Updated: Oct 25, 2021
We constantly talk about the impact of rainfall and temperatures on our day to day lives but there are many who need to know what the outlook is for weather relating to farm and agriculture. So I have picked out the main issues to look at over the coming 4-6 weeks. Also refer to the harvest outlooks posted yesterday. You can see previous outlooks by choosing the blog menu and clicking on climate analysis and you can feast upon the hundreds of posts there.
Fungal diseases developing during this period on crops and fruit and flower production will be moderate to high. Fruit farmers need to be aware of the higher humidity risks relating to melanose, through to brown rot and for canola farmers we have a higher risk of sclerotinia, this also impacting you bean, pea, lupin and sunflower farmers.
This will also have impact on crops ready for harvest. Severe thunderstorms are also a significant risk for NSW and QLD but will extend further south into VIC and eastern SA. We will look at this tomorrow with my forecast charts relating to the main risks.
Lets take a look at the elements.
Rainfall Outlook - Next 6 Weeks - Period Ending December 6th 2021
%chance of exceeding the median rainfall for the next 6 weeks.
The moisture and rainfall content through this period is expected to be running well above the average through the coming 6 weeks, especially as we cross into November with deeper moisture over the north being transported south and being lifted by troughs of low pressure leading to widespread showers/storms and areas of rainfall over northern and eastern Australia. Occasionally, this moisture will bring the chance of heavier rainfall into SA and western NSW and VIC. But clearly the bias of the higher rainfall opportunities exists over much of NSW, QLD and the NT. This will increase the risk of your wet weather fungal diseases for agriculture. So be prepared for disruption not only to your harvest, but impacts potentially to yields and quality of the summer crops due to the climate guidance. The higher rainfall chances will lead to soft growth, nutrient deficiencies and root disease etc.
Temperature Outlook - Next 6 Weeks - Period ending December 6th 2021.
%chance of exceeding the median temperatures for the next 6 weeks
The warmer and more humid weather over northern Australia will begin to ease, however the humidity values are heading south in the coming fortnight with increased rainfall and indeed higher dew points. There is a high risk of prolonged humid weather over eastern and northern Australia, this occasionally sitting over eastern SA and through VIC. But certainly if you are living through NSW, QLD and the NT, this period does pose a high risk of fungal disease development and could have a moderate to high impact on agriculture and harvest activities thanks to cooler and wetter weather. There is no signal for searing dry heat at this time for the nation, away from the deserts.
We have a tricky period coming up with harvest for many, some locations were hit hard over the weekend by severe weather. Severe thunderstorm outbreaks will continue to feature during the next 4-6 weeks and that is thanks to the abundance of higher humidity values and persistent upper level troughs. The blue shadings below show the persistence of lower air pressure over the nation which will lend itself to a very active forecast period. Again the current guide supports a disruptive harvest for the east and southeast and extra moisture, higher humidity and damp conditions will have impact on vulnerable agriculture.
Severe Thunderstorm Outbreaks October through April 2022.
We have already experienced 3 outbreaks over QLD and into northeast NSW and another one is due today. This will certainly be the focus of the above average severe weather season in the region and again will pose a risk to agriculture Hail has been a big feature of the storm season so far and this will continue into November and December. The risk of severe weather related to thunderstorms will graduate further south over the coming fortnight with moist, warm air clashing with colder air over the southern states. The humid air winning out so we will see a number of stormy humid days in the medium to longer term. This will also increase the duration of humidity in areas that don't usually experience that type of weather which again will lead to prolonged above average rainfall chances.
Large Hail Risk November
Relatively seasonal values for the west and north of the nation. Yes there can be marble to ping pong sized hail in the taller storms inland of Darwin, that can pose a risk to some of the produce out there but most of the mangos have been picked by now. For the east and southeast, significant hail risks remain for the remainder of this month and through November. I have already been notified of significant crop damage in Central NSW via hail storms over the weekend and this period is playing Russian Roulette with the weather for NE NSW and SE QLD. But areas further south through VIC and southern NSW must pay attention to forecasts in the coming 2-4 weeks with warmer, more humid weather developing, increasing the risk of severe weather via thunderstorms. Much of SA sits in seasonal values.
Precipitable Water Anomalies - Next 2 Weeks
The PW values are expected to be quite excessive for the next 2 weeks over northern Australia which will sit over large parts of the NT and QLD. The difference in the forecast pattern is the shift in the high pressure later this week which will be further south and east, placing Australia under a broadcast easterly flow. This will pump moisture over the eastern and southeast areas of Australia, combining with deeper moisture out of the north and northwest, there is a high chance of persistent tropical and soupy air over the east leading to that higher than average rainfall chances.
Precipitable Water Values - Green is 25mm, Yellow is 50mm - Red is 60-65mm of available precipitable water. That squeezed out via showers and thunderstorms shows you the potential rainfall and cloud production if low pressure is present. You can see the tropics are heading south early this year, so be prepared for that if you are living through QLD and NSW in particular, but even SA and VIC seeing a few humid and stormy unsettled days, with soupy air visiting. This weather is a signal of what is to come during the next 6 weeks. Remember, the higher the temperatures, the more moisture it can hold, meaning more rainfall and severe weather is possible the hotter it gets. QLD has been a great example of this. So southern areas be aware that we are running out of drier cooler days.
The SSTs across much of northern Australia is well above normal and these values are expected to increase further as we move into the Summer. The Indian Ocean Dipole is expected to peak through the coming 2-4 weeks and the ENSO region is forecast to trend into La Nina during the coming 4-6 weeks as we approach Summer. You can see the impacts of the SSTs being above average on the rainfall and humidity distribution as per above.
Humidity Impacts - Next 2 Weeks
Be aware that the tropics are usually very humid so that blue shading is not anything ground breaking. But the spread of moisture south and east from the tropics is. Note the weather that develops over Central Australia this week, for those eager arm chair weather fans. Watch how much thunderstorm activity does develop with the trough and how much rainfall falls. That will give you an indication of how much moisture will eventually shift south and east into the medium term when the gate opens up, the pattern allows for low pressure to dominate and increase rainfall chances for the eastern two thirds of the nation. The southwest stays under seasonal weather but cooler weather, thanks to the persistent upper ridge in the region. There appears to be no frontal weather to push out the humidity at this time, however IF a low pressure system develops, this may push moisture north away from the southeast. So a few elements to watch, the takeaway, it is going to be getting much more humid as we go through the next 2-4 weeks.
Soil Moisture Forecast - Early November
This is suggesting that inland areas under constant showers and thunderstorms, will see increasing soil moisture. The southeast has dried out a little with the last of the flood warnings over for now, but with increasing rainfall chances redeveloping and thunderstorms returning in these areas, there is the chance of flooding coming back during November for southeast areas of NSW and northeast VIC in particular. Soil moisture will increase over the northern and eastern parts of the nation. Conditions have also improved through QLD after recent storm outbreaks and this looks to be maintained during the period. Conditions not saturated through QLD but pockets of NSW and VIC are quite wet ahead of the next burst of humidity and thunderstorm activity. Conditions through SA are relatively seasonal at the moment, so areas a bit dry but not uncommon being closer to the Goyder's Line.
Soil Temperature Forecast - November 9th 2021.
Soil temperatures have been below average for much of Spring through parts of southern and southwest Australia with more rainfall than normal and cooler atmospheric temperatures. This will start to shift in the coming 2-4 weeks as we get a nice pulse of warmer air coming down from the tropics from this week and then a more prolonged period of warmer weather through early November thanks to the absence of cold fronts and westerly winds. However the cloud cover from inland troughs may lead to cooler weather, the overall trend will be warming soil temperatures regardless as we move to summer and longer days.
Temperature Anomalies - Next 2 Weeks
The high amplitude pattern will lead to large fluctuations in temperatures with most of the nation experiencing the warmer than normal weather contrasting with the cooler to colder than normal weather. The southwest and southeast of the nation to be experiencing this. However, this parameter also highlights, with moisture and unsettled weather getting involved, the volatile weather is expected for at least the coming 2 weeks and beyond.
Temperature Anomalies - November 1-8 2021
Mixed temperature odds across the country with a high amplitude pattern and high moisture content. This is going to lead to inland rain and storms moving from west to east with warmer weather ahead of these features but some areas of the east and north could sit under thick cloud and rainfall during this period. The far northern tropics and pockets of southern Australia could see above average temperatures and the southwest cooler than normal under persistent ridging.
I will have another look at the Farm Focus coming up tomorrow looking at disease risks and weather.