It was not quite the Namoi flood of old but nevertheless a welcome relief for a river desperate for a good flush out.
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Gunnedah’s river height peaked at 7.18 metres at 11pm Friday, well below the 7.3m minor flood level.
Downstream at Boggabri, where a 7m minor flood level was forecast, the Namoi peaked at 6.85m by 5pm Sunday.
The rising levels followed a wet week for Boggabri which recorded 44 millimetres of rain in 24 hours to 9am on Wednesday – one of the highest totals anywhere in the north west.
Gunnedah was not far behind with 39 points after another heavy drenching late Sunday. They scored 5.6mm in just three hours to 6pm.
For three days crowds were drawn to the Gunnedah riverbank near Cohen’s Bridge. Parents snapped pictures on phones and described to kids where the water line used to be.
After years of creek cracking drought, the allure of a flood, however small, was too good an opportunity to pass up.
One woman pointed to the half-submerged concrete pillars which usually dot the edge of the riverside carpark. She was able to park her car there Thursday afternoon but by mid-morning Friday, it was boat-only access.
So what’s causing all the rain, flooded rivers and spate of grey skies in NSW’s north west? Believe or not, the answer lies more than 5000km away in the Indian Ocean.
Specifically, a climate driver called the negative Indian Ocean Dipole (IOD).
A negative IOD means that as warm ocean temperature track toward Australia’s west coast, rain clouds follow. It’s these clouds which have produced much of the late winter, early spring rainfall in our eastern states.
Senior Climatologist at the Bureau of Meteorology, Agata Imielska, said this year’s IOD negative value for July was one of the strongest they had seen.
Also influencing weather models is a 50 per cent chance of a La Nina event occurring in the Pacific Ocean. Australia’s northern and eastern states can usually expect above average Spring rain during a La Nina event.
Gunnedah’s Wednesday’s forecast will see a high chance of rain returning to the plains and chance of a thunderstorm in the morning. Winds will be between 15-25km/h and temperatures between 8-21 degrees.
A moderate flood warning was in place for the Namoi at Wee Waa late Monday evening.
