Next 6 Weeks - MODERATE CHANCE
More details from 7am EDT. Have a great evening.