HARVEST WEATHER OUTLOOK - NOVEMBER INTO EARLY DECEMBER.

Let's take a look at the latest data coming in from the climate and global models this morning - will the wet and humid signal continue for the nation??


FORECAST


% chance of exceeding the median rainfall next 6 weeks - October 22nd-December 6th 2021

Not much change from the previous update however the rainfall signals are strengthening as we move into early December for northern and eastern Australia so much of the NT, QLD and NSW will see above average rainfall, NOT ALL, but your chances are running high. Rainfall as we have seen is more uneven in distribution between major rainfall events via showers and thunderstorms. The rainfall bias continues to trend lighter the further west you go through the nation but at this time, most of Australia should see seasonal to above seasonal rainfall values for the coming 6 weeks. The tropics are very active and we will see this play out from this week and throughout the coming period, spreading through WA and down into interior portions of northern Australia into central areas and then onwards into the eastern and southeast inland. Severe thunderstorm outbreaks will be running high.

% chance of exceeding the median temperatures next 6 weeks - October 22nd-December 6th 2021

No change from the previous update. The higher than average rainfall for the north and east will see temperatures begin to moderate after a hot and humid few months. Below average temperatures are likely for the period over eastern NSW west of the divide and through southern inland QLD with the frequent rainfall and thunderstorm events. The SWLD remaining cooler than normal with ridging persisting and the potential for the positive SAM. Seasonal values most elsewhere with that conditional upon rainfall and humidity values, but searing dry heat nationwide like a few years ago, HIGHLY UNLIKELY.

CLIMATE DASHBOARD

No change to the guidance in the climate models this week which is nice, we know the Indian Ocean is negative phase and we are seeing that impact on the overall medium term forecasts with moisture streaming in from the northwest. This influence will continue for the coming 6 weeks across the nation. The SAM is currently trending more positive as we end October and I am of the belief as we go through November, the SAM is likely to be positive, thus increasing rainfall chances along the east coast as you can see in most data sets below. Finally the ENSO which I will speak more about in another post is likely to shift into La Nina during the latter part of November into December, HOWEVER, the shift into the La Nina and the impacts felt in Australia, usually has a lag of about 4-6 weeks and so this is likely to be experienced after Christmas at this stage over the continent. The bigger impacts on that over the north and east.


DATA - Refer to video for more on these sets of data


RAINFALL

Euro Rainfall Accumulation Ensemble Data - Next 6 Weeks - October 22nd -December 6th 2021

A very wet signal for much of the nation with potential flood risks for the southeast and east with these rainfall values. Higher humidity values and warmer temperatures will increase your risk of mildew, rot and other fungal issues for your crops, particularly those summer crops that are in flower, fruit and at risk of impact from these conditions in the east and south. The severe weather risk from thunderstorms is running high to very high through this period with rainfall likely to be derived from storm outbreaks through the east and periodically, large scale rainfall events sweeping west to east.

Euro Rainfall Accumulation Control Data - Next 6 Weeks - October 22nd -December 6th 2021

This highlights the convective nature of rainfall - it will not end up like this but that is a wet look for the nation running into December.

Euro Rainfall Anomalies - Next 6 Weeks - October 22nd -December 6th2021

That is a VERY WET look or northern Australia with rainfall anomalies 100-200mm above normal for the 6 week period. The rainfall anomalies along the east coast 50-100mm above normal. At this stage most of the nation seeing a 25-50mm increase on normal for this period. That is a wet signal.

CFS Rainfall Accumulation Ensemble Data- Next 6 Weeks - October 22nd -December 6th 2021

We track this daily here, and no change to the signal of wetter bias the further east you go and seasonally it is what you expect as you travel north with the tropics waking up. The tropics are wide awake earlier than normal and this will impact late Spring and Summer rainfall.

CFS Rainfall Accumulation Control Data- Next 6 Weeks - October 22nd -December 6th 2021

The control member way too dry for the north of the nation and through QLD on current guidance from the climate drivers, but that persistent wet signal for the east coast is the theme on this particular product which has carried on this entire week. That is potentially 300-500mm of rainfall for eastern QLD.

GFS Rainfall Accumulation - Next 5 Weeks - October 22nd -November 24th 2021

This model has now fallen into line with the Euro and CMC showing heavier rainfall nation wide which is good to see, that means that we can now prepare for many areas to record above average rainfall and humidity values.

GFS Rainfall Anomalies - Next 5 Weeks - October 22nd - November 24th 2021

Now running wetter than last update which means that the rainfall signal is increasing across the nation.

CMC Rainfall Accumulation - Next 4 Weeks - October 22nd -November 22nd 2021

A very damp four weeks on the way, as advised in the video, your short and medium term forecasts will chop and change I am cautioning all that are making preparations for harvest to be aware of the forecast rapidly changing over the coming week, most likely trending wetter for southeast and eastern Australia. Something to watch.

CMC Rainfall Anomalies - Next 4 Weeks - October 15 - November 14 2021

Very wet look, and it is increasing each update. The west turning wetter now in the latest outlook for the medium term too. Numbers are coming up over SA and into the NT and northwest. This is picking up on the warmer waters right across northern Australia and the IOD.


TEMPERATURES

Euro Temperature Anomalies - Next 6 Weeks - October 22nd - December6th 2021

This is still closest to the post where other models are running too cool or too warm. There is likely to be below average weather for the western interior of WA and through eastern parts of Australia, especially over the coming 1-2 weeks before conditions warm further. We will feel some of that warmer and humid weather this week but then turn cooler and wetter again through November. The battle in terms of temperatures continues. The north will be the opposite, running warm for the coming 1-2 weeks before the rainfall increases. Overall this is indicative of a wet and stormy period with inconsistent temperatures throughout the continent and no especially long run of hot or cooler weather for any one area away from the southwest.

GFS Temperature Anomalies - Next 5 Weeks - October 22nd -November 24th 2021

The GFS is still running way too warm in my opinion, and while it is not impossible as nothing is impossible in weather, it is highly unlikely at this time.

More details to come on this particular product on Tuesday and a state based look on Sunday.



0 views0 comments