Mysterious weather model may help predict cyclone 20 days in advance

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Melbourne, Sep 1 (ANI): Weather forecasters may now use a mysterious weather pattern, called the Madden Julian Oscillation, to predict cyclones up to three weeks ahead of time.

Forecasters have previously used the above phenomenon to predict how active each cyclone season might be, and to forecast their behaviour about five days into the future once they form.

However, the forecasts had a big gap of uncertainty.

But Dr. Frederic Vitart, of the European Centre for Medium-Range Weather Forecasts, is now trying to bridge that gap, and has thus shed light on the way the oscillation influences tropical storm formation, intensity and movement.

The oscillation alternates between a vast province of moist, stormy air and an unusually dry patch. Then it slowly blows through the tropics, often circling the globe several times.

Vitart used a computer simulation of the last 20 years of cyclone seasons, to show that it could increase or decrease the risk that a storm would make landfall by as much as 50 percent.

"The Madden Julian Oscillation creates large-scale conditions which are known to favour tropical storm genesis," he said.

He also said that the phenomenon brings with it increased moisture and weakening wind shear.

The model reliably predicts storm formation out to about 20 days.

As the oscillation is a diffuse, widespread weather pattern, using it to forecast cyclones can dramatically improve forecasts, but it does not turn weather models into crystal balls.

He said that despite knowing the oscillation's influence on Hurricane Katrina, no one could have foreseen the storm's devastating strike on New Orleans.

"We may not be able to predict the strike of a storm at a given time and given location, but we can predict if the probability of a tropical storm strike will increase or decrease in the next few weeks over a large area," ABC Science quoted Vitart as saying.

Dr Gabriel Vecchi of the National Oceanic and Atmospheric Administration, said: "The Madden Julian Oscillation would help us to predict the genesis of a storm that doesn't exist yet, and the likely character of its track, landfall, etc."

Vitart said that he is working on developing a way to use this type of forecasting to construct maps that display advanced warning of increased cyclone risk for a given stretch of islands or coastline.

The results have been published in the journal Geophysical Research Letters. (ANI)

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