18 Aug 2015

Taiwan under threat from second typhoon in a fortnight

Just ten days ago, Taiwan was hit by Typhoon Soudelor, which left six people dead and a trail of destruction across the island nation.

Whilst there were damaging gusts of wind, the main hazard was the huge amount of rain that fell, triggering flooding and landslides.

As the country repairs the damage from Typhoon Soudelor, another powerful storm, Typhoon Goni, is spinning around in the western Pacific Ocean.


Even though there is still time for the forecast to change, many of the weather computer models predict that the storm will get perilously close to Taiwan later this weekend.

Typhoon Goni’s uncertain path

Powerful storms like typhoons thrive on the warm, tropical ocean waters, which provide them with a source of energy on which they flourish.

This year, an El Nino has meant that ocean temperatures have been well above normal in the western Pacific Ocean, with lots more energy to fuel storms.

As a result, the ongoing existence of Typhoon Goni is certain. What is uncertain is what path it will take and precisely how powerful it will be.


The latest prediction from the Joint Typhoon Warning Center predicts that Typhoon Goni will get very close to north east Taiwan on Sunday, local time.

However, this prediction is an agglomeration of information provided by a number of computer models, which has then been interpreted by a human forecaster to produce a best guess.

Ensembles and multiple predictions

Interestingly, the graphic below shows the predicted path from an ensemble run.

ensemble_Goni_TT_wpEffectively, an ensemble is when the same model is run lots of times, but with a slightly different set of starting conditions each time, to give a most likely path from a spread of possible outcomes.

The black line is the main prediction, but you can see the orange and red lines clustered around them, each representing another prediction.

You’ll notice that all the lines are close together for the next 96 hours (labelled in black text), but thereafter, the lines start to diverge.

This is because the further ahead in time that you go, the more uncertain the track and intensity of the typhoon becomes.

If you look closely, you can see that some of the predictions take it very close to eastern Taiwan, but most of them, for now at least, keep the storm offshore.

Nevertheless, there is still plenty of time for the forecast to change, and it doesn’t take much of change to put Taiwan back in the path of more potentially deadly weather.

I’ll be keeping an eye on the progress of this storm in the coming days and posting updates on Twitter – @liamdutton

Images: NOAA, Nasa, Tropicaltidbits.com

Tweets by @liamdutton