Weather

Humid air and lingering troughs lead to rain with no end in sight

Written by Jane Bunn - Jane's Weather | Nov 29, 2024 1:55:33 AM

Rain continues across a large part of the country impacting harvest planning and creating problems with high humidity.

We’re in a very stagnant weather pattern.

Tropical moisture from the much warmer than average waters off northern and eastern Australia is funnelled across eastern Australia thanks to a broad high to our south. 

The shape of this high is important - see how it’s like a jelly bean, cradling the low pressure troughs over the east.

This means the troughs are stuck there, lingering day after day, turning that tropical moisture into widespread rain.

BoM’s weather pattern on Friday morning

The potential rainfall for the next week builds on already significant falls over much of central and eastern Australia in the past week - there is still a lot more to come.

Widespread 25 to 100 mm across the NT, QLD, NSW, VIC, TAS and SA (with the potential for even heavier falls directly under a storm) - missing southwest WA which is in a very different weather pattern. 

Potential rain from Friday 29th November to Friday 6th December

Over southern Australia, a lot of this rain would have been much more helpful earlier in winter and spring. Instead we are reaching peak rain activity as we go into harvest. 

The pattern means the high humidity that’s usually confined to northern Australia has worked its way right through to Tasmania, and that’s having an impact on grape growers and other industries. 

And it is here to stay - see this example for Melbourne. The high humidity lingers through the weekend and into early next week, as the rain systems keep moving through. There is a break mid week, but it doesn’t last for long, with the humidity coming back even stronger at the end of the week:

The latest outlook for summer from BoM builds on earlier forecasts of increased chances for wetter than average weather. The chances are even higher now in the eastern states, and the area of drier than average over the centre has disappeared. 

Modelling suggests that most of this rain is likely in December with rain easing as we go into next year - and with the sources of moisture plus the stagnant weather pattern, we can be assured that at least the first part of December will be rain filled for central and eastern Australia. 

BoM’s forecast for summer rain potential: Green areas show an increased chance of exceeding the median (or average) rain for this time of year

Check the full details at Jane’s Weather to keep up to date on what the models are projecting for your spot. If you’d like an in depth analysis don’t miss my weekly video update - perfect if you have 15 minutes to spare! 

 

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