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September 2017

Summer 2017: Reform in “Information for Severe Weather Preparation” and Torrential Rain Disasters

How News Reporting Has Changed

Hidehiko Fukunaga

The Japan Meteorological Agency drastically reformed its “Information for Severe Weather Preparation” system during the period from May to July 2017. The reform focused on how to convey the imminence of a disaster from an early stage in a visualized, easy-to-understand manner. This article sheds light on how the new system actually visualized the imminent disaster risks of the torrential rain that hit Shimane Prefecture and northern Kyushu on July 5, 2017 and how NHK reported the information, in order to examine the changes in media reports on flood. The results of the survey and analyses include the following.

- Among the newly introduced disaster information, the level of “probability of warnings” (“high” or “mid”) and color coding of expected warnings or advisories by time slot were able to alert the likelihood of heavy rain to some degree. However, they were not able to warn the possibility of extraordinary heavy rains from the early stage of the forecast. It was due to the nature of cumulonimbus clouds that develop quickly and locally, which makes it difficult to forecast.

- Heavy rain warning and flood warning are complemented by “real-time inundation risk map” and “real-time flood risk map.” Each map accurately visualized the imminent disaster by displaying the highest level of risk.

- More than 90 minutes before the rain emergency warning was issued in municipalities in Fukuoka Prefecture, NHK reported the fact that the risk maps showed the highest levels. Reporters explained to viewers in real time how to interpret the risk maps. It is expected that real-time commentaries will become more sophisticated with technological advancement of high speed processing and visualization of big data.

- The real-time flood risk map changed the flood reporting style, from focusing on the main stream to covering the entire basin including small and medium-sized rivers. This enables reporters to refer to specific names of rivers facing high flood risk and offer bird’s eye commentaries on the area including how the main stream and its tributaries are correlated.

The NHK Monthly Report on Broadcast Research


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