FILLING SEASON FOR DAMS - WILL THE RAINFALL BE ENOUGH TO BRING STORAGES WAY UP?

Well, the guidance is certainly there supporting the higher-than-average rainfall across the country, running into interior parts that are usually dry through this period, to areas of the southwest and southeast, some greater chance for higher-than-average rainfall here too.

But will it be a case of too much for the southeast and eastern inland this Winter and Spring and not enough for parts of the south and southwest?

It all comes down to cloud band orientation, the frequency of cold fronts and how these elements work together.

We can have any forecaster suggesting Armageddon, but that is not how the weather works, as using a term like that is relative and not helpful to telling you about the HOW impacts on my location from one given point to the other.

So, let’s talk about impacts on Water Storage’s now.

THIS TIME NEXT YEAR, IT IS LIKELY WE WILL BE TALKING DROUGHT! IT IS NOT A FORGONE CONCLUSION - BUT THERE WILL BE A NATURAL RESPONSE TO THIS PERIOD OF WET WEATHER.

Northern and Eastern Inland - September through December 2022

Well, it is nice to see a drier period unfold across much of QLD but, with the constant rainfall of recent months, most of the catchments across the state are at saturation point and some areas are still in residual flood which offers some concern ahead of the wetter signals coming in through the late Winter and Spring which could be in the top 5% of wet Springs for the region! It is not mucking around this year. So not only will we likely maintain 100% of dam capacity throughout the state, we will likely see residual downstream flooding ongoing following heavier rainfall events through the late Winter possibly, but probable through the Spring. So, heads up if you are living in a flood zone downstream from major dams in the state.

Southeast Inland - June through November 2022

Similar to QLD, NSW and VIC are sitting with very wet catchments, especially through the Great Dividing Range and points eastwards, which is thanks to the La Niña. Now with the rainfall we had move through during the week, this incremental rainfall, while not heavy, will just keep the subsoil wet and with the lower air temperatures and soil temperatures, coupled with a lack of sunlight, the ground will struggle to dry out, this thanks in part to the weather remaining wetter than normal through Winter. The wetter weather is forecast to be found over the southeast and southern areas of the stater for now, somewhat above average through Central and Western parts and leaning above average over Northern Areas of NSW is fair for now, but the orientation of cloud bands dictating where rainfall goes, all areas of NSW should be on alert.

Victoria should see wet weather right through the Winter and Spring. There is more capacity for heavy rainfall to unfold here, but it is a short amount of give before we see capacity reached in the major dams over the east and northeast of Melbourne. So areas downstream of major dams over West Gippsland through Maffra for example need to be watching closely. Areas downstream from Lake Dartmouth in northeast Victoria, namely places along the Mitta Mitta as an example of many in the region, need to watch the rainfall forecasts and dam levels closely. Expect flooding with the controlled releases. And areas along the Murry need to watch closely as well, I have been past Lake Hume in recent weeks and there is not much give in the system for widespread persistent heavy rainfall. So spring flooding issues and dams being at capacity is likely to feature.

Southern Inland - June through October 2022

Southern areas of the nation west of Ballarat have seen relatively below average rainfall, even with all the signals for above average rainfall, many areas through the southwest and Wimmera have seen below average rainfall, this carrying over a fair chunk of Ag SA, so these areas can deal with heavier rainfall, with water storages at about half of capacity as a whole. This will mean any heavy rainfall would be beneficial over the coming weeks and months ahead, particularly if we are talking of a drought developing at some stage in 2023. This really could be the last chance of seeing storages go the right way, with many areas relying on this disruptive season securing the following season, if things go dry through 2023. Not as concerned for flooding in this region but certainly some more give in the system is allowing for that above average rainfall signal and I am hoping it does eventuate.

Southwest Inland - June through September 2022

The region has a healthy amount of give in the system, after what was a dry Summer and temperatures being well above the average. The recent months have been more productive in terms of rainfall, we have see above average months for much of the region, a few pockets missing out but overall, been a wet Autumn. Now as we move through the traditional wet season and filling season for the SWLD, the ability to expect average rainfall is fairly high for the period, above average is marginal and dependent on the orientation of moisture and the relationships that cold fronts will have to this moisture. But following recent trends, there is a chance that most of it will stay north and east of the Ag Areas with much of this region relying on the cold fronts for widespread rainfall chances. The season looks to be active, but how active and wet, comes down to the amount of moisture coming out of the northwest. I think by the time we get to the end of September, many areas should be wetter than normal with very high sub soil moisture values through the interior but there could be some areas that walk away with and average or leaning below average season in terms of run off and filling.

Tropics In the Dry - June through September 2022

Was a little bit of a failed wet for areas away from the Daly District of the NT, with a lack of tropical depressions over the tropics leading to drier weather over inland areas south and east of Adelaide River. The rainfall finally arrived in QLD from March, but it was late, however many areas scraped to average for the wet overall. The NW of WA was patchy with some areas copping it, other areas not seeing as much. Dams and Lakes in the region doing ok, though Lake Argyle sits at about 10m below where it should be, and Darwin River Dam is now starting to fall from near capacity which is normal. The potential for early onset rainfall could lead to some early season flooding for some areas. The rainfall here could impact the ability for full dry season burns to be conducted. Use this chart below as a guide to dry season rainfall expectations which are conservative based on some climate data.

The risk of flooding for the Winter Period has been outlined here and the outlook into Spring will be refreshed soon with the risk of heavy rainfall persisting outside of the traditional filling season running fairly high entering Summer but we will know more on that in the August. But the wet signal is going to lead to the already saturated catchments becoming much wetter as we move through the months ahead.