MEDIUM TERM FORECASTING - THE WEATHER TURNING HUMID AND UNSETTLED FOR MANY.

No change to the overall guidance as we wrap October and kick off November, the humidity values are set to increase, and combine with the unstable airmass building over the northern and eastern areas, to see showers and storms become more widespread. Upper level winds and the synoptic pattern allowing this moisture to be pulled south and east.


The west has seen record rainfall for October for a few locations showing that areas are continuing to be impacted by the IOD and this driver's influence will begin to impact areas further east and southeast in the coming weeks. We can already see it on the charts.


Lets take a look

FORECAST


Moisture Watch This Week - October 27 - November 3 2021

The forecast scenario has not changed in terms of the mechanics of moving the moisture around the country. So the impact zone is unchanged. What is changing is the placement of the low pressure in combination with this moisture and this is where your rainfall forecasts keep changing on your apps and other websites that you can obtain the data. It is futile playing that game of guessing how much rainfall you will get, the impact from the moisture will be felt far and wide this week and we are starting to see that through NT to SA today and the east from tomorrow. It repeats itself again this time next week.

Moisture Watch Next Week - November 4 - 11 2021

Multiple plumes of moisture over the nation will continue to bring elevated rainfall chances for the first half of this period, some modelling suggests drier air may surge through southern states with the moisture pushing north for a period towards the 8-11th of November but again the further you go out, the less specific you can be, but a prolonged period of humidity for much of the north and east is expected.

Rainfall This Week - October 27 - November 3 2021

Rainfall largely unchanged from yesterday for the coming week, with the main rainfall expected over the NT with the tropical weather increasing, showers and thunderstorms pooling through the central interior and that moisture being drawn southeast ahead of a trough tomorrow and then another trough this time next week. That lead trough coming through the southeast tomorrow will spark severe storms over northern NSW and southern and eastern QLD during Friday into Saturday. Rain easing for southwest WA.

Rainfall Next Week - November 4 - 11 2021

Rainfall continues over northern Australia, extending southwards through the nation and then southeast with troughs and low pressure with widespread falls. Uneven distribution of rainfall likely with thunderstorms involved. There is evidence in some medium term modelling of a larger scale widespread rainfall event for parts of SA but more likely over QLD, NSW and VIC through the first week of November.

Rainfall Anomalies - October 27 - November 11 2021

Rainfall anomalies are still generally increasing across the central and northern parts of the nation in relation to the up coming 7-10 days, but it is what happens beyond the 10 day mark that is very tricky to pin down, but all modelling as discussed has widespread rainfall, but who gets what is still too hard to call. Seasonal values in the west after a very wet October.

Temperature Anomalies This Week - October 27 - November 3 2021

Temperatures moderating over the SWLD from the colder conditions of recent days, the temperatures over the east by contrast quite warm with a nice pulse of warmer weather coming in from the northwest. The northern tropics still very hot but conditions will begin to moderate as rainfall coverage increases.

Temperature Anomalies Next Week - November 4 -11 2021

The upper high over the northeast of QLD will keep the temperatures up. increasing rainfall over the NT will see temperature values come down and those moderating temperatures over inland areas will extend further southeast across the nation with thick cloud cover, scattered rain areas and thunderstorms. Now while it may not be cold, the trend is for below average temperatures over large parts of the nation. Where it will feel cooler is over the SWLD of WA.

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 Precipitable Water Values - Next 16 Days

The yellow is very high PW values, the red shading extremely high values. Flash flooding is a significant risk under these values throughout the southern and central then eastern areas of the nation with the troughs passing through that moisture profile.

18z GFS Rainfall Accumulation - Next 16 days

12z CMC Rainfall Accumulation - Next 15 days

I am leaning more towards this solution.

12z Euro Rainfall Accumulation - Next 15 days

12z CFS Rainfall Accumulation - Next 6 Weeks

More details coming up throughout the afternoon and tonight - stay tuned, the weather is about to get very active yet again!