Digital Typhoon: Summary of Typhoons in 2004

We updated the AMeDAS Statistics for 2004 data, so this is a good chance to reanalyze typhoons that approached Japan during 2004 by searching Typhoon Disaster Information Database. Here we compare heavy rains and strong winds of 2004 typhoons with past typhoons using Typhoon Impact Index. Precipitation Impact Index Typhoons in 2004 with an especially large precipitation impact index is Typhoon 200423, and it ranks third in history following Typhoon 197617 and Typhoon 199019. The most interesting point is the large precipitation impact index in spite of the relatively moderate total precipitation amount of 500mm observed at top-ranking stations during Typhoon 200423. The reason is that rainfall became large evenly across Japan, so the sum of precipitation amount of many points resulted in a large number; hence it is a symbolic number that represents the extent of disasters across Japan. Typhoon 200421 appears next, but the order is just as low as 22th. Of course it is because the heavy rain of this typhoon was localized and it does not mean that the amount of rain was small. But we can conclude that the year 2004 was not the year of many large rainy typhoons. Wind Impact Index In contrast to the precipitation impact index, the wind impact index has three typhoons within top 10 typhoons, such as Typhoon 200418 (1st), Typhoon 200416 (3rd), and Typhoon 200423 (8th). Comparing the impact of heavy rains and strong winds, we can say that "the year 2004 was the year of windy typhoons." The largest damage in 2004 was recorded by Typhoon 200418, and the primary reason of the largest damage lies in the strong winds of this typhoon which was one of the strongest in these 30 years. The disasters of storm surge, which is another frequent type of disasters in 2004, was also caused by the successive approach of such powerful windy typhoons. In short, in a historical context, the year 2004 can be characterized as the year of especially strong winds. Composite Impact Index As many as three typhoons ranked within top 5 typhoons in history, namely Typhoon 200423 (2nd), Typhoon 200418 (4th), Typhoon 200416 (5th). This ranking of the composite impact index illustrates that the year 2004 was the year of unprecedentedly frequent strike of powerful typhoons against Japan. If we classify the higher ranking typhoons, Typhoon 200423 is an almighty-type typhoon with large indices of both heavy rains and strong winds, while Typhoon 200418 and Typhoon 200416 are windy-type typhoons with a larger wind impact index.

The number of typhoons in the year 2004 was 29, a little larger than the average number of 27. For Japanese people, however, this year may be remembered as "the year of disasters" because of the unprecedented number of typhoon strikes against Japan and subsequent disasters. The positive result of this phenomenon is that people can now understand the fact that every typhoon has its own unique character because they could compare many typhoons while keeping their clear memory about what happened, and that the analysis of typhoon characters in advance may be effective for disaster mitigation and prevention. The following statistics partially came from Japan Meteorological Agency.

Typhoons that made landfall on Japan (Ave 2.6) : 10 (record / previous record 6)
Typhoons that passed near Nansei Islands (Okinawa) (Ave 7.2) : 15 (record / previous record 12)
Typhoons that passed near Japan (Ave 10.8) : 19 (one of the largest tied with 1960 and 1966)
Typhoons that reached the 30N line around Japan (120E-150E) keeping the "strong typhoon" category : 10 (Past)

The reason of so many typhoons drawing near Japan is assumed that the edge of the high pressure system in the Pacific Ocean, which coincides with the path of typhoons, has been staying around Japan this year. But when you further ask the reason of that, there are still many issues that do not have clear answers. In addition, typhoon disasters this year are not restricted to Japan, and such countries as Philippines, China and Taiwan suffered from severe typhoon disasters. In the following, significant typhoons of this year are reviewed (the number of deaths is according to Fire and Disaster Management Agency). Typhoon 200416 (CHABA) This is the strongest typhoon of this year, and after traversing Kyushu, it moved across Japan Sea. Because the track of the typhoon, its strong intensity, and the highest season of the tide, it caused favorable conditions for the storm surge and tidal wave, resulting in huge damage in Kagawa, Okayama and Hiroshima prefectures along Setonaikai Sea. Tidal waves in those areas were almost correctly forecasted in advance, but evacuation measures were taken far later than reality, and this disaster lead to the fundamental revision of disaster management processes in those areas. Typhoon 200418 (SONGDA) This typhoon moved on a similar track with Typhoon 200416 (CHABA) mentioned above, and it kept its intensity after making landfall on Kyushu to move across Japan Sea. Because it regained its intensity when it drew near to Hokkaido to produce unusually strong winds, resulting in extensive damage ranging from agriculture to forestry and infrastructure whose scale is like once in tens of years, The total amount of claims for property and casualty insurance companies reached 267.3 billion yen, which overwhelmed any other weather disasters occurred this year in Japan. Typhoon 200421 (MEARI) This typhoon made a sharp turn around Okinawa, and came back to Japan as if it was targeting Japan from the start. Its intensity in terms of central pressure was not so strong, but heavy rains in Kii peninsula and Mie prefecture, areas of the frequent occurrence of heavy rains, were far more than expected, and those areas had the simultaneous occurrence of landslides and flooding. Ehime prefecture also suffered from many landslides that lead to large disasters. Typhoon 200422 (MA-ON) Typhoon rush was not over. This typhoon was a small typhoon in the beginning, but it intensified rather unexpectedly in south of Japan and it rushed into Izu Peninsula without losing its intensity. Izu Peninsula suffered from wind disasters like those of tornadoes, but Tokyo, being under its highest alert, had only minor impact because of its rapid weakening after making landfall. Typhoon 200423 (TOKAGE) People were already tired of typhoons, but in spite of their hope this typhoon came to Japan again. Figures such as central pressure was not eye-catching compared to other typhoons of this year, but its very large area of strong winds was outstanding from the beginning. It then reached Japan without losing its intensity, and areas such as the coast of Japan Sea and Setonaikai Sea, known as relatively rare occurrence of typhoon disasters, started to suffer from heavy rains and strong winds. After the next day we realized that the damage was so extensive over Japan that we had as many as 94 deaths (3 missing) which is the largest in these 25 years of typhoon disasters. The mass media quickly turned their attention to the disasters of the Mid Niigata prefecture Earthquake which occurred soon after that of Typhoon TOKAGE. This typhoon, however, can be said as the "most problematic" typhoon of this year, suggesting many problems in terms of disaster prevention and mitigation.

Philippines The number of casualties exceeded 1500 due to the subsequent attacks of three typhoons, Typhoon 200425 (MUIFA), Typhoon 200426 (MERBOK), Typhoon 200427 (NANMADOL) and another tropical storm Winnie (Philippine name). China Zhejian Province suffered from the largest damage in these several years by Typhoon 200413 (RANANIM). Taiwan Large-scale damage includes that in southern and mountainous areas by Typhoon 200407 (MINDULLE), and that in northern and mountainous areas by Typhoon 200417 (AERE). Countries and regions in the Pacific Large-scale damage includes that in Yap Island by Typhoon 200401 (SUDAL), and that in Saipan Rota Island by TYphoon 200416 (CHABA).

This year people often referred to the record-breaking number of landfall typhoons on Japan in the context of abnormal weather. It seems that there are growing interests about a possible connection between unusual weather and so-called "global warming." To be honest, that relationship may exist, but we haven't seen the evidence. This year's phenomena should be thoroughly examined from the scientific point of view, but it is also true that atmospheric conditions in a global scale happened to fall into a state in which Japan had many typhoons in a local scale. Hence it may be a leap of logic to say that "the climate of the earth is abnormal because Japan had many typhoon landfalls this year." More meaningful question is how the long-term trend of the characteristics and tracks of typhoons changes in relation to climate change such as global warming. A noteworthy fact is that we had many typhoons that reached the 30N line around Japan (120E-150E) keeping the "strong typhoon" category. Does this suggest that northern areas such as Japan are likely to have more strong typhoons in the future? If this is true, we need to rethink current measures against typhoons. It is generally agreed that the trend is still not observed (or to put it more correctly, we still cannot say that the trend is observed). We however have to pay attention to the activity of typhoons after 2005 to check whether the trend can be observed or not. In the world, the repeated strikes of hurricanes in 2004 also raised people's attention to severe weather. Hurricane Charley, Frances, Ivan, Jeanne have left severe damage over the United States and Caribbean countries, and Hurricane Jeanne was the most catastrophic that killed more than 2000 people in Haiti. It has been pointed out that we may have more severe weather in the future if the warming of the earth continues. Year 2004 was the year that this warning was taken seriously with our real experience.

Digital Typhoon: Summary of Typhoons in 2004

Summary of Information on Typhoons in 2004

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