The impact of the typhoon to East Malaysia on orographic effect

East Malaysia has few mountains ranges which are believed to affect the cloud and rainfall distribution patterns during severe weather especially typhoon season. The study objectives are to investigate and determine the relationship between the typhoon impacts and the topography of East Malaysia. The highest mountain range in East Malaysia was the Crocker Range in Sabah, which divides the state into half. Mountain ranges in the East tend to follow north-south or northeast-southwest paths, rising to over 4095.2 meters houses by Mount Kinabalu, the highest mountain in the country, as well as Mount Trusmadi (2642m) and Mount Tambuyukon (2579m), the second and third highest peak in the country. Typhoon Ketsana was chosen for this study. The hourly rainfall products were obtained from FengYun-2D geostationary satellite. Radiosonde data from Kota Kinabalu station with Skew-T diagram and hodograph were applied in this study. A total of 5 distinct results were found in this cloud and rainfall-orography interaction during the typhoon activity. First, parts of the cloud were blocked by the Crocker Range and caused to slow down of rainfall event for a moment. Second, the heavy rainfall occurred around these mountains range. Third, the variation of cloud and rainfall distribution pattern was related to the mountain shape. Fourth, if the raining cloud was high enough and there were extra outside energy (typhoon system) the rainfall process may be forced to move forward and pass through these mountains range. Besides that, heavy rainfall distribution was more affected by the high mountains close to the shoreline than the interior region of the island. Based on this study, orography effect was important to the weather forecaster since the high mountain range was able to influence the distribution of the cloud and even rainfall patterns during typhoon season.