Establishment of windstorm-producing thunderstorms hazard threshold in peninsular Malaysia

Abstract

Establishment of guideline to distinguish between low risk and high-risk windstorm occurrences is important in windstorm disaster management, especially, for purpose in disseminating early warning to the public and local authorities. Hazard threshold as supporting tool in windstorm early warning system, so that, monitoring of these phenomena only to be focused on high-risk windstorm occurrences. High-risk windstorm occurrences are occurrences with a higher intensity than hazard threshold whereby if this particular windstorm did occur, it could cause significant damages. Significant damages are damages that causing loss property, injury and claim life to the human. In order to establish this supporting tool, 56 windstorm occurrences from 6 regions in Peninsular Malaysia were selected as study cases. Estimation of intensity for each significant damage also taken into account the effect of local conditions. Besides, the damages and meteorological station should be underneath the same convective cluster and in-position with wind direction that had intensity. Through this study, it was found that the hazard threshold in Peninsular Malaysia is 9.0 m/sec (32.4 km/h) of gust speed at 1 min duration.