Abstract
Rollover accident of fishing boats occurred in Tsushima, Nagasaki Prefecture between 3 and 4 am on Sep 1th, 2015 due to a strong wind gust attack. Actually, if the strong wind gust including a tornado occurs at night, we cannot visually and clearly recognize a dangerous situation such as the approach of the tornado. Moreover, it is extremely difficult to predict the occurrence of the wind gust. Therefore, it is very important to provide a useful tool for recognizing a wind gust event such as tornado attack.
This study investigated rainfall intensity features related to the wind gust events (54 events) caused by frontal activities in Western and Eestern Japan between 2007 and 2013, on the basis of weather radar analysis. From these results, it was found that aproximantely 80% of the total wind gust events accompanies the distribution of strong radar-based rainfall intensity more than 80mm/h at the timing of a wind gust occurrence within the designated narrow area (the width of 0.2 degree in longitude and latitude) determined in ahead. This implies that the distribution of strong rainfall intensity appear near a dominat wind gust region. Moreover, when the area for the detection of the strong radar intensity was expanded into the width of 1.0 degree in longitude and latitude, it was also found that approximately 70% of the total wind gusts events was detectable in the wide region within an hour before the occurrence of these wind gusts.
These results show that the detection of strong radar intensity distribution using a weather radar is effective for decision-making of the evacuation from a wind gust including a tornado related to frontal activities within an hour before the occurrence of these wind gusts.
