In January 2010 there were two tropical cyclones in the Coral Sea at the same time.
Neville, close to our coast, and Olga rapidly approaching Neville from the East. Two systems perfectly suited to begin the phenomenon known as the Fujiwara effect.
Dr Sakuhei Fujiwhara was a Japanese meteorologist in 1921 who, for reasons known only to himself, was farnarkling around with laboratory experiments on vortexes and whirlpools in water.
Maybe a childhood fascination with water disappearing down plug holes had opened his door to this scientific pathway.
Be that as it may or may not, he discovered unexpected interactions occurring when one vortex came under the influence of another, and it led him to postulate that similar effects would occur in the Earth's atmosphere, which behaves in a similar manner to the liquids he was experimenting with.
Only after weather satellites were launched in the 1960's could scientific proof be obtained, and observations made, to confirm his theories.
When two similar strength cyclones approach each other they will tend to cylindrically rotate around each other about a central pivot point determined by the relative strength of each system.
It is a relatively uncommon occurrence. Perhaps twice a year in the Pacific ocean, and once every three years in the Atlantic.
(The difference explained simply because there are more cyclones each year in the Pacific.)
The two cyclones will rotate like a slowly turning horizontal dumbbell in a movement known as a Fujiwara dance or waltz.
The Fujiwara effect typically involves four stages.
1. Approach and capture; the orbits of the 2 storms begin to interact.
2. Mutual orbit; begin Fujiwara dance.
3. Merger; one storm if more intense will trap the smaller storm.
4. Escape; one storm may depart from the Fujiwara effect, or
upper level atmospheric influences may cause the storms to
split and resume independent courses.
Neville and Olga demonstrated this final scenario, making monkeys out of the forecasters attempting to predict tracks for the two systems. Neville was fractured and flung more than 100km South, while Olga weakened into a rain depression on a westward track bringing drenching rain to us as well as a huge area of arid Northern and Central Australia.
Our rain gauge measured 548mm (22") in 4 days.
Isn't weather, nature and science absolutely fascinating and full of wonder?
Please forgive this burst of unrestrained meteorological enthusiasm.
P.S "Farnarkle" is a little known Australian word meaning to "mess around with",
or more accurately "fart around with" something.