MEDIUM TERM FORECAST - THE SEASONAL SHIFT IS HAPPENING BEFORE OUR EYES.

Obviously there has been extensive coverage of the thunderstorm outbreak over much of QLD and NSW with damaging conditions. Thankfully you are here and if you are a farmer living in the region there is more detailed information about the risk moving forward and again next week.


For other areas, the same coverage will be applied for your region when weather parameters are off the charts, so don't think that there is a bias for the east with this service.


Now to the forecast - we know that the weather is shifting, we have more humidity building over the nation, easterly winds continue and the climate drivers are supportive of the wet weather redeveloping in the medium term for large parts of the nation, despite the lull for the very soggy southeast and southwest of the nation.


The east and north will be wet and stormy throughout this time, and that is thanks to the above average build up conditions which is in line with the Indian Ocean Dipole phase peaking in it's negative phase, the greatest impact of this climatic driver this time around has been on the build up over northern Australia so far.


That will play out for areas further south and east as the moisture is dislodged from the tropical north via upper level winds and bringing rainfall chances up for the end of the month for southern areas and into the eastern inland of the nation to kick off November.


Temperatures are expected to move well above the average during the coming week and the record heat over the NT and northern WA (some areas reaching 45C yesterday) will be moving south and east as well during this period.


The heat is the catalyst for bringing heavier rainfall potential through the nation in November.


Lets take a look

FORECAST CHARTS


Moisture Watch This Week - October 21-28 2021

No change from yesterday's guidance with moisture over the north and east on the periphery of the upper high and ridging through the central and eastern inland of the nation This will keep the area rain and mainly cloud free through to mid next week. Moisture over northern Australia expected to sweep through into WA before turning south and being absorbed into the upper westerly winds and begin it's journey south and east. A trough from WA will be the factor determining how far south this moisture comes and whether we see more widespread showers and thunderstorms for SA, VIC and NSW. A cold front keeping drier air back over WA.

Moisture Watch Next Week - October 29-November 5 2021

Still watching that large plume of moisture from the Indian Ocean which will add more moisture into the humid nation. The tropics becoming very soupy with above average humidity values, so this will just increase the risk of more cloud and rainfall chances as we move through the first week of November. This will end the drier and warmer spell over the eastern and southeast inland of the nation.

Rainfall This Week - October 21-28 2021

Ongoing showers and thunderstorms over northern and eastern Australia with the chance of heavy falls with severe weather. The storms and showers decrease a tad over the weekend but will be back next week with the new trough passing over southeast Australia. That will bring showers and areas of rainfall across southern of Victoria later tomorrow and into Saturday. Then dry weather resumes for VIC and will join SA and much of the interior back to WA with dry weather. The moisture over the northern parts of the nation will be shifting south taking the showers and thunderstorm risk with it. The SWLD looking relatively dry and settled for now.

Rainfall Next Week - October 29-November 5 2021

The moisture content in the atmosphere is very much above average nationwide, there will be pockets of drier air interspersed with this humidity but as we move into November, there will be more humidity than drier air and more widespread rainfall opportunities as we go. The fact the nation is warming up this week as we see more drier and stable air, is what we need to see for heavier spring and summer rainfall that we are accustomed too at regular intervals. So this chart will likely chop and change and become more colourful as we get closer to November.

Rainfall Anomalies - October 21-November 5 2021

Rainfall running well above average over northern parts of the nation and this risk is likely to shift south throughout the coming fortnight. With the high degree of uncertainty of trough development and evolution, placement and scale, the remainder of the nation is expecting seasonal rainfall at this time, HOWEVER, the green shading could easily move into the eastern inland in the coming week as we move closer to November. The drier bias is not quite there on the charts in the medium term.

Temperature Anomalies This Week - October 21-28 2021

No change from the guidance, warm over the southeast today and through Saturday before a cooler southwesterly moves in ahead of the next high. That cooler air remaining fairly coastal. Interior parts very hot as we spoke about. The record heat will calm down a bit over the next week. The southwest of the nation will remain cooler than average with another frontal burst next week with a nice pop of colder air once again after a warm weekend.

Temperature Anomalies Next Week - October 29-November 5 2021

The signal for that hot and humid air being dislodged from northern Australia through central and southeastern areas of the nation looks to continue so expect the humidity to increase, the thunderstorms risk to increase and day time temperatures to be the warmest we have seen so far this Spring. Cooler bias continues back through the southwest of the nation.

DATA - Refer to the video for more details


18Z GFS Surface Pressure Pattern and Rainfall Distribution - Next 16 Days

18z GFS Precipitable Water Anomalies - Next 16 Days

18z GFS Rainfall Accumulation - Next 16 days

12z CMC Rainfall Accumulation - Next 15 days

12z Euro Rainfall Accumulation - Next 15 days

18z CFS - Rainfall Accumulation Next 6 Weeks

More details coming up throughout the afternoon

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