Explaining the different “Ruby” forecasts
CHEERS TO GMA News Online for explaining what was in everybody’s minds as Typhoon Ruby (Hagupit) was approaching the Philippines: Why did the forecasts of Ruby’s path not agree?
Last Dec. 4, after Ruby had crossed into the Philippine Area of Responsibility (PAR), its path was predicted by the Philippine Atmospheric, Geophysical and Astronomical Services Administration (PAGASA) and various international weather agencies. Curiously, the forecasts were different from each other. For example, depending on which agency was saying it, the storm was supposed to have made its first landfall in Eastern Samar, and in northern and central Luzon, Eastern Visayas and the CARAGA region. (News reports later quoted PAGASA officials as saying that Ruby made its first landfall in Dolores, Eastern Samar).
In its Dec. 4 piece aptly titled “Ano nga ba talaga? Why forecasts for Ruby differ?”, GMA News Online explained the differences in the forecasts. “The best that anyone can do is to provide an educated guess of the future based on current and previous information. Each agency relies on different measuring systems and formulas to make a careful assumption of how strong a typhoon will be and where it is likely to go,” it said. “For example, aside from computer models, PAGASA also considers the tracks of previous typhoons during this time of the year.”
The report quoted HurricaneScience.org which stated: “The accuracy of hurricane forecast models can vary significantly from storm to storm. For some storms, the factors affecting the hurricane track are relatively straightforward, and the models are not only accurate but they produce similar forecasts, while for other storms, the factors affecting the hurricane track and more complex, and different models produce very different forecasts.”
GMA News Online added that regardless where Ruby’s landfall was, it had a diameter of around 600 kilometers so the storm would have definitely affected areas far from its landfall point.
Thanks for the kudos! 😀